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Filesystem Hierarchy Standard
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<HEAD
><script>function PrivoxyWindowOpen(){return(null);}</script><TITLE
>Filesystem Hierarchy Standard</TITLE
><META
NAME="GENERATOR"
CONTENT="Modular DocBook HTML Stylesheet Version 1.7"></HEAD
><BODY
CLASS="BOOK"
><DIV
CLASS="BOOK"
><A
NAME="AEN1"
></A
><DIV
CLASS="TITLEPAGE"
><H1
CLASS="TITLE"
><A
NAME="AEN2"
>Filesystem Hierarchy Standard</A
></H1
><H3
CLASS="CORPAUTHOR"
>Filesystem Hierarchy Standard Group</H3
><H4
CLASS="EDITEDBY"
>Edited by</H4
><H3
CLASS="EDITOR"
>Rusty Russell</H3
><H3
CLASS="EDITOR"
>Daniel Quinlan</H3
><H3
CLASS="EDITOR"
>Christopher Yeoh</H3
><P
CLASS="COPYRIGHT"
>Copyright &copy; 1994-2004 Daniel Quinlan</P
><P
CLASS="COPYRIGHT"
>Copyright &copy; 2001-2004 Paul 'Rusty' Russell</P
><P
CLASS="COPYRIGHT"
>Copyright &copy; 2003-2004 Christopher Yeoh</P
><DIV
><DIV
CLASS="ABSTRACT"
><P
></P
><A
NAME="AEN30"
></A
><P
>This standard consists of a set of requirements and guidelines for file
and directory placement under UNIX-like operating systems.  The
guidelines are intended to support interoperability of applications,
system administration tools, development tools, and scripts as well as
greater uniformity of documentation for these systems.</P
><P
></P
></DIV
></DIV
><DIV
CLASS="LEGALNOTICE"
><P
></P
><A
NAME="AEN25"
></A
><P
>All trademarks and copyrights are owned by their owners, unless
specifically noted otherwise.  Use of a term in this document should not
be regarded as affecting the validity of any trademark or service
mark.</P
><P
>Permission is granted to make and distribute verbatim copies of
this standard provided the copyright and this permission notice are
preserved on all copies.</P
><P
>Permission is granted to copy and distribute modified versions of this
standard under the conditions for verbatim copying, provided also that
the title page is labeled as modified including a reference to the
original standard, provided that information on retrieving the original
standard is included, and provided that the entire resulting derived
work is distributed under the terms of a permission notice identical to
this one.</P
><P
>Permission is granted to copy and distribute translations of this
standard into another language, under the above conditions for modified
versions, except that this permission notice may be stated in a
translation approved by the copyright holder.</P
></DIV
><HR></DIV
><P <A HREF=http://www.pathname.com/fhs/ >Here</A> is the home of the Filesystem Hierarchy Standard (FHS). The copy you are reading is version 2.3. It was announced on January 29, 2004. </P
></P
></DIV
><HR></DIV
><DIV
CLASS="TOC"
><DL
><DT
><B
>Table of Contents</B
></DT
><DT
>1. <A
HREF="#INTRODUCTION"
>Introduction</A
></DT
><DD
><DL
><DT
><A
HREF="#PURPOSE"
>Purpose</A
></DT
><DT
><A
HREF="#CONVENTIONS"
>Conventions</A
></DT
></DL
></DD
><DT
>2. <A
HREF="#THEFILESYSTEM"
>The Filesystem</A
></DT
><DT
>3. <A
HREF="#THEROOTFILESYSTEM"
>The Root Filesystem</A
></DT
><DD
><DL
><DT
><A
HREF="#PURPOSE2"
>Purpose</A
></DT
><DT
><A
HREF="#REQUIREMENTS"
>Requirements</A
></DT
><DT
><A
HREF="#SPECIFICOPTIONS"
>Specific Options</A
></DT
><DT
><A
HREF="#BINESSENTIALUSERCOMMANDBINARIES"
>/bin : Essential user command binaries (for use by all users)</A
></DT
><DD
><DL
><DT
><A
HREF="#PURPOSE3"
>Purpose</A
></DT
><DT
><A
HREF="#REQUIREMENTS2"
>Requirements</A
></DT
><DT
><A
HREF="#SPECIFICOPTIONS2"
>Specific Options</A
></DT
></DL
></DD
><DT
><A
HREF="#BOOTSTATICFILESOFTHEBOOTLOADER"
>/boot : Static files of the boot loader</A
></DT
><DD
><DL
><DT
><A
HREF="#PURPOSE4"
>Purpose</A
></DT
><DT
><A
HREF="#SPECIFICOPTIONS3"
>Specific Options</A
></DT
></DL
></DD
><DT
><A
HREF="#DEVDEVICEFILES"
>/dev : Device files</A
></DT
><DD
><DL
><DT
><A
HREF="#PURPOSE5"
>Purpose</A
></DT
><DT
><A
HREF="#SPECIFICOPTIONS4"
>Specific Options</A
></DT
></DL
></DD
><DT
><A
HREF="#ETCHOSTSPECIFICSYSTEMCONFIGURATION"
>/etc : Host-specific system configuration</A
></DT
><DD
><DL
><DT
><A
HREF="#PURPOSE6"
>Purpose</A
></DT
><DT
><A
HREF="#REQUIREMENTS3"
>Requirements</A
></DT
><DT
><A
HREF="#SPECIFICOPTIONS5"
>Specific Options</A
></DT
><DT
><A
HREF="#ETCOPTCONFIGURATIONFILESFOROPT"
>/etc/opt : Configuration files for /opt</A
></DT
><DT
><A
HREF="#ETCX11CONFIGURATIONFORTHEXWINDOWS"
>/etc/X11 : Configuration for the X Window System (optional)</A
></DT
><DT
><A
HREF="#ETCSGMLCONFIGURATIONFILESFORSGMLAN"
>/etc/sgml : Configuration files for SGML (optional)</A
></DT
><DT
><A
HREF="#AEN795"
>/etc/xml : Configuration files for XML (optional)</A
></DT
></DL
></DD
><DT
><A
HREF="#HOMEUSERHOMEDIRECTORIES"
>/home : User home directories (optional)</A
></DT
><DD
><DL
><DT
><A
HREF="#PURPOSE10"
>Purpose</A
></DT
><DT
><A
HREF="#REQUIREMENTS4A"
>Requirements</A
></DT
></DL
></DD
><DT
><A
HREF="#LIBESSENTIALSHAREDLIBRARIESANDKERN"
>/lib : Essential shared libraries and kernel modules</A
></DT
><DD
><DL
><DT
><A
HREF="#PURPOSE11"
>Purpose</A
></DT
><DT
><A
HREF="#REQUIREMENTS5"
>Requirements</A
></DT
><DT
><A
HREF="#SPECIFICOPTIONS7"
>Specific Options</A
></DT
></DL
></DD
><DT
><A
HREF="#LIBLTQUALGTALTERNATEFORMATESSENTIAL"
>/lib&lt;qual&gt; : Alternate format essential shared libraries (optional)</A
></DT
><DD
><DL
><DT
><A
HREF="#PURPOSE12"
>Purpose</A
></DT
><DT
><A
HREF="#REQUIREMENTS6"
>Requirements</A
></DT
></DL
></DD
><DT
><A
HREF="#MEDIAMOUNTPOINT"
>/media : Mount point for removeable media</A
></DT
><DD
><DL
><DT
><A
HREF="#PURPOSEMEDIAMOUNTPOINT"
>Purpose</A
></DT
><DT
><A
HREF="#SPECIFICOPTIONSMEDIAMOUNT"
>Specific Options</A
></DT
></DL
></DD
><DT
><A
HREF="#MNTMOUNTPOINTFORATEMPORARILYMOUNT"
>/mnt : Mount point for a temporarily mounted filesystem</A
></DT
><DD
><DL
><DT
><A
HREF="#PURPOSE13"
>Purpose</A
></DT
></DL
></DD
><DT
><A
HREF="#OPTADDONAPPLICATIONSOFTWAREPACKAGES"
>/opt : Add-on application software packages</A
></DT
><DD
><DL
><DT
><A
HREF="#PURPOSE14"
>Purpose</A
></DT
><DT
><A
HREF="#REQUIREMENTS7"
>Requirements</A
></DT
></DL
></DD
><DT
><A
HREF="#ROOTHOMEDIRECTORYFORTHEROOTUSER"
>/root : Home directory for the root user (optional)</A
></DT
><DD
><DL
><DT
><A
HREF="#PURPOSE15"
>Purpose</A
></DT
></DL
></DD
><DT
><A
HREF="#SBINSYSTEMBINARIES"
>/sbin : System binaries</A
></DT
><DD
><DL
><DT
><A
HREF="#PURPOSE16"
>Purpose</A
></DT
><DT
><A
HREF="#REQUIREMENTS8"
>Requirements</A
></DT
><DT
><A
HREF="#SPECIFICOPTIONS8"
>Specific Options</A
></DT
></DL
></DD
><DT
><A
HREF="#SRVDATAFORSERVICESPROVIDEDBYSYSTEM"
>/srv : Data for services provided by this system</A
></DT
><DD
><DL
><DT
><A
HREF="#PURPOSE16A"
>Purpose</A
></DT
></DL
></DD
><DT
><A
HREF="#TMPTEMPORARYFILES"
>/tmp : Temporary files</A
></DT
><DD
><DL
><DT
><A
HREF="#PURPOSE17"
>Purpose</A
></DT
></DL
></DD
></DL
></DD
><DT
>4. <A
HREF="#THEUSRHIERARCHY"
>The /usr Hierarchy</A
></DT
><DD
><DL
><DT
><A
HREF="#PURPOSE18"
>Purpose</A
></DT
><DT
><A
HREF="#REQUIREMENTS9"
>Requirements</A
></DT
><DT
><A
HREF="#SPECIFICOPTIONS9"
>Specific Options</A
></DT
><DT
><A
HREF="#USRX11R6XWINDOWSYSTEMVERSION11REL"
>/usr/X11R6 : X Window System, Version 11 Release 6 (optional)</A
></DT
><DD
><DL
><DT
><A
HREF="#PURPOSE19"
>Purpose</A
></DT
><DT
><A
HREF="#SPECIFICOPTIONS10"
>Specific Options</A
></DT
></DL
></DD
><DT
><A
HREF="#USRBINMOSTUSERCOMMANDS"
>/usr/bin : Most user commands</A
></DT
><DD
><DL
><DT
><A
HREF="#PURPOSE20"
>Purpose</A
></DT
><DT
><A
HREF="#SPECIFICOPTIONS11"
>Specific Options</A
></DT
></DL
></DD
><DT
><A
HREF="#USRINCLUDEDIRECTORYFORSTANDARDINCLU"
>/usr/include : Directory for standard include files.</A
></DT
><DD
><DL
><DT
><A
HREF="#PURPOSE21"
>Purpose</A
></DT
><DT
><A
HREF="#SPECIFICOPTIONS12"
>Specific Options</A
></DT
></DL
></DD
><DT
><A
HREF="#USRLIBLIBRARIESFORPROGRAMMINGANDPA"
>/usr/lib : Libraries for programming and packages</A
></DT
><DD
><DL
><DT
><A
HREF="#PURPOSE22"
>Purpose</A
></DT
><DT
><A
HREF="#SPECIFICOPTIONS13"
>Specific Options</A
></DT
></DL
></DD
><DT
><A
HREF="#USRLIBLTQUALGTALTERNATEFORMATLIBRARI"
>/usr/lib&lt;qual&gt; : Alternate format libraries (optional)</A
></DT
><DD
><DL
><DT
><A
HREF="#PURPOSE23"
>Purpose</A
></DT
><DT
><A
HREF="#USRLOCALLOCALHIERARCHY"
>/usr/local : Local hierarchy</A
></DT
></DL
></DD
><DT
><A
HREF="#USRLOCALSHARE1"
>/usr/local/share</A
></DT
><DT
><A
HREF="#USRSBINNONESSENTIALSTANDARDSYSTEMBI"
>/usr/sbin : Non-essential standard system binaries</A
></DT
><DD
><DL
><DT
><A
HREF="#PURPOSE25"
>Purpose</A
></DT
></DL
></DD
><DT
><A
HREF="#USRSHAREARCHITECTUREINDEPENDENTDATA"
>/usr/share : Architecture-independent data</A
></DT
><DD
><DL
><DT
><A
HREF="#PURPOSE26"
>Purpose</A
></DT
><DT
><A
HREF="#REQUIREMENTS11"
>Requirements</A
></DT
><DT
><A
HREF="#SPECIFICOPTIONS15"
>Specific Options</A
></DT
><DT
><A
HREF="#USRSHAREDICTWORDLISTS"
>/usr/share/dict : Word lists (optional)</A
></DT
><DT
><A
HREF="#USRSHAREMANMANUALPAGES"
>/usr/share/man : Manual pages</A
></DT
><DT
><A
HREF="#USRSHAREMISCMISCELLANEOUSARCHITECTURE"
>/usr/share/misc : Miscellaneous architecture-independent data</A
></DT
><DT
><A
HREF="#USRSHARESGMLSGMLANDXMLDATA"
>/usr/share/sgml : SGML data (optional)</A
></DT
><DT
><A
HREF="#AEN2007"
>/usr/share/xml : XML data (optional)</A
></DT
></DL
></DD
><DT
><A
HREF="#USRSRCSOURCECODE"
>/usr/src : Source code (optional)</A
></DT
><DD
><DL
><DT
><A
HREF="#PURPOSE30"
>Purpose</A
></DT
></DL
></DD
></DL
></DD
><DT
>5. <A
HREF="#THEVARHIERARCHY"
>The /var Hierarchy</A
></DT
><DD
><DL
><DT
><A
HREF="#PURPOSE31"
>Purpose</A
></DT
><DT
><A
HREF="#REQUIREMENTS12"
>Requirements</A
></DT
><DT
><A
HREF="#SPECIFICOPTIONS20"
>Specific Options</A
></DT
><DT
><A
HREF="#VARACCOUNTPROCESSACCOUNTINGLOGS"
>/var/account : Process accounting logs (optional)</A
></DT
><DD
><DL
><DT
><A
HREF="#PURPOSE32"
>Purpose</A
></DT
></DL
></DD
><DT
><A
HREF="#VARCACHEAPPLICATIONCACHEDATA"
>/var/cache : Application cache data</A
></DT
><DD
><DL
><DT
><A
HREF="#PURPOSE33"
>Purpose</A
></DT
><DT
><A
HREF="#SPECIFICOPTIONS21"
>Specific Options</A
></DT
><DT
><A
HREF="#VARCACHEFONTSLOCALLYGENERATEDFONTS"
>/var/cache/fonts : Locally-generated fonts (optional)</A
></DT
><DT
><A
HREF="#VARCACHEMANLOCALLYFORMATTEDMANUALPAG"
>/var/cache/man : Locally-formatted manual pages (optional)</A
></DT
></DL
></DD
><DT
><A
HREF="#VARCRASHSYSTEMCRASHDUMPS"
>/var/crash : System crash dumps (optional)</A
></DT
><DD
><DL
><DT
><A
HREF="#PURPOSE36"
>Purpose</A
></DT
></DL
></DD
><DT
><A
HREF="#VARGAMESVARIABLEGAMEDATA"
>/var/games : Variable game data (optional)</A
></DT
><DD
><DL
><DT
><A
HREF="#PURPOSE37"
>Purpose</A
></DT
></DL
></DD
><DT
><A
HREF="#VARLIBVARIABLESTATEINFORMATION"
>/var/lib : Variable state information</A
></DT
><DD
><DL
><DT
><A
HREF="#PURPOSE38"
>Purpose</A
></DT
><DT
><A
HREF="#REQUIREMENTS13"
>Requirements</A
></DT
><DT
><A
HREF="#SPECIFICOPTIONS23"
>Specific Options</A
></DT
><DT
><A
HREF="#VARLIBLTEDITORGTEDITORBACKUPFILESAN"
>/var/lib/&lt;editor&gt; : Editor backup files and state (optional)</A
></DT
><DT
><A
HREF="#VARLIBHWCLOCKSTATEDIRECTORYFORHWCLO"
>/var/lib/hwclock : State directory for hwclock (optional)</A
></DT
><DT
><A
HREF="#VARLIBMISCMISCELLANEOUSVARIABLEDATA"
>/var/lib/misc : Miscellaneous variable data</A
></DT
></DL
></DD
><DT
><A
HREF="#VARLOCKLOCKFILES"
>/var/lock : Lock files</A
></DT
><DD
><DL
><DT
><A
HREF="#PURPOSE42"
>Purpose</A
></DT
></DL
></DD
><DT
><A
HREF="#VARLOGLOGFILESANDDIRECTORIES"
>/var/log : Log files and directories</A
></DT
><DD
><DL
><DT
><A
HREF="#PURPOSE43"
>Purpose</A
></DT
><DT
><A
HREF="#SPECIFICOPTIONS24"
>Specific Options</A
></DT
></DL
></DD
><DT
><A
HREF="#VARMAILUSERMAILBOXFILES"
>/var/mail : User mailbox files (optional)</A
></DT
><DD
><DL
><DT
><A
HREF="#PURPOSE44"
>Purpose</A
></DT
></DL
></DD
><DT
><A
HREF="#VAROPTVARIABLEDATAFOROPT"
>/var/opt : Variable data for /opt</A
></DT
><DD
><DL
><DT
><A
HREF="#PURPOSE45"
>Purpose</A
></DT
></DL
></DD
><DT
><A
HREF="#VARRUNRUNTIMEVARIABLEDATA"
>/var/run : Run-time variable data</A
></DT
><DD
><DL
><DT
><A
HREF="#PURPOSE46"
>Purpose</A
></DT
><DT
><A
HREF="#REQUIREMENTS14"
>Requirements</A
></DT
></DL
></DD
><DT
><A
HREF="#VARSPOOLAPPLICATIONSPOOLDATA"
>/var/spool : Application spool data</A
></DT
><DD
><DL
><DT
><A
HREF="#PURPOSE47"
>Purpose</A
></DT
><DT
><A
HREF="#SPECIFICOPTIONS25"
>Specific Options</A
></DT
><DT
><A
HREF="#VARSPOOLLPDLINEPRINTERDAEMONPRINTQU"
>/var/spool/lpd : Line-printer daemon print queues (optional)</A
></DT
><DT
><A
HREF="#VARSPOOLRWHORWHODFILES"
>/var/spool/rwho : Rwhod files (optional)</A
></DT
></DL
></DD
><DT
><A
HREF="#VARTMPTEMPORARYFILESPRESERVEDBETWEE"
>/var/tmp : Temporary files preserved between system reboots</A
></DT
><DD
><DL
><DT
><A
HREF="#PURPOSE50"
>Purpose</A
></DT
></DL
></DD
><DT
><A
HREF="#VARYPNETWORKINFORMATIONSERVICE"
>/var/yp : Network Information Service (NIS) database files (optional)</A
></DT
><DD
><DL
><DT
><A
HREF="#PURPOSE51"
>Purpose</A
></DT
></DL
></DD
></DL
></DD
><DT
>6. <A
HREF="#OPERATINGSYSTEMSPECIFICANNEX"
>Operating System Specific Annex</A
></DT
><DD
><DL
><DT
><A
HREF="#LINUX"
>Linux</A
></DT
><DD
><DL
><DT
><A
HREF="#ROOTDIRECTORY"
>/ : Root directory</A
></DT
><DT
><A
HREF="#BINESSENTIALUSERCOMMANDBINARIES2"
>/bin : Essential user command binaries (for use by all users)</A
></DT
><DT
><A
HREF="#DEVDEVICESANDSPECIALFILES"
>/dev : Devices and special files</A
></DT
><DT
><A
HREF="#ETCHOSTSPECIFICSYSTEMCONFIGURATION2"
>/etc : Host-specific system configuration</A
></DT
><DT
><A
HREF="#LIB64"
>/lib64 and /lib32 : 64/32-bit libraries (architecture dependent)</A
></DT
><DT
><A
HREF="#PROCKERNELANDPROCESSINFORMATIONVIR"
>/proc : Kernel and process information virtual filesystem</A
></DT
><DT
><A
HREF="#SBINESSENTIALSYSTEMBINARIES"
>/sbin : Essential system binaries</A
></DT
><DT
><A
HREF="#USRINCLUDEHEADERFILESINCLUDEDBYCP"
>/usr/include : Header files included by C programs</A
></DT
><DT
><A
HREF="#USRSRCSOURCECODE2"
>/usr/src : Source code</A
></DT
><DT
><A
HREF="#VARSPOOLCRONCRONANDATJOBS"
>/var/spool/cron : cron and at jobs</A
></DT
></DL
></DD
></DL
></DD
><DT
>7. <A
HREF="#APPENDIX"
>Appendix</A
></DT
><DD
><DL
><DT
><A
HREF="#THEFHSMAILINGLIST"
>The FHS mailing list</A
></DT
><DT
><A
HREF="#BACKGROUNDOFTHEFHS"
>Background of the FHS</A
></DT
><DT
><A
HREF="#GENERALGUIDELINES"
>General Guidelines</A
></DT
><DT
><A
HREF="#SCOPE"
>Scope</A
></DT
><DT
><A
HREF="#ACKNOWLEDGMENTS"
>Acknowledgments</A
></DT
><DT
><A
HREF="#CONTRIBUTORS"
>Contributors</A
></DT
></DL
></DD
></DL
></DIV
><DIV
CLASS="CHAPTER"
><HR><H1
><A
NAME="INTRODUCTION"
></A
>Chapter 1. Introduction</H1
><DIV
CLASS="SECTION"
><H2
CLASS="SECTION"
><A
NAME="PURPOSE"
>Purpose</A
></H2
><P
>This standard enables:</P
><P
></P
><UL
><LI
><P
>Software to predict the location of installed files and
directories, and</P
></LI
><LI
><P
>Users to predict the location of installed files and
directories.</P
></LI
></UL
><P
>We do this by:</P
><P
></P
><UL
><LI
><P
>Specifying guiding principles for each area of the filesystem,</P
></LI
><LI
><P
>Specifying the minimum files and directories required,</P
></LI
><LI
><P
>Enumerating exceptions to the principles, and</P
></LI
><LI
><P
>Enumerating specific cases where there has been historical conflict.</P
></LI
></UL
><P
>The FHS document is used by:</P
><P
></P
><UL
><LI
><P
>Independent software suppliers to create applications which are FHS
compliant, and work with distributions which are FHS complaint,</P
></LI
><LI
><P
>OS creators to provide systems which are FHS compliant, and</P
></LI
><LI
><P
>Users to understand and maintain the FHS compliance of a system.</P
></LI
></UL
><P
>The FHS document has a limited scope:</P
><P
></P
><UL
><LI
><P
>Local placement of local files is a local issue, so FHS does not
attempt to usurp system administrators.</P
></LI
><LI
><P
>FHS addresses issues where file placements need to be coordinated
between multiple parties such as local sites, distributions,
applications, documentation, etc.</P
></LI
></UL
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="CONVENTIONS"
>Conventions</A
></H2
><P
>We recommend that you read a typeset version of this document rather
than the plain text version.  In the typeset version, the names of files
and directories are displayed in a constant-width font.</P
><P
>Components of filenames that vary are represented by a description
of the contents enclosed in "<SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>&lt;</I
></SPAN
>" and
"<SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>&gt;</I
></SPAN
>" characters, <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>&lt;thus&gt;</I
></SPAN
>.  Electronic mail addresses are also
enclosed in "&lt;" and "&gt;" but are shown in the usual
typeface.</P
><P
>Optional components of filenames are enclosed in
"<SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>[</I
></SPAN
>" and "<SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>]</I
></SPAN
>" characters and may
be combined with the "<SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>&lt;</I
></SPAN
>" and
"<SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>&gt;</I
></SPAN
>" convention.  For example, if a filename is
allowed to occur either with or without an extension, it might be
represented by
<SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>&lt;filename&gt;[.&lt;extension&gt;]</I
></SPAN
>.</P
><P
>Variable substrings of directory names and filenames are indicated
by "<SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>*</I
></SPAN
>".</P
><P
>The sections of the text marked as
<SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>Rationale</I
></SPAN
> are explanatory and are
non-normative.</P
></DIV
></DIV
><DIV
CLASS="CHAPTER"
><HR><H1
><A
NAME="THEFILESYSTEM"
></A
>Chapter 2. The Filesystem</H1
><P
>This standard assumes that the operating system underlying an
FHS-compliant file system supports the same basic security features
found in most UNIX filesystems.</P
><P
>It is possible to define two independent distinctions among
files: shareable vs. unshareable and variable vs. static.  In general,
files that differ in either of these respects should be located in
different directories.  This makes it easy to store files with
different usage characteristics on different filesystems.</P
><P
>"Shareable" files are those that can be stored on one host
and used on others.  "Unshareable" files are those that are not
shareable.  For example, the files in user home directories are
shareable whereas device lock files are not.</P
><P
>"Static" files include binaries, libraries, documentation
files and other files that do not change without system administrator
intervention.  "Variable" files are files that are not static.</P
><DIV
CLASS="TIP"
><P
></P
><TABLE
CLASS="TIP"
WIDTH="100%"
BORDER="0"
><TR
><TD
WIDTH="25"
ALIGN="CENTER"
VALIGN="TOP"
><IMG
SRC="tip.gif"
HSPACE="5"
ALT="Tip"></TD
><TH
ALIGN="LEFT"
VALIGN="CENTER"
><B
>Rationale</B
></TH
></TR
><TR
><TD
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>Shareable files can be stored on one host and used on several
others.  Typically, however, not all files in the filesystem
hierarchy are shareable and so each system has local storage
containing at least its unshareable files.  It is convenient if all
the files a system requires that are stored on a foreign host can be
made available by mounting one or a few directories from the foreign
host.</P
><P
>Static and variable files should be segregated because static
files, unlike variable files, can be stored on read-only media and
do not need to be backed up on the same schedule as variable
files.</P
><P
>Historical UNIX-like filesystem hierarchies contained both
static and variable files under both <TT
CLASS="FILENAME"
>/usr</TT
> and
<TT
CLASS="FILENAME"
>/etc</TT
>.  In order to realize the advantages
mentioned above, the <TT
CLASS="FILENAME"
>/var</TT
> hierarchy was
created and all variable files were transferred from
<TT
CLASS="FILENAME"
>/usr</TT
> to <TT
CLASS="FILENAME"
>/var</TT
>.
Consequently <TT
CLASS="FILENAME"
>/usr</TT
> can now be mounted read-only
(if it is a separate filesystem).  Variable files have been
transferred from <TT
CLASS="FILENAME"
>/etc</TT
> to
<TT
CLASS="FILENAME"
>/var</TT
> over a longer period as technology has
permitted.</P
><P
>Here is an example of a FHS-compliant system.
(Other FHS-compliant layouts are possible.)</P
><DIV
CLASS="INFORMALTABLE"
><P
></P
><A
NAME="AEN103"
></A
><TABLE
BORDER="1"
FRAME="hsides"
CLASS="CALSTABLE"
><COL><COL><COL><THEAD
><TR
><TH
><SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
></I
></SPAN
></TH
><TH
>shareable</TH
><TH
>unshareable</TH
></TR
></THEAD
><TBODY
><TR
><TD
>static</TD
><TD
>/usr</TD
><TD
>/etc</TD
></TR
><TR
><TD
>&nbsp;</TD
><TD
>/opt</TD
><TD
>/boot</TD
></TR
><TR
><TD
>variable</TD
><TD
>/var/mail</TD
><TD
>/var/run</TD
></TR
><TR
><TD
>&nbsp;</TD
><TD
>/var/spool/news</TD
><TD
>/var/lock</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
></TD
></TR
></TABLE
></DIV
></DIV
><DIV
CLASS="CHAPTER"
><HR><H1
><A
NAME="THEROOTFILESYSTEM"
></A
>Chapter 3. The Root Filesystem</H1
><DIV
CLASS="SECTION"
><H2
CLASS="SECTION"
><A
NAME="PURPOSE2"
>Purpose</A
></H2
><P
>The contents of the root filesystem must be adequate to boot,
restore, recover, and/or repair the system.</P
><P
></P
><UL
><LI
STYLE="list-style-type: disc"
><P
>To boot a system, enough must be present on the root partition
to mount other filesystems.  This includes utilities, configuration,
boot loader information, and other essential start-up data.
<TT
CLASS="FILENAME"
>/usr</TT
>, <TT
CLASS="FILENAME"
>/opt</TT
>, and
<TT
CLASS="FILENAME"
>/var</TT
> are designed such that they may be located
on other partitions or filesystems.</P
></LI
><LI
STYLE="list-style-type: disc"
><P
>To enable recovery and/or repair of a system, those utilities
needed by an experienced maintainer to diagnose and reconstruct a
damaged system must be present on the root filesystem.</P
></LI
><LI
STYLE="list-style-type: disc"
><P
>To restore a system, those utilities needed to restore from
system backups (on floppy, tape, etc.) must be present on the root
filesystem.</P
></LI
></UL
><DIV
CLASS="TIP"
><P
></P
><TABLE
CLASS="TIP"
WIDTH="100%"
BORDER="0"
><TR
><TD
WIDTH="25"
ALIGN="CENTER"
VALIGN="TOP"
><IMG
SRC="tip.gif"
HSPACE="5"
ALT="Tip"></TD
><TH
ALIGN="LEFT"
VALIGN="CENTER"
><B
>Rationale</B
></TH
></TR
><TR
><TD
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>The primary concern used to balance these considerations, which
favor placing many things on the root filesystem, is the goal of
keeping root as small as reasonably possible.  For several reasons, it
is desirable to keep the root filesystem small:</P
><P
></P
><UL
><LI
><P
>It is occasionally mounted from very small media.</P
></LI
><LI
><P
>The root filesystem contains many system-specific configuration
files.  Possible examples include a kernel that is specific to the
system, a specific hostname, etc.  This means that the root filesystem
isn't always shareable between networked systems.  Keeping it small on
servers in networked systems minimizes the amount of lost space for
areas of unshareable files.  It also allows workstations with smaller
local hard drives.</P
></LI
><LI
><P
>While you may have the root filesystem on a large partition, and
may be able to fill it to your heart's content, there will be people
with smaller partitions.  If you have more files installed, you may
find incompatibilities with other systems using root filesystems on
smaller partitions.  If you are a developer then you may be turning
your assumption into a problem for a large number of users.</P
></LI
><LI
><P
>Disk errors that corrupt data on the root filesystem are a
greater problem than errors on any other partition.  A small root
filesystem is less prone to corruption as the result of a system
crash.</P
></LI
></UL
></TD
></TR
></TABLE
></DIV
><P
>Applications must never create or require special files or
subdirectories in the root directory.  Other locations in the FHS
hierarchy provide more than enough flexibility for any package.</P
><DIV
CLASS="TIP"
><P
></P
><TABLE
CLASS="TIP"
WIDTH="100%"
BORDER="0"
><TR
><TD
WIDTH="25"
ALIGN="CENTER"
VALIGN="TOP"
><IMG
SRC="tip.gif"
HSPACE="5"
ALT="Tip"></TD
><TH
ALIGN="LEFT"
VALIGN="CENTER"
><B
>Rationale</B
></TH
></TR
><TR
><TD
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>There are several reasons why creating a new subdirectory of
the root filesystem is prohibited:</P
><P
></P
><UL
><LI
STYLE="list-style-type: disc"
><P
>It demands space on a root partition which the system
administrator may want kept small and simple for either performance or
security reasons.</P
></LI
><LI
STYLE="list-style-type: disc"
><P
>It evades whatever discipline the system administrator may have
set up for distributing standard file hierarchies across mountable
volumes.</P
></LI
></UL
><P
>Distributions should not create new directories in the root
hierarchy without extremely careful consideration of the consequences
including for application portability.</P
></TD
></TR
></TABLE
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="REQUIREMENTS"
>Requirements</A
></H2
><P
>The following directories, or symbolic links to directories, are
required in <TT
CLASS="FILENAME"
>/</TT
>.</P
><DIV
CLASS="INFORMALTABLE"
><P
></P
><A
NAME="AEN169"
></A
><TABLE
BORDER="0"
FRAME="void"
CLASS="CALSTABLE"
><COL><COL><THEAD
><TR
><TH
>Directory</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><TT
CLASS="FILENAME"
>bin</TT
></TD
><TD
>Essential command binaries</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>boot</TT
></TD
><TD
>Static files of the boot loader</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>dev</TT
></TD
><TD
>Device files</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>etc</TT
></TD
><TD
>Host-specific system configuration</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>lib</TT
></TD
><TD
>Essential shared libraries and kernel modules</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>media</TT
></TD
><TD
>Mount point for removeable media</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>mnt</TT
></TD
><TD
>Mount point for mounting a filesystem temporarily</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>opt</TT
></TD
><TD
>Add-on application software packages</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>sbin</TT
></TD
><TD
>Essential system binaries</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>srv</TT
></TD
><TD
>Data for services provided by this system</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>tmp</TT
></TD
><TD
>Temporary files</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>usr</TT
></TD
><TD
>Secondary hierarchy</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>var</TT
></TD
><TD
>Variable data</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
><P
>Each directory listed above is specified in detail in separate
subsections below.  <TT
CLASS="FILENAME"
>/usr</TT
> and
<TT
CLASS="FILENAME"
>/var</TT
> each have a complete section in this
document due to the complexity of those directories.</P
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="SPECIFICOPTIONS"
>Specific Options</A
></H2
><P
>The following directories, or symbolic links to directories,
must be in <TT
CLASS="FILENAME"
>/</TT
>, if the corresponding subsystem is
installed:</P
><DIV
CLASS="INFORMALTABLE"
><P
></P
><A
NAME="AEN235"
></A
><TABLE
BORDER="0"
FRAME="void"
CLASS="CALSTABLE"
><COL><COL><THEAD
><TR
><TH
>Directory</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><TT
CLASS="FILENAME"
>home</TT
></TD
><TD
>User home directories (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>lib&lt;qual&gt;</TT
></TD
><TD
>Alternate format essential shared libraries (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>root</TT
></TD
><TD
>Home directory for the root user (optional)</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
><P
>Each directory listed above is specified in detail in separate
subsections below.</P
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="BINESSENTIALUSERCOMMANDBINARIES"
>/bin : Essential user command binaries (for use by all users)</A
></H2
><DIV
CLASS="SECTION"
><H3
CLASS="SECTION"
><A
NAME="PURPOSE3"
>Purpose</A
></H3
><P
><TT
CLASS="FILENAME"
>/bin</TT
> contains commands that may be used by
both the system administrator and by users, but which are required
when no other filesystems are mounted (e.g. in single user mode).  It
may also contain commands which are used indirectly by scripts.


<A
Filesystem Hierarchy Standard Group
NAME="AEN261"
HREF="#FTN.AEN261"
><SPAN
CLASS="footnote"
>[1]</SPAN
></A
></P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="REQUIREMENTS2"
>Requirements</A
></H3
><P
>There must be no subdirectories in
<TT
CLASS="FILENAME"
>/bin</TT
>.</P
><P
>The following commands, or symbolic links to commands, are
required in <TT
CLASS="FILENAME"
>/bin</TT
>.</P
><DIV
CLASS="INFORMALTABLE"
><P
></P
><A
NAME="AEN272"
></A
><TABLE
BORDER="0"
FRAME="void"
CLASS="CALSTABLE"
><COL><COL><THEAD
><TR
><TH
>Command</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><B
CLASS="COMMAND"
>cat</B
></TD
><TD
>Utility to concatenate files to standard output</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>chgrp</B
></TD
><TD
>Utility to change file group ownership</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>chmod</B
></TD
><TD
>Utility to change file access permissions</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>chown</B
></TD
><TD
>Utility to change file owner and group</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>cp</B
></TD
><TD
>Utility to copy files and directories</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>date</B
></TD
><TD
>Utility to print or set the system data and time</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>dd</B
></TD
><TD
>Utility to convert and copy a file</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>df</B
></TD
><TD
>Utility to report filesystem disk space usage</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>dmesg</B
></TD
><TD
>Utility to print or control the kernel message buffer</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>echo</B
></TD
><TD
>Utility to display a line of text</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>false</B
></TD
><TD
>Utility to do nothing, unsuccessfully</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>hostname</B
></TD
><TD
>Utility to show or set the system's host name</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>kill</B
></TD
><TD
>Utility to send signals to processes</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>ln</B
></TD
><TD
>Utility to make links between files</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>login</B
></TD
><TD
>Utility to begin a session on the system</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>ls</B
></TD
><TD
>Utility to list directory contents</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>mkdir</B
></TD
><TD
>Utility to make directories</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>mknod</B
></TD
><TD
>Utility to make block or character special files</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>more</B
></TD
><TD
>Utility to page through text</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>mount</B
></TD
><TD
>Utility to mount a filesystem</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>mv</B
></TD
><TD
>Utility to move/rename files</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>ps</B
></TD
><TD
>Utility to report process status</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>pwd</B
></TD
><TD
>Utility to print name of current working directory</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>rm</B
></TD
><TD
>Utility to remove files or directories</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>rmdir</B
></TD
><TD
>Utility to remove empty directories</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>sed</B
></TD
><TD
>The `sed' stream editor</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>sh</B
></TD
><TD
>The Bourne command shell</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>stty</B
></TD
><TD
>Utility to change and print terminal line settings</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>su</B
></TD
><TD
>Utility to change user ID</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>sync</B
></TD
><TD
>Utility to flush filesystem buffers</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>true</B
></TD
><TD
>Utility to do nothing, successfully</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>umount</B
></TD
><TD
>Utility to unmount file systems</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>uname</B
></TD
><TD
>Utility to print system information</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
><P
>If <B
CLASS="COMMAND"
>/bin/sh</B
> is not a true Bourne shell, it
must be a hard or symbolic link to the real shell command.</P
><P
>The <B
CLASS="COMMAND"
>[</B
> and <B
CLASS="COMMAND"
>test</B
>
commands must be placed together in either <TT
CLASS="FILENAME"
>/bin</TT
>
or <TT
CLASS="FILENAME"
>/usr/bin</TT
>.</P
><DIV
CLASS="TIP"
><P
></P
><TABLE
CLASS="TIP"
WIDTH="100%"
BORDER="0"
><TR
><TD
WIDTH="25"
ALIGN="CENTER"
VALIGN="TOP"
><IMG
SRC="tip.gif"
HSPACE="5"
ALT="Tip"></TD
><TH
ALIGN="LEFT"
VALIGN="CENTER"
><B
>Rationale</B
></TH
></TR
><TR
><TD
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>For example bash behaves differently when called as
<B
CLASS="COMMAND"
>sh</B
> or <B
CLASS="COMMAND"
>bash</B
>.  The use of a
symbolic link also allows users to easily see that
<B
CLASS="COMMAND"
>/bin/sh</B
> is not a true Bourne shell.</P
><P
>The requirement for the <B
CLASS="COMMAND"
>[</B
> and
<B
CLASS="COMMAND"
>test</B
> commands to be included as binaries (even if
implemented internally by the shell) is shared with the POSIX.2
standard.&#13;</P
></TD
></TR
></TABLE
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="SPECIFICOPTIONS2"
>Specific Options</A
></H3
><P
>The following programs, or symbolic links to programs, must be
in <TT
CLASS="FILENAME"
>/bin</TT
> if the corresponding subsystem is
installed:</P
><DIV
CLASS="INFORMALTABLE"
><P
></P
><A
NAME="AEN431"
></A
><TABLE
BORDER="0"
FRAME="void"
CLASS="CALSTABLE"
><COL><COL><THEAD
><TR
><TH
>Command</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><B
CLASS="COMMAND"
>csh</B
></TD
><TD
>The C shell (optional)</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>ed</B
></TD
><TD
>The `ed' editor (optional)</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>tar</B
></TD
><TD
>The tar archiving utility (optional)</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>cpio</B
></TD
><TD
>The cpio archiving utility (optional)</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>gzip</B
></TD
><TD
>The GNU compression utility (optional)</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>gunzip</B
></TD
><TD
>The GNU uncompression utility (optional)</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>zcat</B
></TD
><TD
>The GNU uncompression utility (optional)</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>netstat</B
></TD
><TD
>The network statistics utility (optional)</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>ping</B
></TD
><TD
>The ICMP network test utility (optional)</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
><P
>If the <B
CLASS="COMMAND"
>gunzip</B
> and <B
CLASS="COMMAND"
>zcat</B
>
programs exist, they must be symbolic or hard links to
gzip. <B
CLASS="COMMAND"
>/bin/csh</B
> may be a symbolic link to
<B
CLASS="COMMAND"
>/bin/tcsh</B
> or
<B
CLASS="COMMAND"
>/usr/bin/tcsh</B
>.</P
><DIV
CLASS="TIP"
><P
></P
><TABLE
CLASS="TIP"
WIDTH="100%"
BORDER="0"
><TR
><TD
WIDTH="25"
ALIGN="CENTER"
VALIGN="TOP"
><IMG
SRC="tip.gif"
HSPACE="5"
ALT="Tip"></TD
><TH
ALIGN="LEFT"
VALIGN="CENTER"
><B
>Rationale</B
></TH
></TR
><TR
><TD
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>The tar, gzip and cpio commands have been added to make restoration of a
system possible (provided that <TT
CLASS="FILENAME"
>/</TT
> is intact).</P
><P
>Conversely, if no restoration from the root partition is ever
expected, then these binaries might be omitted (e.g., a ROM chip root,
mounting <TT
CLASS="FILENAME"
>/usr</TT
> through NFS).  If restoration of a
system is planned through the network, then <B
CLASS="COMMAND"
>ftp</B
>
or <B
CLASS="COMMAND"
>tftp</B
> (along with everything necessary to get
an ftp connection) must be available on the root partition.&#13;</P
></TD
></TR
></TABLE
></DIV
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="BOOTSTATICFILESOFTHEBOOTLOADER"
>/boot : Static files of the boot loader</A
></H2
><DIV
CLASS="SECTION"
><H3
CLASS="SECTION"
><A
NAME="PURPOSE4"
>Purpose</A
></H3
><P
>This directory contains everything required for the boot process
except configuration files not needed at boot time and the map
installer. Thus /boot stores data that is used before the kernel
begins executing user-mode programs.  This may include saved master
boot sectors and sector map files.


<A
Edited by
NAME="AEN493"
HREF="#FTN.AEN493"
><SPAN
CLASS="footnote"
>[2]</SPAN
></A
>&#13;</P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="SPECIFICOPTIONS3"
>Specific Options</A
></H3
><P
>The operating system kernel must be located in either
<TT
CLASS="FILENAME"
>/</TT
> or <TT
CLASS="FILENAME"
>/boot</TT
>.


<A
Rusty Russell
NAME="AEN507"
HREF="#FTN.AEN507"
><SPAN
CLASS="footnote"
>[3]</SPAN
></A
></P
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="DEVDEVICEFILES"
>/dev : Device files</A
></H2
><DIV
CLASS="SECTION"
><H3
CLASS="SECTION"
><A
NAME="PURPOSE5"
>Purpose</A
></H3
><P
>The <TT
CLASS="FILENAME"
>/dev</TT
> directory is the location of
special or device files.</P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="SPECIFICOPTIONS4"
>Specific Options</A
></H3
><P
>If it is possible that devices in <TT
CLASS="FILENAME"
>/dev</TT
> will
need to be manually created, <TT
CLASS="FILENAME"
>/dev</TT
> must contain a
command named <TT
CLASS="FILENAME"
>MAKEDEV</TT
>, which can create devices
as needed.  It may also contain a <TT
CLASS="FILENAME"
>MAKEDEV.local</TT
>
for any local devices.</P
><P
>If required, <TT
CLASS="FILENAME"
>MAKEDEV</TT
> must have provisions
for creating any device that may be found on the system, not just
those that a particular implementation installs.</P
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="ETCHOSTSPECIFICSYSTEMCONFIGURATION"
>/etc : Host-specific system configuration</A
></H2
><DIV
CLASS="SECTION"
><H3
CLASS="SECTION"
><A
NAME="PURPOSE6"
>Purpose</A
></H3
><P
>The <TT
CLASS="FILENAME"
>/etc</TT
> hierarchy contains configuration
files.  A "configuration file" is a local file used to control the
operation of a program; it must be static and cannot be an executable
binary.


<A
Daniel Quinlan
NAME="AEN534"
HREF="#FTN.AEN534"
><SPAN
CLASS="footnote"
>[4]</SPAN
></A
></P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="REQUIREMENTS3"
>Requirements</A
></H3
><P
>No binaries may be located under <TT
CLASS="FILENAME"
>/etc</TT
>.


<A
Christopher Yeoh
NAME="AEN540"
HREF="#FTN.AEN540"
><SPAN
CLASS="footnote"
>[5]</SPAN
></A
></P
><P
>The following directories, or symbolic links to directories are
required in <TT
CLASS="FILENAME"
>/etc</TT
>:</P
><DIV
CLASS="INFORMALTABLE"
><P
></P
><A
NAME="AEN546"
></A
><TABLE
BORDER="0"
FRAME="void"
CLASS="CALSTABLE"
><COL><COL><THEAD
><TR
><TH
>Directory</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
>opt</TD
><TD
>Configuration for /opt</TD
></TR
><TR
><TD
>X11</TD
><TD
>Configuration for the X Window system (optional)</TD
></TR
><TR
><TD
>sgml</TD
><TD
>Configuration for SGML (optional)</TD
></TR
><TR
><TD
>xml</TD
><TD
>Configuration for XML (optional)</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="SPECIFICOPTIONS5"
>Specific Options</A
></H3
><P
>The following directories, or symbolic links to directories must
be in <TT
CLASS="FILENAME"
>/etc</TT
>, if the corresponding subsystem is
installed:</P
><DIV
CLASS="INFORMALTABLE"
><P
></P
><A
NAME="AEN569"
></A
><TABLE
BORDER="0"
FRAME="void"
CLASS="CALSTABLE"
><COL><COL><THEAD
><TR
><TH
>Directory</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
>opt</TD
><TD
>Configuration for /opt</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
><P
>The following files, or symbolic links to files, must be in
<TT
CLASS="FILENAME"
>/etc</TT
> if the corresponding subsystem is
installed:


<A
Copyright © 1994-2004 Daniel Quinlan
NAME="AEN581"
HREF="#FTN.AEN581"
><SPAN
CLASS="footnote"
>[6]</SPAN
></A
></P
><DIV
CLASS="INFORMALTABLE"
><P
></P
><A
NAME="AEN588"
></A
><TABLE
BORDER="0"
FRAME="void"
CLASS="CALSTABLE"
><COL><COL><THEAD
><TR
><TH
>File</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><TT
CLASS="FILENAME"
>csh.login</TT
></TD
><TD
>Systemwide initialization file for C shell logins (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>exports</TT
></TD
><TD
>NFS filesystem access control list (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>fstab</TT
></TD
><TD
>Static information about filesystems (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>ftpusers</TT
></TD
><TD
>FTP daemon user access control list (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>gateways</TT
></TD
><TD
>File which lists gateways for routed (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>gettydefs</TT
></TD
><TD
>Speed and terminal settings used by getty (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>group</TT
></TD
><TD
>User group file (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>host.conf</TT
></TD
><TD
>Resolver configuration file (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>hosts</TT
></TD
><TD
>Static information about host names (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>hosts.allow</TT
></TD
><TD
>Host access file for TCP wrappers (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>hosts.deny</TT
></TD
><TD
>Host access file for TCP wrappers (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>hosts.equiv</TT
></TD
><TD
>List of trusted hosts for rlogin, rsh, rcp (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>hosts.lpd</TT
></TD
><TD
>List of trusted hosts for lpd (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>inetd.conf</TT
></TD
><TD
>Configuration file for inetd (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>inittab</TT
></TD
><TD
>Configuration file for init (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>issue</TT
></TD
><TD
>Pre-login message and identification file (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>ld.so.conf</TT
></TD
><TD
>List of extra directories to search for shared libraries (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>motd</TT
></TD
><TD
>Post-login message of the day file (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>mtab</TT
></TD
><TD
>Dynamic information about filesystems (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>mtools.conf</TT
></TD
><TD
>Configuration file for mtools (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>networks</TT
></TD
><TD
>Static information about network names (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>passwd</TT
></TD
><TD
>The password file (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>printcap</TT
></TD
><TD
>The lpd printer capability database (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>profile</TT
></TD
><TD
>Systemwide initialization file for sh shell logins (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>protocols</TT
></TD
><TD
>IP protocol listing (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>resolv.conf</TT
></TD
><TD
>Resolver configuration file (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>rpc</TT
></TD
><TD
>RPC protocol listing (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>securetty</TT
></TD
><TD
>TTY access control for root login (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>services</TT
></TD
><TD
>Port names for network services (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>shells</TT
></TD
><TD
>Pathnames of valid login shells (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>syslog.conf</TT
></TD
><TD
>Configuration file for syslogd (optional)</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
><P
><TT
CLASS="FILENAME"
>mtab</TT
> does not fit the static nature of
<TT
CLASS="FILENAME"
>/etc</TT
>: it is excepted for historical reasons.


<A
Copyright © 2001-2004 Paul 'Rusty' Russell
NAME="AEN722"
HREF="#FTN.AEN722"
><SPAN
CLASS="footnote"
>[7]</SPAN
></A
>&#13;</P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="ETCOPTCONFIGURATIONFILESFOROPT"
>/etc/opt : Configuration files for /opt</A
></H3
><DIV
CLASS="SECTION"
><H4
CLASS="SECTION"
><A
NAME="PURPOSE7"
>Purpose</A
></H4
><P
>Host-specific configuration files for add-on application
software packages must be installed within the directory
<TT
CLASS="FILENAME"
>/etc/opt/&lt;subdir&gt;</TT
>, where
<TT
CLASS="FILENAME"
>&lt;subdir&gt;</TT
> is the name of the subtree in
<TT
CLASS="FILENAME"
>/opt</TT
> where the static data from that package is
stored.</P
></DIV
><DIV
CLASS="SECTION"
><HR><H4
CLASS="SECTION"
><A
NAME="REQUIREMENTS4"
>Requirements</A
></H4
><P
>No structure is imposed on the internal arrangement of
<TT
CLASS="FILENAME"
>/etc/opt/&lt;subdir&gt;</TT
>.</P
><P
>If a configuration file must reside in a different location in
order for the package or system to function properly, it may be placed
in a location other than
<TT
CLASS="FILENAME"
>/etc/opt/&lt;subdir&gt;</TT
>.</P
><DIV
CLASS="TIP"
><P
></P
><TABLE
CLASS="TIP"
WIDTH="100%"
BORDER="0"
><TR
><TD
WIDTH="25"
ALIGN="CENTER"
VALIGN="TOP"
><IMG
SRC="tip.gif"
HSPACE="5"
ALT="Tip"></TD
><TH
ALIGN="LEFT"
VALIGN="CENTER"
><B
>Rationale</B
></TH
></TR
><TR
><TD
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>Refer to the rationale for <TT
CLASS="FILENAME"
>/opt</TT
>.</P
></TD
></TR
></TABLE
></DIV
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="ETCX11CONFIGURATIONFORTHEXWINDOWS"
>/etc/X11 : Configuration for the X Window System (optional)</A
></H3
><DIV
CLASS="SECTION"
><H4
CLASS="SECTION"
><A
NAME="PURPOSE8"
>Purpose</A
></H4
><P
><SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>/etc/X11</I
></SPAN
> is the location for all X11
host-specific configuration.  This directory is necessary to allow
local control if <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>/usr</I
></SPAN
> is mounted read
only.</P
></DIV
><DIV
CLASS="SECTION"
><HR><H4
CLASS="SECTION"
><A
NAME="SPECIFICOPTIONS6"
>Specific Options</A
></H4
><P
>The following files, or symbolic links to files, must be in
<TT
CLASS="FILENAME"
>/etc/X11</TT
> if the corresponding subsystem is
installed:</P
><DIV
CLASS="INFORMALTABLE"
><P
></P
><A
NAME="AEN754"
></A
><TABLE
BORDER="0"
FRAME="void"
CLASS="CALSTABLE"
><COL
WIDTH="1*"
TITLE="C1"><COL
WIDTH="1*"
TITLE="C2"><THEAD
><TR
><TH
>File</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><TT
CLASS="FILENAME"
>Xconfig</TT
></TD
><TD
>The configuration file for early versions of XFree86 (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>XF86Config</TT
></TD
><TD
>The configuration file for XFree86 versions 3 and 4 (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>Xmodmap</TT
></TD
><TD
>Global X11 keyboard modification file (optional)</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
><P
>Subdirectories of <TT
CLASS="FILENAME"
>/etc/X11</TT
> may include
those for <TT
CLASS="FILENAME"
>xdm</TT
> and for any other programs (some
window managers, for example) that need them.


<A
Copyright © 2003-2004 Christopher Yeoh
NAME="AEN778"
HREF="#FTN.AEN778"
><SPAN
CLASS="footnote"
>[8]</SPAN
></A
>


We recommend that window managers with only one configuration file
This standard consists of a set of requirements and guidelines for file and
which is a default <TT
directory placement under UNIX-like operating systems. The guidelines are
CLASS="FILENAME"
intended to support interoperability of applications, system administration
>.*wmrc</TT
tools, development tools, and scripts as well as greater uniformity of
> file must name it
documentation for these systems.
<TT
CLASS="FILENAME"
>system.*wmrc</TT
> (unless there is a widely-accepted
alternative name) and not use a subdirectory.  Any window manager
subdirectories must be identically named to the actual window manager
binary.</P
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="ETCSGMLCONFIGURATIONFILESFORSGMLAN"
>/etc/sgml : Configuration files for SGML (optional)</A
></H3
><DIV
CLASS="SECTION"
><H4
CLASS="SECTION"
><A
NAME="PURPOSE9"
>Purpose</A
></H4
><P
>Generic configuration files defining high-level parameters of
the SGML systems are installed here. Files with names
<TT
CLASS="FILENAME"
>*.conf</TT
> indicate generic configuration files.
File with names <TT
CLASS="FILENAME"
>*.cat</TT
> are the DTD-specific
centralized catalogs, containing references to all other catalogs
needed to use the given DTD.  The super catalog file
<TT
CLASS="FILENAME"
>catalog</TT
> references all the centralized
catalogs.</P
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="AEN795"
>/etc/xml : Configuration files for XML (optional)</A
></H3
><DIV
CLASS="SECTION"
><H4
CLASS="SECTION"
><A
NAME="AEN797"
>Purpose</A
></H4
><P
>Generic configuration files defining high-level parameters of
the XML systems are installed here.  Files with names
<TT
CLASS="FILENAME"
>*.conf</TT
> indicate generic configuration files.
The super catalog file
<TT
CLASS="FILENAME"
>catalog</TT
> references all the centralized
catalogs.</P
></DIV
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="HOMEUSERHOMEDIRECTORIES"
>/home : User home directories (optional)</A
></H2
><DIV
CLASS="SECTION"
><H3
CLASS="SECTION"
><A
NAME="PURPOSE10"
>Purpose</A
></H3
><P
><TT
CLASS="FILENAME"
>/home</TT
> is a fairly standard concept, but it
is clearly a site-specific filesystem.


<A
All trademarks and copyrights are owned by their owners, unless specifically
NAME="AEN808"
noted otherwise. Use of a term in this document should not be regarded as
HREF="#FTN.AEN808"
affecting the validity of any trademark or service mark.
><SPAN
CLASS="footnote"
>[9]</SPAN
></A
>


The setup will differ from host to host.  Therefore, no program should
Permission is granted to make and distribute verbatim copies of this standard
rely on this location.
provided the copyright and this permission notice are preserved on all copies.


<A
Permission is granted to copy and distribute modified versions of this standard
NAME="AEN819"
under the conditions for verbatim copying, provided also that the title page is
HREF="#FTN.AEN819"
labeled as modified including a reference to the original standard, provided
><SPAN
that information on retrieving the original standard is included, and provided
CLASS="footnote"
that the entire resulting derived work is distributed under the terms of a
>[10]</SPAN
permission notice identical to this one.
></A
>&#13;</P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="REQUIREMENTS4A"
>Requirements</A
></H3
><P
>User specific configuration files for applications are stored in the
user's home directory in a file that starts with the '.' character (a
"dot file").  If an application needs to create more than one dot file
then they should be placed in a subdirectory with a name starting with
a '.' character, (a "dot directory").  In this case the configuration
files should not start with the '.' character.
<A
NAME="AEN826"
HREF="#FTN.AEN826"
><SPAN
CLASS="footnote"
>[11]</SPAN
></A
></P
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="LIBESSENTIALSHAREDLIBRARIESANDKERN"
>/lib : Essential shared libraries and kernel modules</A
></H2
><DIV
CLASS="SECTION"
><H3
CLASS="SECTION"
><A
NAME="PURPOSE11"
>Purpose</A
></H3
><P
>The <TT
CLASS="FILENAME"
>/lib</TT
> directory contains those shared
library images needed to boot the system and run the commands in the
root filesystem, ie. by binaries in <TT
CLASS="FILENAME"
>/bin</TT
> and
<TT
CLASS="FILENAME"
>/sbin</TT
>.


<A
Permission is granted to copy and distribute translations of this standard into
NAME="AEN836"
another language, under the above conditions for modified versions, except that
HREF="#FTN.AEN836"
this permission notice may be stated in a translation approved by the copyright
><SPAN
holder.
CLASS="footnote"
>[12]</SPAN
></A
></P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="REQUIREMENTS5"
>Requirements</A
></H3
><P
>At least one of each of the following filename patterns are
required (they may be files, or symbolic links):</P
><DIV
CLASS="INFORMALTABLE"
><P
></P
><A
NAME="AEN849"
></A
><TABLE
BORDER="0"
FRAME="void"
CLASS="CALSTABLE"
><COL><COL><THEAD
><TR
><TH
>File</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><TT
CLASS="FILENAME"
>libc.so.*</TT
></TD
><TD
>The dynamically-linked C library (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>ld*</TT
></TD
><TD
>The execution time linker/loader (optional)</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
><P
>If a C preprocessor is installed, <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>/lib/cpp</I
></SPAN
>
must be a reference to it, for historical reasons.


<A
[http://www.pathname.com/fhs/ Here] is the home of the Filesystem Hierarchy Standard (FHS). The copy you are reading is version 2.3. It was announced on January 29, 2004.
NAME="AEN866"
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
HREF="#FTN.AEN866"
><SPAN
CLASS="footnote"
>[13]</SPAN
></A
></P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="SPECIFICOPTIONS7"
>Specific Options</A
></H3
><P
>The following directories, or symbolic links to directories,
must be in <TT
CLASS="FILENAME"
>/lib</TT
>, if the corresponding subsystem
is installed:</P
><DIV
CLASS="INFORMALTABLE"
><P
></P
><A
NAME="AEN873"
></A
><TABLE
BORDER="0"
FRAME="void"
CLASS="CALSTABLE"
><COL><COL><THEAD
><TR
><TH
>Directory</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><TT
CLASS="FILENAME"
>modules</TT
></TD
><TD
>Loadable kernel modules (optional)</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="LIBLTQUALGTALTERNATEFORMATESSENTIAL"
>/lib&lt;qual&gt; : Alternate format essential shared libraries (optional)</A
></H2
><DIV
CLASS="SECTION"
><H3
CLASS="SECTION"
><A
NAME="PURPOSE12"
>Purpose</A
></H3
><P
>There may be one or more variants of the
<TT
CLASS="FILENAME"
>/lib</TT
> directory on systems which support more than
one binary format requiring separate libraries.


<A
Table of Contents
NAME="AEN890"
1. Introduction
HREF="#FTN.AEN890"
><SPAN
CLASS="footnote"
>[14]</SPAN
></A
></P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="REQUIREMENTS6"
>Requirements</A
></H3
><P
>If one or more of these directories exist, the requirements for
their contents are the same as the normal <TT
CLASS="FILENAME"
>/lib</TT
>
directory, except that <TT
CLASS="FILENAME"
>/lib&lt;qual&gt;/cpp</TT
> is
not required.


<A
    Purpose
NAME="AEN900"
    Conventions
HREF="#FTN.AEN900"
><SPAN
CLASS="footnote"
>[15]</SPAN
></A
></P
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="MEDIAMOUNTPOINT"
>/media : Mount point for removeable media</A
></H2
><DIV
CLASS="SECTION"
><H3
CLASS="SECTION"
><A
NAME="PURPOSEMEDIAMOUNTPOINT"
>Purpose</A
></H3
><P
>This directory contains subdirectories which are used as mount
points for removeable media such as floppy disks, cdroms and zip
disks.</P
><DIV
CLASS="TIP"
><P
></P
><TABLE
CLASS="TIP"
WIDTH="100%"
BORDER="0"
><TR
><TD
WIDTH="25"
ALIGN="CENTER"
VALIGN="TOP"
><IMG
SRC="tip.gif"
HSPACE="5"
ALT="Tip"></TD
><TH
ALIGN="LEFT"
VALIGN="CENTER"
><B
>Rationale</B
></TH
></TR
><TR
><TD
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>Historically there have been a number of other different places
used to mount removeable media such as <TT
CLASS="FILENAME"
>/cdrom</TT
>,
<TT
CLASS="FILENAME"
>/mnt</TT
> or <TT
CLASS="FILENAME"
>/mnt/cdrom</TT
>. Placing
the mount points for all removeable media directly in the root
directory would potentially result in a large number of extra
directories in <TT
CLASS="FILENAME"
>/</TT
>. Although the use of
subdirectories in <TT
CLASS="FILENAME"
>/mnt</TT
> as a mount point has
recently been common, it conflicts with a much older tradition of
using <TT
CLASS="FILENAME"
>/mnt</TT
> directly as a temporary mount point.</P
></TD
></TR
></TABLE
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="SPECIFICOPTIONSMEDIAMOUNT"
>Specific Options</A
></H3
><P
>The following directories, or symbolic links to directories,
must be in <TT
CLASS="FILENAME"
>/media</TT
>, if the corresponding subsystem
is installed:</P
><DIV
CLASS="INFORMALTABLE"
><P
></P
><A
NAME="AEN923"
></A
><TABLE
BORDER="0"
FRAME="void"
CLASS="CALSTABLE"
><COL><COL><THEAD
><TR
><TH
>Directory</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><TT
CLASS="FILENAME"
>floppy</TT
></TD
><TD
>Floppy drive (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>cdrom</TT
></TD
><TD
>CD-ROM drive (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>cdrecorder</TT
></TD
><TD
>CD writer (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>zip</TT
></TD
><TD
>Zip drive (optional)</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
><P
>On systems where more than one device exists for mounting a
certain type of media, mount directories can be created by appending a
digit to the name of those available above starting with '0', but the
unqualified name must also exist.


<A
2. The Filesystem
NAME="AEN947"
3. The Root Filesystem
HREF="#FTN.AEN947"
><SPAN
CLASS="footnote"
>[16]</SPAN
></A
>&#13;</P
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="MNTMOUNTPOINTFORATEMPORARILYMOUNT"
>/mnt : Mount point for a temporarily mounted filesystem</A
></H2
><DIV
CLASS="SECTION"
><H3
CLASS="SECTION"
><A
NAME="PURPOSE13"
>Purpose</A
></H3
><P
>This directory is provided so that the system administrator may
temporarily mount a filesystem as needed.  The content of this
directory is a local issue and should not affect the manner in which
any program is run.</P
><P
>This directory must not be used by installation programs: a
suitable temporary directory not in use by the system must be used
instead.</P
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="OPTADDONAPPLICATIONSOFTWAREPACKAGES"
>/opt : Add-on application software packages</A
></H2
><DIV
CLASS="SECTION"
><H3
CLASS="SECTION"
><A
NAME="PURPOSE14"
>Purpose</A
></H3
><P
><TT
CLASS="FILENAME"
>/opt</TT
> is reserved for the installation of
add-on application software packages.</P
><P
>A package to be installed in <TT
CLASS="FILENAME"
>/opt</TT
> must
locate its static files in a separate
<TT
CLASS="FILENAME"
>/opt/&lt;package&gt;</TT
> or
<TT
CLASS="FILENAME"
>/opt/&lt;provider&gt;</TT
> directory
tree, where <TT
CLASS="FILENAME"
>&lt;package&gt;</TT
> is a name that
describes the software package and
<TT
CLASS="FILENAME"
>&lt;provider&gt;</TT
> is the provider's LANANA
registered name.</P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="REQUIREMENTS7"
>Requirements</A
></H3
><DIV
CLASS="INFORMALTABLE"
><P
></P
><A
NAME="AEN972"
></A
><TABLE
BORDER="0"
FRAME="void"
CLASS="CALSTABLE"
><COL><COL><THEAD
><TR
><TH
>Directory</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
>&lt;package&gt;</TD
><TD
>Static package objects</TD
></TR
><TR
><TD
>&lt;provider&gt;</TD
><TD
>LANANA registered provider name</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
><P
>The directories <TT
CLASS="FILENAME"
>/opt/bin</TT
>,
<TT
CLASS="FILENAME"
>/opt/doc</TT
>, <TT
CLASS="FILENAME"
>/opt/include</TT
>,
<TT
CLASS="FILENAME"
>/opt/info</TT
>, <TT
CLASS="FILENAME"
>/opt/lib</TT
>, and
<TT
CLASS="FILENAME"
>/opt/man</TT
> are reserved for local system
administrator use.  Packages may provide "front-end" files intended to
be placed in (by linking or copying) these reserved directories by the
local system administrator, but must function normally in the absence
of these reserved directories.</P
><P
>Programs to be invoked by users must be located in the directory
<TT
CLASS="FILENAME"
>/opt/&lt;package&gt;/bin</TT
> or under the
<TT
CLASS="FILENAME"
>/opt/&lt;provider&gt;</TT
> hierarchy. If the package
includes UNIX manual pages, they must be located in
<TT
CLASS="FILENAME"
>/opt/&lt;package&gt;/share/man</TT
> or under the
<TT
CLASS="FILENAME"
>/opt/&lt;provider&gt;</TT
> hierarchy, and the same
substructure as <TT
CLASS="FILENAME"
>/usr/share/man</TT
> must be
used.</P
><P
>Package files that are variable (change in normal operation)
must be installed in <TT
CLASS="FILENAME"
>/var/opt</TT
>.  See the section
on <TT
CLASS="FILENAME"
>/var/opt</TT
> for more information.</P
><P
>Host-specific configuration files must be installed in
<TT
CLASS="FILENAME"
>/etc/opt</TT
>.  See the section on
<TT
CLASS="FILENAME"
>/etc</TT
> for more information.</P
><P
>No other package files may exist outside the
<TT
CLASS="FILENAME"
>/opt</TT
>, <TT
CLASS="FILENAME"
>/var/opt</TT
>, and
<TT
CLASS="FILENAME"
>/etc/opt</TT
> hierarchies except for those package
files that must reside in specific locations within the filesystem
tree in order to function properly.  For example, device lock files
must be placed in <TT
CLASS="FILENAME"
>/var/lock</TT
> and devices must be
located in <TT
CLASS="FILENAME"
>/dev</TT
>.</P
><P
>Distributions may install software in <TT
CLASS="FILENAME"
>/opt</TT
>,
but must not modify or delete software installed by the local system
administrator without the assent of the local system
administrator.</P
><DIV
CLASS="TIP"
><P
></P
><TABLE
CLASS="TIP"
WIDTH="100%"
BORDER="0"
><TR
><TD
WIDTH="25"
ALIGN="CENTER"
VALIGN="TOP"
><IMG
SRC="tip.gif"
HSPACE="5"
ALT="Tip"></TD
><TH
ALIGN="LEFT"
VALIGN="CENTER"
><B
>Rationale</B
></TH
></TR
><TR
><TD
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>The use of <TT
CLASS="FILENAME"
>/opt</TT
> for add-on software is a
well-established practice in the UNIX community.  The System V
Application Binary Interface [AT&amp;T 1990], based on the System V
Interface Definition (Third Edition), provides for an
<TT
CLASS="FILENAME"
>/opt</TT
> structure very similar to the one defined
here.</P
><P
>The Intel Binary Compatibility Standard v. 2 (iBCS2) also
provides a similar structure for <TT
CLASS="FILENAME"
>/opt</TT
>.</P
><P
>Generally, all data required to support a package on a system
must be present within <TT
CLASS="FILENAME"
>/opt/&lt;package&gt;</TT
>,
including files intended to be copied into
<TT
CLASS="FILENAME"
>/etc/opt/&lt;package&gt;</TT
> and
<TT
CLASS="FILENAME"
>/var/opt/&lt;package&gt;</TT
> as well as reserved
directories in <TT
CLASS="FILENAME"
>/opt</TT
>.</P
><P
>The minor restrictions on distributions using
<TT
CLASS="FILENAME"
>/opt</TT
> are necessary because conflicts are possible
between distribution-installed and locally-installed software,
especially in the case of fixed pathnames found in some binary
software.</P
><P
>The structure of the directories below
<TT
CLASS="FILENAME"
>/opt/&lt;provider&gt;</TT
> is left up to the packager
of the software, though it is recommended that packages are installed
in <TT
CLASS="FILENAME"
>/opt/&lt;provider&gt;/&lt;package&gt;</TT
> and
follow a similar structure to the guidelines for
<TT
CLASS="FILENAME"
>/opt/package</TT
>. A valid reason for diverging from
this structure is for support packages which may have files installed
in <TT
CLASS="FILENAME"
>/opt/&lt;provider&gt;/lib</TT
> or
<TT
CLASS="FILENAME"
>/opt/&lt;provider&gt;/bin</TT
>.</P
></TD
></TR
></TABLE
></DIV
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="ROOTHOMEDIRECTORYFORTHEROOTUSER"
>/root : Home directory for the root user (optional)</A
></H2
><DIV
CLASS="SECTION"
><H3
CLASS="SECTION"
><A
NAME="PURPOSE15"
>Purpose</A
></H3
><P
>The root account's home directory may be determined by developer
or local preference, but this is the recommended default
location.


<A
    Purpose
NAME="AEN1037"
    Requirements
HREF="#FTN.AEN1037"
    Specific Options
><SPAN
    /bin : Essential user command binaries (for use by all users)
CLASS="footnote"
>[17]</SPAN
></A
></P
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="SBINSYSTEMBINARIES"
>/sbin : System binaries</A
></H2
><DIV
CLASS="SECTION"
><H3
CLASS="SECTION"
><A
NAME="PURPOSE16"
>Purpose</A
></H3
><P
>Utilities used for system administration (and other root-only
commands) are stored in <TT
CLASS="FILENAME"
>/sbin</TT
>,
<TT
CLASS="FILENAME"
>/usr/sbin</TT
>, and
<TT
CLASS="FILENAME"
>/usr/local/sbin</TT
>.  <TT
CLASS="FILENAME"
>/sbin</TT
>
contains binaries essential for booting, restoring, recovering, and/or
repairing the system in addition to the binaries in
<TT
CLASS="FILENAME"
>/bin</TT
>.


<A
        Purpose
NAME="AEN1051"
        Requirements
HREF="#FTN.AEN1051"
        Specific Options
><SPAN
CLASS="footnote"
>[18]</SPAN
></A
> Programs executed after
<TT
CLASS="FILENAME"
>/usr</TT
> is known to be mounted (when there are no
problems) are generally placed into <TT
CLASS="FILENAME"
>/usr/sbin</TT
>.
Locally-installed system administration programs should be placed into
<TT
CLASS="FILENAME"
>/usr/local/sbin</TT
>.


<A
    /boot : Static files of the boot loader
NAME="AEN1058"
HREF="#FTN.AEN1058"
><SPAN
CLASS="footnote"
>[19]</SPAN
></A
></P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="REQUIREMENTS8"
>Requirements</A
></H3
><P
>The following commands, or symbolic links to commands, are
required in <TT
CLASS="FILENAME"
>/sbin</TT
>.</P
><DIV
CLASS="INFORMALTABLE"
><P
></P
><A
NAME="AEN1077"
></A
><TABLE
BORDER="0"
FRAME="void"
CLASS="CALSTABLE"
><COL><COL><THEAD
><TR
><TH
>Command</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><B
CLASS="COMMAND"
>shutdown</B
></TD
><TD
>Command to bring the system down.</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="SPECIFICOPTIONS8"
>Specific Options</A
></H3
><P
>The following files, or symbolic links to files, must be in
<TT
CLASS="FILENAME"
>/sbin</TT
> if the corresponding subsystem is
installed:</P
><DIV
CLASS="INFORMALTABLE"
><P
></P
><A
NAME="AEN1092"
></A
><TABLE
BORDER="0"
FRAME="void"
CLASS="CALSTABLE"
><COL
WIDTH="1*"
TITLE="C1"><COL
WIDTH="1*"
TITLE="C2"><THEAD
><TR
><TH
>Command</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><TT
CLASS="FILENAME"
>fastboot</TT
></TD
><TD
>Reboot the system without checking the disks (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>fasthalt</TT
></TD
><TD
>Stop the system without checking the disks (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>fdisk</TT
></TD
><TD
>Partition table manipulator (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>fsck</TT
></TD
><TD
>File system check and repair utility (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>fsck.*</TT
></TD
><TD
>File system check and repair utility for a specific filesystem (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>getty</TT
></TD
><TD
>The getty program (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>halt</TT
></TD
><TD
>Command to stop the system (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>ifconfig</TT
></TD
><TD
>Configure a network interface (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>init</TT
></TD
><TD
>Initial process (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>mkfs</TT
></TD
><TD
>Command to build a filesystem (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>mkfs.*</TT
></TD
><TD
>Command to build a specific filesystem (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>mkswap</TT
></TD
><TD
>Command to set up a swap area (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>reboot</TT
></TD
><TD
>Command to reboot the system (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>route</TT
></TD
><TD
>IP routing table utility (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>swapon</TT
></TD
><TD
>Enable paging and swapping (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>swapoff</TT
></TD
><TD
>Disable paging and swapping (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>update</TT
></TD
><TD
>Daemon to periodically flush filesystem buffers (optional)</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="SRVDATAFORSERVICESPROVIDEDBYSYSTEM"
>/srv : Data for services provided by this system</A
></H2
><DIV
CLASS="SECTION"
><H3
CLASS="SECTION"
><A
NAME="PURPOSE16A"
>Purpose</A
></H3
><P
><TT
CLASS="FILENAME"
>/srv</TT
> contains site-specific data which is
served by this system.


<DIV
        Purpose
CLASS="TIP"
        Specific Options
><P
></P
><TABLE
CLASS="TIP"
WIDTH="100%"
BORDER="0"
><TR
><TD
WIDTH="25"
ALIGN="CENTER"
VALIGN="TOP"
><IMG
SRC="tip.gif"
HSPACE="5"
ALT="Tip"></TD
><TH
ALIGN="LEFT"
VALIGN="CENTER"
><B
>Rationale</B
></TH
></TR
><TR
><TD
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>This main purpose of specifying this is so that users may find the
location of the data files for particular service, and so that
services which require a single tree for readonly data, writable data
and scripts (such as cgi scripts) can be reasonably placed. Data that
is only of interest to a specific user should go in that users' home
directory.</P
><P
>The methodology used to name subdirectories of
<TT
CLASS="FILENAME"
>/srv</TT
> is unspecified as there is currently no
consensus on how this should be done.  One method for structuring data
under <TT
CLASS="FILENAME"
>/srv</TT
> is by protocol,
eg. <TT
CLASS="FILENAME"
>ftp</TT
>, <TT
CLASS="FILENAME"
>rsync</TT
>,
<TT
CLASS="FILENAME"
>www</TT
>, and <TT
CLASS="FILENAME"
>cvs</TT
>. On large
systems it can be useful to structure <TT
CLASS="FILENAME"
>/srv</TT
> by
administrative context, such as <TT
CLASS="FILENAME"
>/srv/physics/www</TT
>,
<TT
CLASS="FILENAME"
>/srv/compsci/cvs</TT
>, etc. This setup will differ
from host to host. Therefore, no program should rely on a specific
subdirectory structure of <TT
CLASS="FILENAME"
>/srv</TT
> existing or data
necessarily being stored in <TT
CLASS="FILENAME"
>/srv</TT
>.  However
<TT
CLASS="FILENAME"
>/srv</TT
> should always exist on FHS compliant systems
and should be used as the default location for such data.</P
><P
>Distributions must take care not to remove locally placed files in
these directories without administrator permission.
<A
NAME="AEN1192"
HREF="#FTN.AEN1192"
><SPAN
CLASS="footnote"
>[20]</SPAN
></A
></P
></TD
></TR
></TABLE
></DIV
>&#13;</P
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="TMPTEMPORARYFILES"
>/tmp : Temporary files</A
></H2
><DIV
CLASS="SECTION"
><H3
CLASS="SECTION"
><A
NAME="PURPOSE17"
>Purpose</A
></H3
><P
>The <TT
CLASS="FILENAME"
>/tmp</TT
> directory must be made available
for programs that require temporary files.</P
><P
>Programs must not assume that any files or directories in
<TT
CLASS="FILENAME"
>/tmp</TT
> are preserved between invocations of the
program.</P
><DIV
CLASS="TIP"
><P
></P
><TABLE
CLASS="TIP"
WIDTH="100%"
BORDER="0"
><TR
><TD
WIDTH="25"
ALIGN="CENTER"
VALIGN="TOP"
><IMG
SRC="tip.gif"
HSPACE="5"
ALT="Tip"></TD
><TH
ALIGN="LEFT"
VALIGN="CENTER"
><B
>Rationale</B
></TH
></TR
><TR
><TD
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>IEEE standard P1003.2 (POSIX, part 2) makes requirements that
are similar to the above section.</P
><P
>Although data stored in <TT
CLASS="FILENAME"
>/tmp</TT
> may be deleted
in a site-specific manner, it is recommended that files and
directories located in <TT
CLASS="FILENAME"
>/tmp</TT
> be deleted whenever
the system is booted.</P
><P
>FHS added this recommendation on the basis of historical
precedent and common practice, but did not make it a requirement
because system administration is not within the scope of this
standard.&#13;</P
></TD
></TR
></TABLE
></DIV
></DIV
></DIV
></DIV
><DIV
CLASS="CHAPTER"
><HR><H1
><A
NAME="THEUSRHIERARCHY"
></A
>Chapter 4. The /usr Hierarchy</H1
><DIV
CLASS="SECTION"
><H2
CLASS="SECTION"
><A
NAME="PURPOSE18"
>Purpose</A
></H2
><P
><TT
CLASS="FILENAME"
>/usr</TT
> is the second major section of the
filesystem.  <TT
CLASS="FILENAME"
>/usr</TT
> is shareable, read-only data.
That means that <TT
CLASS="FILENAME"
>/usr</TT
> should be shareable between
various FHS-compliant hosts and must not be written to.  Any
information that is host-specific or varies with time is stored
elsewhere.</P
><P
>Large software packages must not use a direct subdirectory under
the <TT
CLASS="FILENAME"
>/usr</TT
> hierarchy.</P
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="REQUIREMENTS9"
>Requirements</A
></H2
><P
>The following directories, or symbolic links to directories, are
required in <TT
CLASS="FILENAME"
>/usr</TT
>.</P
><DIV
CLASS="INFORMALTABLE"
><P
></P
><A
NAME="AEN1223"
></A
><TABLE
BORDER="0"
FRAME="void"
CLASS="CALSTABLE"
><COL><COL><THEAD
><TR
><TH
>Directory</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><TT
CLASS="FILENAME"
>bin</TT
></TD
><TD
>Most user commands</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>include</TT
></TD
><TD
>Header files included by C programs</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>lib</TT
></TD
><TD
>Libraries</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>local</TT
></TD
><TD
>Local hierarchy (empty after main installation)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>sbin</TT
></TD
><TD
>Non-vital system binaries</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>share</TT
></TD
><TD
>Architecture-independent data</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="SPECIFICOPTIONS9"
>Specific Options</A
></H2
><DIV
CLASS="INFORMALTABLE"
><P
></P
><A
NAME="AEN1256"
></A
><TABLE
BORDER="0"
FRAME="void"
CLASS="CALSTABLE"
><COL><COL><THEAD
><TR
><TH
>Directory</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><TT
CLASS="FILENAME"
>X11R6</TT
></TD
><TD
>XWindow System, version 11 release 6 (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>games</TT
></TD
><TD
>Games and educational binaries (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>lib&lt;qual&gt;</TT
></TD
><TD
>Alternate Format Libraries (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>src</TT
></TD
><TD
>Source code (optional)</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
><P
>An exception is made for the X Window System because of
considerable precedent and widely-accepted practice.</P
><P
>The following symbolic links to directories may be present. This
possibility is based on the need to preserve compatibility with older
systems until all implementations can be assumed to use the
<TT
CLASS="FILENAME"
>/var</TT
> hierarchy.</P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="SCREEN"
>    /usr/spool -&gt; /var/spool
    /usr/tmp -&gt; /var/tmp
    /usr/spool/locks -&gt; /var/lock</PRE
></TD
></TR
></TABLE
><P
>Once a system no longer requires any one of the above symbolic links,
the link may be removed, if desired.</P
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="USRX11R6XWINDOWSYSTEMVERSION11REL"
>/usr/X11R6 : X Window System, Version 11 Release 6 (optional)</A
></H2
><DIV
CLASS="SECTION"
><H3
CLASS="SECTION"
><A
NAME="PURPOSE19"
>Purpose</A
></H3
><P
>This hierarchy is reserved for the X Window System, version 11
release 6, and related files.</P
><P
>To simplify matters and make XFree86 more compatible with the X
Window System on other systems, the following symbolic links must be
present if <TT
CLASS="FILENAME"
>/usr/X11R6</TT
> exists:</P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="SCREEN"
>    /usr/bin/X11 -&gt; /usr/X11R6/bin
    /usr/lib/X11 -&gt; /usr/X11R6/lib/X11
    /usr/include/X11 -&gt; /usr/X11R6/include/X11</PRE
></TD
></TR
></TABLE
><P
>In general, software must not be installed or managed via the above
symbolic links.  They are intended for utilization by users only.  The
difficulty is related to the release version of the X Window System &mdash;
in transitional periods, it is impossible to know what release of X11 is
in use.</P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="SPECIFICOPTIONS10"
>Specific Options</A
></H3
><P
>Host-specific data in <TT
CLASS="FILENAME"
>/usr/X11R6/lib/X11</TT
> should be interpreted
as a demonstration file.  Applications requiring information about the
current host must reference a configuration file in <TT
CLASS="FILENAME"
>/etc/X11</TT
>,
which may be linked to a file in <TT
CLASS="FILENAME"
>/usr/X11R6/lib</TT
>.


<A
    /dev : Device files
NAME="AEN1299"
HREF="#FTN.AEN1299"
><SPAN
CLASS="footnote"
>[21]</SPAN
></A
></P
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="USRBINMOSTUSERCOMMANDS"
>/usr/bin : Most user commands</A
></H2
><DIV
CLASS="SECTION"
><H3
CLASS="SECTION"
><A
NAME="PURPOSE20"
>Purpose</A
></H3
><P
>This is the primary directory of executable commands on the
system.</P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="SPECIFICOPTIONS11"
>Specific Options</A
></H3
><P
>The following directories, or symbolic links to directories,
must be in <TT
CLASS="FILENAME"
>/usr/bin</TT
>, if the corresponding
subsystem is installed:</P
><DIV
CLASS="INFORMALTABLE"
><P
></P
><A
NAME="AEN1313"
></A
><TABLE
BORDER="0"
FRAME="void"
CLASS="CALSTABLE"
><COL><COL><THEAD
><TR
><TH
>Directory</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><TT
CLASS="FILENAME"
>mh</TT
></TD
><TD
>Commands for the MH mail handling system (optional)</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
><P
><TT
CLASS="FILENAME"
>/usr/bin/X11</TT
> must be a symlink to
<TT
CLASS="FILENAME"
>/usr/X11R6/bin</TT
> if the latter exists.</P
><P
>The following files, or symbolic links to files, must be in
<TT
CLASS="FILENAME"
>/usr/bin</TT
>, if the corresponding subsystem is
installed:</P
><DIV
CLASS="INFORMALTABLE"
><P
></P
><A
NAME="AEN1329"
></A
><TABLE
BORDER="0"
FRAME="void"
CLASS="CALSTABLE"
><COL><COL><THEAD
><TR
><TH
>Command</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><B
CLASS="COMMAND"
>perl</B
></TD
><TD
>The Practical Extraction and Report Language (optional)</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>python</B
></TD
><TD
>The Python interpreted language (optional)</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>tclsh</B
></TD
><TD
>Simple shell containing Tcl interpreter (optional)</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>wish</B
></TD
><TD
>Simple Tcl/Tk windowing shell (optional)</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>expect</B
></TD
><TD
>Program for interactive dialog (optional)</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
><DIV
CLASS="TIP"
><P
></P
><TABLE
CLASS="TIP"
WIDTH="100%"
BORDER="0"
><TR
><TD
WIDTH="25"
ALIGN="CENTER"
VALIGN="TOP"
><IMG
SRC="tip.gif"
HSPACE="5"
ALT="Tip"></TD
><TH
ALIGN="LEFT"
VALIGN="CENTER"
><B
>Rationale</B
></TH
></TR
><TR
><TD
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>Because shell script interpreters (invoked with
<TT
CLASS="FILENAME"
>#!&lt;path&gt;</TT
> on the first line of a shell
script) cannot rely on a path, it is advantageous to standardize their
locations.  The Bourne shell and C-shell interpreters are already
fixed in <TT
CLASS="FILENAME"
>/bin</TT
>, but Perl, Python, and Tcl are
often found in many different places.  They may be symlinks to the
physical location of the shell interpreters.&#13;</P
></TD
></TR
></TABLE
></DIV
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="USRINCLUDEDIRECTORYFORSTANDARDINCLU"
>/usr/include : Directory for standard include files.</A
></H2
><DIV
CLASS="SECTION"
><H3
CLASS="SECTION"
><A
NAME="PURPOSE21"
>Purpose</A
></H3
><P
>This is where all of the system's general-use include files for the C
programming language should be placed.</P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="SPECIFICOPTIONS12"
>Specific Options</A
></H3
><P
>The following directories, or symbolic links to directories,
must be in <TT
CLASS="FILENAME"
>/usr/include</TT
>, if the corresponding
subsystem is installed:</P
><DIV
CLASS="INFORMALTABLE"
><P
></P
><A
NAME="AEN1370"
></A
><TABLE
BORDER="0"
FRAME="void"
CLASS="CALSTABLE"
><COL><COL><THEAD
><TR
><TH
>Directory</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
>bsd</TD
><TD
>BSD compatibility include files (optional)</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
><P
>The symbolic link <TT
CLASS="FILENAME"
>/usr/include/X11</TT
> must
link to <TT
CLASS="FILENAME"
>/usr/X11R6/include/X11</TT
> if the latter
exists.</P
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="USRLIBLIBRARIESFORPROGRAMMINGANDPA"
>/usr/lib : Libraries for programming and packages</A
></H2
><DIV
CLASS="SECTION"
><H3
CLASS="SECTION"
><A
NAME="PURPOSE22"
>Purpose</A
></H3
><P
><TT
CLASS="FILENAME"
>/usr/lib</TT
> includes object files, libraries,
and internal binaries that are not intended to be executed directly by
users or shell scripts.
<A
NAME="AEN1389"
HREF="#FTN.AEN1389"
><SPAN
CLASS="footnote"
>[22]</SPAN
></A
></P
><P
>Applications may use a single subdirectory under
<TT
CLASS="FILENAME"
>/usr/lib</TT
>.  If an application uses a subdirectory,
all architecture-dependent data exclusively used by the application
must be placed within that subdirectory. 


<A
        Purpose
NAME="AEN1394"
        Specific Options
HREF="#FTN.AEN1394"
><SPAN
CLASS="footnote"
>[23]</SPAN
></A
></P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="SPECIFICOPTIONS13"
>Specific Options</A
></H3
><P
>For historical reasons, <B
CLASS="COMMAND"
>/usr/lib/sendmail</B
>
must be a symbolic link to <B
CLASS="COMMAND"
>/usr/sbin/sendmail</B
> if
the latter exists.


<A
    /etc : Host-specific system configuration
NAME="AEN1402"
HREF="#FTN.AEN1402"
><SPAN
CLASS="footnote"
>[24]</SPAN
></A
></P
><P
>If <TT
CLASS="FILENAME"
>/lib/X11</TT
> exists,
<TT
CLASS="FILENAME"
>/usr/lib/X11</TT
> must be a symbolic link to
<TT
CLASS="FILENAME"
>/lib/X11</TT
>, or to whatever
<TT
CLASS="FILENAME"
>/lib/X11</TT
> is a symbolic link to.


<A
        Purpose
NAME="AEN1418"
        Requirements
HREF="#FTN.AEN1418"
        Specific Options
><SPAN
        /etc/opt : Configuration files for /opt
CLASS="footnote"
        /etc/X11 : Configuration for the X Window System (optional)
>[25]</SPAN
        /etc/sgml : Configuration files for SGML (optional)
></A
        /etc/xml : Configuration files for XML (optional)
></P
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="USRLIBLTQUALGTALTERNATEFORMATLIBRARI"
>/usr/lib&lt;qual&gt; : Alternate format libraries (optional)</A
></H2
><DIV
CLASS="SECTION"
><H3
CLASS="SECTION"
><A
NAME="PURPOSE23"
>Purpose</A
></H3
><P
><TT
CLASS="FILENAME"
>/usr/lib&lt;qual&gt;</TT
> performs the same role as <TT
CLASS="FILENAME"
>/usr/lib</TT
> for an
alternate binary format, except that the symbolic links
<TT
CLASS="FILENAME"
>/usr/lib&lt;qual&gt;/sendmail</TT
> and <TT
CLASS="FILENAME"
>/usr/lib&lt;qual&gt;/X11</TT
> are not required.


<A
    /home : User home directories (optional)
NAME="AEN1435"
HREF="#FTN.AEN1435"
><SPAN
CLASS="footnote"
>[26]</SPAN
></A
></P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="USRLOCALLOCALHIERARCHY"
>/usr/local : Local hierarchy</A
></H3
><DIV
CLASS="SECTION"
><H4
CLASS="SECTION"
><A
NAME="PURPOSE24"
>Purpose</A
></H4
><P
>The <TT
CLASS="FILENAME"
>/usr/local</TT
> hierarchy is for use by the
system administrator when installing software locally.  It needs to be
safe from being overwritten when the system software is updated.  It
may be used for programs and data that are shareable amongst a group
of hosts, but not found in <TT
CLASS="FILENAME"
>/usr</TT
>.</P
><P
>Locally installed software must be placed within
<TT
CLASS="FILENAME"
>/usr/local</TT
> rather than <TT
CLASS="FILENAME"
>/usr</TT
>
unless it is being installed to replace or upgrade software in
<TT
CLASS="FILENAME"
>/usr</TT
>.


<A
        Purpose
NAME="AEN1450"
        Requirements
HREF="#FTN.AEN1450"
><SPAN
CLASS="footnote"
>[27]</SPAN
></A
></P
></DIV
><DIV
CLASS="SECTION"
><HR><H4
CLASS="SECTION"
><A
NAME="REQUIREMENTS10"
>Requirements</A
></H4
><P
>The following directories, or symbolic links to directories,
must be in <TT
CLASS="FILENAME"
>/usr/local</TT
></P
><DIV
CLASS="INFORMALTABLE"
><P
></P
><A
NAME="AEN1460"
></A
><TABLE
BORDER="0"
FRAME="void"
CLASS="CALSTABLE"
><COL><COL><THEAD
><TR
><TH
>Directory</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><TT
CLASS="FILENAME"
>bin</TT
></TD
><TD
>Local binaries</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>etc</TT
></TD
><TD
>Host-specific system configuration for local binaries</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>games</TT
></TD
><TD
>Local game binaries</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>include</TT
></TD
><TD
>Local C header files</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>lib</TT
></TD
><TD
>Local libraries</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>man</TT
></TD
><TD
>Local online manuals</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>sbin</TT
></TD
><TD
>Local system binaries</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>share</TT
></TD
><TD
>Local architecture-independent hierarchy</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>src</TT
></TD
><TD
>Local source code</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
><P
>No other directories, except those listed below, may be in
<TT
CLASS="FILENAME"
>/usr/local</TT
> after first installing a FHS-compliant
system.</P
></DIV
><DIV
CLASS="SECTION"
><HR><H4
CLASS="SECTION"
><A
NAME="SPECIFICOPTIONS14"
>Specific Options</A
></H4
><P
>If directories <TT
CLASS="FILENAME"
>/lib&lt;qual&gt;</TT
> or
<TT
CLASS="FILENAME"
>/usr/lib&lt;qual&gt;</TT
> exist, the equivalent
directories must also exist in <TT
CLASS="FILENAME"
>/usr/local</TT
>.</P
><P
><TT
CLASS="FILENAME"
>/usr/local/etc</TT
> may be a symbolic link to
<TT
CLASS="FILENAME"
>/etc/local</TT
>.</P
><DIV
CLASS="TIP"
><P
></P
><TABLE
CLASS="TIP"
WIDTH="100%"
BORDER="0"
><TR
><TD
WIDTH="25"
ALIGN="CENTER"
VALIGN="TOP"
><IMG
SRC="tip.gif"
HSPACE="5"
ALT="Tip"></TD
><TH
ALIGN="LEFT"
VALIGN="CENTER"
><B
>Rationale</B
></TH
></TR
><TR
><TD
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>The consistency of <TT
CLASS="FILENAME"
>/usr/local/etc</TT
> is
beneficial to installers, and is already used in other systems.  As
all of <TT
CLASS="FILENAME"
>/usr/local</TT
> needs to be backed up to
reproduce a system, it introduces no additional maintenance overhead,
but a symlink to <TT
CLASS="FILENAME"
>/etc/local</TT
> is suitable if
systems want alltheir configuration under one hierarchy.</P
><P
>Note that <TT
CLASS="FILENAME"
>/usr/etc</TT
> is still not allowed: programs
in <TT
CLASS="FILENAME"
>/usr</TT
> should place configuration files in
<TT
CLASS="FILENAME"
>/etc</TT
>.</P
></TD
></TR
></TABLE
></DIV
></DIV
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="USRLOCALSHARE1"
>/usr/local/share</A
></H2
><P
>The requirements for the contents of this directory are the same
as <TT
CLASS="FILENAME"
>/usr/share</TT
>.  The only additional constraint is
that <TT
CLASS="FILENAME"
>/usr/local/share/man</TT
> and
<TT
CLASS="FILENAME"
>/usr/local/man</TT
> directories must be synonomous
(usually this means that one of them must be a symbolic link).


<A
    /lib : Essential shared libraries and kernel modules
NAME="AEN1530"
HREF="#FTN.AEN1530"
><SPAN
CLASS="footnote"
>[28]</SPAN
></A
></P
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="USRSBINNONESSENTIALSTANDARDSYSTEMBI"
>/usr/sbin : Non-essential standard system binaries</A
></H2
><DIV
CLASS="SECTION"
><H3
CLASS="SECTION"
><A
NAME="PURPOSE25"
>Purpose</A
></H3
><P
>This directory contains any non-essential binaries used
exclusively by the system administrator.  System administration
programs that are required for system repair, system recovery,
mounting <TT
CLASS="FILENAME"
>/usr</TT
>, or other essential functions must
be placed in <TT
CLASS="FILENAME"
>/sbin</TT
> instead.


<A
        Purpose
NAME="AEN1540"
        Requirements
HREF="#FTN.AEN1540"
        Specific Options
><SPAN
CLASS="footnote"
>[29]</SPAN
></A
></P
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="USRSHAREARCHITECTUREINDEPENDENTDATA"
>/usr/share : Architecture-independent data</A
></H2
><DIV
CLASS="SECTION"
><H3
CLASS="SECTION"
><A
NAME="PURPOSE26"
>Purpose</A
></H3
><P
>The <TT
CLASS="FILENAME"
>/usr/share</TT
> hierarchy is for all
read-only architecture independent data files.


<A
    /lib<qual> : Alternate format essential shared libraries (optional)
NAME="AEN1550"
HREF="#FTN.AEN1550"
><SPAN
CLASS="footnote"
>[30]</SPAN
></A
>&#13;</P
><P
>This hierarchy is intended to be shareable among all
architecture platforms of a given OS; thus, for example, a site with
i386, Alpha, and PPC platforms might maintain a single
<TT
CLASS="FILENAME"
>/usr/share</TT
> directory that is centrally-mounted.
Note, however, that <TT
CLASS="FILENAME"
>/usr/share</TT
> is generally not
intended to be shared by different OSes or by different releases of
the same OS.</P
><P
>Any program or package which contains or requires data that
doesn't need to be modified should store that data in
<TT
CLASS="FILENAME"
>/usr/share</TT
> (or
<TT
CLASS="FILENAME"
>/usr/local/share</TT
>, if installed locally).  It is
recommended that a subdirectory be used in
<TT
CLASS="FILENAME"
>/usr/share</TT
> for this purpose.</P
><P
>Game data stored in <TT
CLASS="FILENAME"
>/usr/share/games</TT
> must
be purely static data.  Any modifiable files, such as score files,
game play logs, and so forth, should be placed in
<TT
CLASS="FILENAME"
>/var/games</TT
>.</P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="REQUIREMENTS11"
>Requirements</A
></H3
><P
>The following directories, or symbolic links to directories,
must be in <TT
CLASS="FILENAME"
>/usr/share</TT
></P
><DIV
CLASS="INFORMALTABLE"
><P
></P
><A
NAME="AEN1573"
></A
><TABLE
BORDER="0"
FRAME="void"
CLASS="CALSTABLE"
><COL><COL><THEAD
><TR
><TH
>Directory</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><TT
CLASS="FILENAME"
>man</TT
></TD
><TD
>Online manuals</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>misc</TT
></TD
><TD
>Miscellaneous architecture-independent data</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="SPECIFICOPTIONS15"
>Specific Options</A
></H3
><P
>The following directories, or symbolic links to directories, must be in <TT
CLASS="FILENAME"
>/usr/share</TT
>, if the corresponding
subsystem is installed:</P
><DIV
CLASS="INFORMALTABLE"
><P
></P
><A
NAME="AEN1592"
></A
><TABLE
BORDER="0"
FRAME="void"
CLASS="CALSTABLE"
><COL><COL><THEAD
><TR
><TH
>Directory</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><TT
CLASS="FILENAME"
>dict</TT
></TD
><TD
>Word lists (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>doc</TT
></TD
><TD
>Miscellaneous documentation (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>games</TT
></TD
><TD
>Static data files for /usr/games (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>info</TT
></TD
><TD
>GNU Info system s primary directory (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>locale</TT
></TD
><TD
>Locale information (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>nls</TT
></TD
><TD
>Message catalogs for Native language support (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>sgml</TT
></TD
><TD
>SGML data (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>terminfo</TT
></TD
><TD
>Directories for terminfo database (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>tmac</TT
></TD
><TD
>troff macros not distributed with groff (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>xml</TT
></TD
><TD
>XML data (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>zoneinfo</TT
></TD
><TD
>Timezone information and configuration (optional)</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
><P
>It is recommended that application-specific,
architecture-independent directories be placed here.  Such directories
include <B
CLASS="COMMAND"
>groff</B
>, <B
CLASS="COMMAND"
>perl</B
>,
<B
CLASS="COMMAND"
>ghostscript</B
>, <B
CLASS="COMMAND"
>texmf</B
>, and
<B
CLASS="COMMAND"
>kbd</B
> (Linux) or <B
CLASS="COMMAND"
>syscons</B
>
(BSD).  They may, however, be placed in <TT
CLASS="FILENAME"
>/usr/lib</TT
>
for backwards compatibility, at the distributor's discretion.
Similarly, a <TT
CLASS="FILENAME"
>/usr/lib/games</TT
> hierarchy may be used
in addition to the <TT
CLASS="FILENAME"
>/usr/share/games</TT
> hierarchy if
the distributor wishes to place some game data there.</P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="USRSHAREDICTWORDLISTS"
>/usr/share/dict : Word lists (optional)</A
></H3
><DIV
CLASS="SECTION"
><H4
CLASS="SECTION"
><A
NAME="PURPOSE27"
>Purpose</A
></H4
><P
>This directory is the home for word lists on the system;
Traditionally this directory contains only the English
<TT
CLASS="FILENAME"
>words</TT
> file, which is used by
<B
CLASS="COMMAND"
>look(1)</B
> and various spelling programs.
<TT
CLASS="FILENAME"
>words</TT
> may use either American or British
spelling.</P
><DIV
CLASS="TIP"
><P
></P
><TABLE
CLASS="TIP"
WIDTH="100%"
BORDER="0"
><TR
><TD
WIDTH="25"
ALIGN="CENTER"
VALIGN="TOP"
><IMG
SRC="tip.gif"
HSPACE="5"
ALT="Tip"></TD
><TH
ALIGN="LEFT"
VALIGN="CENTER"
><B
>Rationale</B
></TH
></TR
><TR
><TD
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>The reason that only word lists are located here is that they
are the only files common to all spell checkers.</P
></TD
></TR
></TABLE
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H4
CLASS="SECTION"
><A
NAME="SPECIFICOPTIONS16"
>Specific Options</A
></H4
><P
>The following files, or symbolic links to files, must be in
<TT
CLASS="FILENAME"
>/usr/share/dict</TT
>, if the corresponding subsystem
is installed:</P
><DIV
CLASS="INFORMALTABLE"
><P
></P
><A
NAME="AEN1668"
></A
><TABLE
BORDER="0"
FRAME="void"
CLASS="CALSTABLE"
><COL><COL><THEAD
><TR
><TH
><TT
CLASS="FILENAME"
>File</TT
></TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><TT
CLASS="FILENAME"
>words</TT
></TD
><TD
>List of English words (optional)</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
><P
>Sites that require both American and British spelling may link
<TT
CLASS="FILENAME"
>words</TT
> to
<TT
CLASS="FILENAME"
>&shy;/usr/share/dict/american-english</TT
> or
<TT
CLASS="FILENAME"
>&shy;/usr/share/dict/british-english</TT
>.</P
><P
>Word lists for other languages may be added using the English
name for that language, e.g.,
<TT
CLASS="FILENAME"
>/usr/share/dict/french</TT
>,
<TT
CLASS="FILENAME"
>/usr/share/dict/danish</TT
>, etc.  These should, if
possible, use an ISO 8859 character set which is appropriate for the
language in question; if possible the Latin1 (ISO 8859-1) character
set should be used (this is often not possible).</P
><P
>Other word lists must be included here, if present.</P
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="USRSHAREMANMANUALPAGES"
>/usr/share/man : Manual pages</A
></H3
><DIV
CLASS="SECTION"
><H4
CLASS="SECTION"
><A
NAME="PURPOSE28"
>Purpose</A
></H4
><P
>This section details the organization for manual pages
throughout the system, including <TT
CLASS="FILENAME"
>/usr/share/man</TT
>.
Also refer to the section on
<TT
CLASS="FILENAME"
>/var/cache/man</TT
>.</P
><P
>The primary <TT
CLASS="FILENAME"
>&lt;mandir&gt;</TT
> of the system is
<TT
CLASS="FILENAME"
>/usr/share/man</TT
>.
<TT
CLASS="FILENAME"
>/usr/share/man</TT
> contains manual information for
commands and data under the <TT
CLASS="FILENAME"
>/</TT
> and
<TT
CLASS="FILENAME"
>/usr</TT
> filesystems.


<A
        Purpose
NAME="AEN1701"
        Requirements
HREF="#FTN.AEN1701"
><SPAN
CLASS="footnote"
>[31]</SPAN
></A
></P
><P
>Manual pages are stored in
<TT
CLASS="FILENAME"
>&lt;mandir&gt;/&lt;locale&gt;/man&lt;section&gt;/&lt;arch&gt;</TT
>.
An explanation of <TT
CLASS="FILENAME"
>&lt;mandir&gt;</TT
>,
<TT
CLASS="FILENAME"
>&lt;locale&gt;</TT
>,
<TT
CLASS="FILENAME"
>&lt;section&gt;</TT
>, and
<TT
CLASS="FILENAME"
>&lt;arch&gt;</TT
> is given below.</P
><P
>A description of each section follows:</P
><P
></P
><UL
><LI
STYLE="list-style-type: disc"
><P
><TT
CLASS="FILENAME"
>man1</TT
>: User programs
Manual pages that describe publicly accessible commands are contained in
this chapter.  Most program documentation that a user will need to use
is located here.</P
></LI
><LI
STYLE="list-style-type: disc"
><P
><TT
CLASS="FILENAME"
>man2</TT
>: System calls
This section describes all of the system calls (requests for the
kernel to perform operations).</P
></LI
><LI
STYLE="list-style-type: disc"
><P
><TT
CLASS="FILENAME"
>man3</TT
>: Library functions and subroutines
Section 3 describes program library routines that are not direct calls
to kernel services.  This and chapter 2 are only really of interest to
programmers.</P
></LI
><LI
STYLE="list-style-type: disc"
><P
><TT
CLASS="FILENAME"
>man4</TT
>: Special files
Section 4 describes the special files, related driver functions, and
networking support available in the system.  Typically, this includes
the device files found in <TT
CLASS="FILENAME"
>/dev</TT
> and the kernel interface to
networking protocol support.</P
></LI
><LI
STYLE="list-style-type: disc"
><P
><TT
CLASS="FILENAME"
>man5</TT
>: File formats
The formats for many data files are documented in the
section 5.  This includes various include files, program output files,
and system files.</P
></LI
><LI
STYLE="list-style-type: disc"
><P
><TT
CLASS="FILENAME"
>man6</TT
>: Games
This chapter documents games, demos, and generally trivial programs.
Different people have various notions about how essential this is.</P
></LI
><LI
STYLE="list-style-type: disc"
><P
><TT
CLASS="FILENAME"
>man7</TT
>: Miscellaneous
Manual pages that are difficult to classify are designated as being
section 7.  The troff and other text processing macro packages are found
here.</P
></LI
><LI
STYLE="list-style-type: disc"
><P
><TT
CLASS="FILENAME"
>man8</TT
>: System administration
Programs used by system administrators for system operation and
maintenance are documented here.  Some of these programs are also
occasionally useful for normal users.</P
></LI
></UL
></DIV
><DIV
CLASS="SECTION"
><HR><H4
CLASS="SECTION"
><A
NAME="SPECIFICOPTIONS17"
>Specific Options</A
></H4
><P
>The following directories, or symbolic links to directories,
must be in
<TT
CLASS="FILENAME"
>/usr/share/&lt;mandir&gt;/&lt;locale&gt;</TT
>, unless
they are empty:


<A
    /media : Mount point for removeable media
NAME="AEN1741"
HREF="#FTN.AEN1741"
><SPAN
CLASS="footnote"
>[32]</SPAN
></A
></P
><DIV
CLASS="INFORMALTABLE"
><P
></P
><A
NAME="AEN1745"
></A
><TABLE
BORDER="0"
FRAME="void"
CLASS="CALSTABLE"
><COL><COL><THEAD
><TR
><TH
>Directory</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><TT
CLASS="FILENAME"
>man1</TT
></TD
><TD
>User programs (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>man2</TT
></TD
><TD
>System calls (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>man3</TT
></TD
><TD
>Library calls (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>man4</TT
></TD
><TD
>Special files (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>man5</TT
></TD
><TD
>File formats (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>man6</TT
></TD
><TD
>Games (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>man7</TT
></TD
><TD
>Miscellaneous (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>man8</TT
></TD
><TD
>System administration (optional)</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
><P
>The component <TT
CLASS="FILENAME"
>&lt;section&gt;</TT
> describes the
manual section.</P
><P
>Provisions must be made in the structure of
<TT
CLASS="FILENAME"
>/usr/share/man</TT
> to support manual pages which are
written in different (or multiple) languages.  These provisions must
take into account the storage and reference of these manual pages.
Relevant factors include language (including geographical-based
differences), and character code set.</P
><P
>This naming of language subdirectories of
<TT
CLASS="FILENAME"
>/usr/share/man</TT
> is based on Appendix E of the
POSIX 1003.1 standard which describes the locale identification string
&mdash; the most well-accepted method to describe a cultural
environment.  The <TT
CLASS="FILENAME"
>&lt;locale&gt;</TT
> string
is:</P
><P
><TT
CLASS="FILENAME"
>&lt;language&gt;[_&lt;territory&gt;][.&lt;character-set&gt;][,&lt;version&gt;]</TT
></P
><P
>The <TT
CLASS="FILENAME"
>&lt;language&gt;</TT
> field must be taken
from ISO 639 (a code for the representation of names of languages).
It must be two characters wide and specified with lowercase letters
only.</P
><P
>The <TT
CLASS="FILENAME"
>&lt;territory&gt;</TT
> field must be the
two-letter code of ISO 3166 (a specification of representations of
countries), if possible.  (Most people are familiar with the
two-letter codes used for the country codes in email addresses.) It
must be two characters wide and specified with uppercase letters
only.
<A
NAME="AEN1797"
HREF="#FTN.AEN1797"
><SPAN
CLASS="footnote"
>[33]</SPAN
></A
></P
><P
>The <TT
CLASS="FILENAME"
>&lt;character-set&gt;</TT
> field must
represent the standard describing the character set.  If the
<TT
CLASS="FILENAME"
>&shy;&lt;character-set&gt;</TT
> field is just a
numeric specification, the number represents the number of the
international standard describing the character set.  It is
recommended that this be a numeric representation if possible (ISO
standards, especially), not include additional punctuation symbols,
and that any letters be in lowercase.</P
><P
>A parameter specifying a <TT
CLASS="FILENAME"
>&lt;version&gt;</TT
> of
the profile may be placed after the
<TT
CLASS="FILENAME"
>&shy;&lt;character-set&gt;</TT
> field, delimited by a
comma.  This may be used to discriminate between different cultural
needs; for instance, dictionary order versus a more systems-oriented
collating order.  This standard recommends not using the
<TT
CLASS="FILENAME"
>&lt;version&gt;</TT
> field, unless it is
necessary.</P
><P
>Systems which use a unique language and code set for all manual
pages may omit the <TT
CLASS="FILENAME"
>&lt;locale&gt;</TT
> substring and
store all manual pages in <TT
CLASS="FILENAME"
>&lt;mandir&gt;</TT
>.  For
example, systems which only have English manual pages coded with
ASCII, may store manual pages (the
<TT
CLASS="FILENAME"
>man&lt;section&gt;</TT
> directories) directly in
<TT
CLASS="FILENAME"
>/usr/share/man</TT
>.  (That is the traditional
circumstance and arrangement, in fact.)</P
><P
>Countries for which there is a well-accepted standard character
code set may omit the <TT
CLASS="FILENAME"
>&shy;&lt;character-set&gt;</TT
>
field, but it is strongly recommended that it be included, especially
for countries with several competing standards.</P
><P
>Various examples:</P
><DIV
CLASS="INFORMALTABLE"
><P
></P
><A
NAME="AEN1814"
></A
><TABLE
BORDER="0"
FRAME="void"
CLASS="CALSTABLE"
><COL
WIDTH="1*"
TITLE="C1"><COL
WIDTH="1*"
TITLE="C2"><COL
WIDTH="1*"
TITLE="C3"><COL
WIDTH="1*"
TITLE="C4"><THEAD
><TR
><TH
ALIGN="LEFT"
>Language</TH
><TH
ALIGN="LEFT"
>Territory</TH
><TH
ALIGN="LEFT"
>Character Set</TH
><TH
ALIGN="LEFT"
>Directory</TH
></TR
></THEAD
><TBODY
><TR
><TD
ALIGN="LEFT"
>English</TD
><TD
ALIGN="LEFT"
>&mdash;</TD
><TD
ALIGN="LEFT"
>ASCII</TD
><TD
ALIGN="LEFT"
>/usr/share/man/en</TD
></TR
><TR
><TD
ALIGN="LEFT"
>English</TD
><TD
ALIGN="LEFT"
>United Kingdom</TD
><TD
ALIGN="LEFT"
>ISO 8859-15</TD
><TD
ALIGN="LEFT"
>/usr/share/man/en_GB</TD
></TR
><TR
><TD
ALIGN="LEFT"
>English</TD
><TD
ALIGN="LEFT"
>United States</TD
><TD
ALIGN="LEFT"
>ASCII</TD
><TD
ALIGN="LEFT"
>/usr/share/man/en_US</TD
></TR
><TR
><TD
ALIGN="LEFT"
>French</TD
><TD
ALIGN="LEFT"
>Canada</TD
><TD
ALIGN="LEFT"
>ISO 8859-1</TD
><TD
ALIGN="LEFT"
>/usr/share/man/fr_CA</TD
></TR
><TR
><TD
ALIGN="LEFT"
>French</TD
><TD
ALIGN="LEFT"
>France</TD
><TD
ALIGN="LEFT"
>ISO 8859-1</TD
><TD
ALIGN="LEFT"
>/usr/share/man/fr_FR</TD
></TR
><TR
><TD
ALIGN="LEFT"
>German</TD
><TD
ALIGN="LEFT"
>Germany</TD
><TD
ALIGN="LEFT"
>ISO 646</TD
><TD
ALIGN="LEFT"
>/usr/share/man/de_DE.646</TD
></TR
><TR
><TD
ALIGN="LEFT"
>German</TD
><TD
ALIGN="LEFT"
>Germany</TD
><TD
ALIGN="LEFT"
>ISO 6937</TD
><TD
ALIGN="LEFT"
>/usr/share/man/de_DE.6937</TD
></TR
><TR
><TD
ALIGN="LEFT"
>German</TD
><TD
ALIGN="LEFT"
>Germany</TD
><TD
ALIGN="LEFT"
>ISO 8859-1</TD
><TD
ALIGN="LEFT"
>/usr/share/man/de_DE.88591</TD
></TR
><TR
><TD
ALIGN="LEFT"
>German</TD
><TD
ALIGN="LEFT"
>Switzerland</TD
><TD
ALIGN="LEFT"
>ISO 646</TD
><TD
ALIGN="LEFT"
>/usr/share/man/de_CH.646</TD
></TR
><TR
><TD
ALIGN="LEFT"
>Japanese</TD
><TD
ALIGN="LEFT"
>Japan</TD
><TD
ALIGN="LEFT"
>JIS</TD
><TD
ALIGN="LEFT"
>/usr/share/man/ja_JP.jis</TD
></TR
><TR
><TD
ALIGN="LEFT"
>Japanese</TD
><TD
ALIGN="LEFT"
>Japan</TD
><TD
ALIGN="LEFT"
>SJIS</TD
><TD
ALIGN="LEFT"
>/usr/share/man/ja_JP.sjis</TD
></TR
><TR
><TD
ALIGN="LEFT"
>Japanese</TD
><TD
ALIGN="LEFT"
>Japan</TD
><TD
ALIGN="LEFT"
>UJIS (or EUC-J)</TD
><TD
ALIGN="LEFT"
>/usr/share/man/ja_JP.ujis</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
><P
>Similarly, provision must be made for manual pages which are
architecture-dependent, such as documentation on device-drivers or
low-level system administration commands.  These must be placed under
an <TT
CLASS="FILENAME"
>&lt;arch&gt;</TT
> directory in the appropriate
<TT
CLASS="FILENAME"
>man&lt;section&gt;</TT
> directory; for example, a man
page for the i386 ctrlaltdel(8) command might be placed in
<TT
CLASS="FILENAME"
>/usr/share/man/&lt;locale&gt;/man8/i386/ctrlaltdel.8</TT
>.</P
><P
>Manual pages for commands and data under
<TT
CLASS="FILENAME"
>/usr/local</TT
> are stored in
<TT
CLASS="FILENAME"
>/usr/local/man</TT
>.  Manual pages for X11R6 are
stored in <TT
CLASS="FILENAME"
>/usr/X11R6/man</TT
>.  It follows that all
manual page hierarchies in the system must have the same structure as
<TT
CLASS="FILENAME"
>/usr/share/man</TT
>.</P
><P
>The cat page sections (<TT
CLASS="FILENAME"
>cat&lt;section&gt;</TT
>)
containing formatted manual page entries are also found within
subdirectories of <TT
CLASS="FILENAME"
>&lt;mandir&gt;/&lt;locale&gt;</TT
>,
but are not required nor may they be distributed in lieu of nroff
source manual pages.</P
><P
>The numbered sections "1" through "8" are traditionally defined.
In general, the file name for manual pages located within a particular
section end with <TT
CLASS="FILENAME"
>.&lt;section&gt;</TT
>.</P
><P
>In addition, some large sets of application-specific manual
pages have an additional suffix appended to the manual page filename.
For example, the MH mail handling system manual pages must have
<TT
CLASS="FILENAME"
>mh</TT
> appended to all MH manuals.  All X Window
System manual pages must have an <TT
CLASS="FILENAME"
>x</TT
> appended to
the filename.</P
><P
>The practice of placing various language manual pages in
appropriate subdirectories of <TT
CLASS="FILENAME"
>/usr/share/man</TT
> also
applies to the other manual page hierarchies, such as
<TT
CLASS="FILENAME"
>/usr/local/man</TT
> and
<TT
CLASS="FILENAME"
>/usr/X11R6/man</TT
>.  (This portion of the standard
also applies later in the section on the optional
<TT
CLASS="FILENAME"
>/var/cache/man</TT
> structure.)</P
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="USRSHAREMISCMISCELLANEOUSARCHITECTURE"
>/usr/share/misc : Miscellaneous architecture-independent data</A
></H3
><P
>This directory contains miscellaneous architecture-independent
files which don't require a separate subdirectory under
<TT
CLASS="FILENAME"
>/usr/share</TT
>.</P
><DIV
CLASS="SECTION"
><HR><H4
CLASS="SECTION"
><A
NAME="SPECIFICOPTIONS18"
>Specific Options</A
></H4
><P
>The following files, or symbolic links to files, must be in
<TT
CLASS="FILENAME"
>/usr/share/misc</TT
>, if the corresponding subsystem
is installed:</P
><DIV
CLASS="INFORMALTABLE"
><P
></P
><A
NAME="AEN1917"
></A
><TABLE
BORDER="0"
FRAME="void"
CLASS="CALSTABLE"
><COL
WIDTH="1*"
TITLE="C1"><COL
WIDTH="1*"
TITLE="C2"><THEAD
><TR
><TH
>File</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><TT
CLASS="FILENAME"
>ascii</TT
></TD
><TD
>ASCII character set table (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>magic</TT
></TD
><TD
>Default list of magic numbers for the file command (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>termcap</TT
></TD
><TD
>Terminal capability database (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>termcap.db</TT
></TD
><TD
>Terminal capability database (optional)</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
><P
>Other (application-specific) files may appear here, but a distributor
may place them in <TT
CLASS="FILENAME"
>/usr/lib</TT
> at their discretion.
<A
NAME="AEN1944"
HREF="#FTN.AEN1944"
><SPAN
CLASS="footnote"
>[34]</SPAN
></A
></P
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="USRSHARESGMLSGMLANDXMLDATA"
>/usr/share/sgml : SGML data (optional)</A
></H3
><DIV
CLASS="SECTION"
><H4
CLASS="SECTION"
><A
NAME="PURPOSE29"
>Purpose</A
></H4
><P
><TT
CLASS="FILENAME"
>/usr/share/sgml</TT
> contains
architecture-independent files used by SGML applications, such
as ordinary catalogs (not the centralized ones, see
<TT
CLASS="FILENAME"
>/etc/sgml</TT
>), DTDs, entities, or style
sheets.</P
></DIV
><DIV
CLASS="SECTION"
><HR><H4
CLASS="SECTION"
><A
NAME="SPECIFICOPTIONS19"
>Specific Options</A
></H4
><P
>The following directories, or symbolic links to directories,
must be in <TT
CLASS="FILENAME"
>/usr/share/sgml</TT
>, if the corresponding
subsystem is installed:</P
><DIV
CLASS="INFORMALTABLE"
><P
></P
><A
NAME="AEN1983"
></A
><TABLE
BORDER="0"
FRAME="void"
CLASS="CALSTABLE"
><COL><COL><THEAD
><TR
><TH
>Directory</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><TT
CLASS="FILENAME"
>docbook</TT
></TD
><TD
>docbook DTD (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>tei</TT
></TD
><TD
>tei DTD (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>html</TT
></TD
><TD
>html DTD (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>mathml</TT
></TD
><TD
>mathml DTD (optional)</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
><P
>Other files that are not specific to a given DTD may reside in
their own subdirectory.</P
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="AEN2007"
>/usr/share/xml : XML data (optional)</A
></H3
><DIV
CLASS="SECTION"
><H4
CLASS="SECTION"
><A
NAME="AEN2009"
>Purpose</A
></H4
><P
><TT
CLASS="FILENAME"
>/usr/share/xml</TT
> contains
architecture-independent files used by XML applications, such
as ordinary catalogs (not the centralized ones, see
<TT
CLASS="FILENAME"
>/etc/sgml</TT
>), DTDs, entities, or style
sheets.</P
></DIV
><DIV
CLASS="SECTION"
><HR><H4
CLASS="SECTION"
><A
NAME="AEN2014"
>Specific Options</A
></H4
><P
>The following directories, or symbolic links to directories,
must be in <TT
CLASS="FILENAME"
>/usr/share/xml</TT
>, if the corresponding
subsystem is installed:</P
><DIV
CLASS="INFORMALTABLE"
><P
></P
><A
NAME="AEN2018"
></A
><TABLE
BORDER="0"
FRAME="void"
CLASS="CALSTABLE"
><COL><COL><THEAD
><TR
><TH
>Directory</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><TT
CLASS="FILENAME"
>docbook</TT
></TD
><TD
>docbook XML DTD (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>xhtml</TT
></TD
><TD
>XHTML DTD (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>mathml</TT
></TD
><TD
>MathML DTD (optional)</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
></DIV
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="USRSRCSOURCECODE"
>/usr/src : Source code (optional)</A
></H2
><DIV
CLASS="SECTION"
><H3
CLASS="SECTION"
><A
NAME="PURPOSE30"
>Purpose</A
></H3
><P
>Source code may be place placed in this
subdirectory, only for reference purposes.


<A
        Purpose
NAME="AEN2042"
        Specific Options
HREF="#FTN.AEN2042"
 
><SPAN
    /mnt : Mount point for a temporarily mounted filesystem
CLASS="footnote"
 
>[35]</SPAN
        Purpose
></A
 
></P
    /opt : Add-on application software packages
></DIV
 
></DIV
        Purpose
></DIV
        Requirements
><DIV
 
CLASS="CHAPTER"
    /root : Home directory for the root user (optional)
><HR><H1
 
><A
        Purpose
NAME="THEVARHIERARCHY"
 
></A
    /sbin : System binaries
>Chapter 5. The /var Hierarchy</H1
 
><DIV
        Purpose
CLASS="SECTION"
        Requirements
><H2
        Specific Options
CLASS="SECTION"
 
><A
    /srv : Data for services provided by this system
NAME="PURPOSE31"
 
>Purpose</A
        Purpose
></H2
 
><P
    /tmp : Temporary files
><TT
 
CLASS="FILENAME"
        Purpose
>/var</TT
 
> contains variable data files.  This
4. The /usr Hierarchy
includes spool directories and files, administrative and logging data,
 
and transient and temporary files.</P
    Purpose
><P
    Requirements
>Some portions of <TT
    Specific Options
CLASS="FILENAME"
    /usr/X11R6 : X Window System, Version 11 Release 6 (optional)
>/var</TT
 
> are not shareable
        Purpose
between different systems.  For instance,
        Specific Options
<TT
 
CLASS="FILENAME"
    /usr/bin : Most user commands
>/var/log</TT
 
>, <TT
        Purpose
CLASS="FILENAME"
        Specific Options
>/var/lock</TT
 
>, and
    /usr/include : Directory for standard include files.
<TT
 
CLASS="FILENAME"
        Purpose
>/var/run</TT
        Specific Options
>.  Other portions may be shared, notably
 
<TT
    /usr/lib : Libraries for programming and packages
CLASS="FILENAME"
 
>/var/mail</TT
        Purpose
>, <TT
        Specific Options
CLASS="FILENAME"
 
>/var/cache/man</TT
    /usr/lib<qual> : Alternate format libraries (optional)
>,
 
<TT
        Purpose
CLASS="FILENAME"
        /usr/local : Local hierarchy
>/var/cache/fonts</TT
 
>, and
    /usr/local/share
<TT
    /usr/sbin : Non-essential standard system binaries
CLASS="FILENAME"
 
>/var/spool/news</TT
        Purpose
>.</P
 
><P
    /usr/share : Architecture-independent data
><TT
 
CLASS="FILENAME"
        Purpose
>/var</TT
        Requirements
> is specified here in order to make it
        Specific Options
possible to mount <TT
        /usr/share/dict : Word lists (optional)
CLASS="FILENAME"
        /usr/share/man : Manual pages
>/usr</TT
        /usr/share/misc : Miscellaneous architecture-independent data
> read-only.  Everything
        /usr/share/sgml : SGML data (optional)
that once went into <TT
        /usr/share/xml : XML data (optional)
CLASS="FILENAME"
 
>/usr</TT
    /usr/src : Source code (optional)
> that is written to
 
during system operation (as opposed to installation and software
        Purpose
maintenance) must be in <TT
 
CLASS="FILENAME"
5. The /var Hierarchy
>/var</TT
 
>.</P
    Purpose
><P
    Requirements
>If <TT
    Specific Options
CLASS="FILENAME"
    /var/account : Process accounting logs (optional)
>/var</TT
 
> cannot be made a separate
        Purpose
partition, it is often preferable to move <TT
 
CLASS="FILENAME"
    /var/cache : Application cache data
>/var</TT
 
>
        Purpose
out of the root partition and into the <TT
        Specific Options
CLASS="FILENAME"
        /var/cache/fonts : Locally-generated fonts (optional)
>/usr</TT
        /var/cache/man : Locally-formatted manual pages (optional)
>
 
partition.  (This is sometimes done to reduce the size of the root
    /var/crash : System crash dumps (optional)
partition or when space runs low in the root partition.)  However,
 
<TT
        Purpose
CLASS="FILENAME"
 
>/var</TT
    /var/games : Variable game data (optional)
> must not be linked to
 
<TT
        Purpose
CLASS="FILENAME"
 
>/usr</TT
    /var/lib : Variable state information
> because this makes separation of
 
<TT
        Purpose
CLASS="FILENAME"
        Requirements
>/usr</TT
        Specific Options
> and <TT
        /var/lib/<editor> : Editor backup files and state (optional)
CLASS="FILENAME"
        /var/lib/hwclock : State directory for hwclock (optional)
>/var</TT
        /var/lib/misc : Miscellaneous variable data
> more difficult
 
and is likely to create a naming conflict.  Instead, link
    /var/lock : Lock files
<TT
 
CLASS="FILENAME"
        Purpose
>/var</TT
 
> to <TT
    /var/log : Log files and directories
CLASS="FILENAME"
 
>/usr/var</TT
        Purpose
>.</P
        Specific Options
><P
 
>Applications must generally not add directories to the top level
    /var/mail : User mailbox files (optional)
of <TT
 
CLASS="FILENAME"
        Purpose
>/var</TT
 
>.  Such directories should only be added
    /var/opt : Variable data for /opt
if they have some system-wide implication, and in consultation with
 
the FHS mailing list.</P
        Purpose
></DIV
 
><DIV
    /var/run : Run-time variable data
CLASS="SECTION"
 
><HR><H2
        Purpose
CLASS="SECTION"
        Requirements
><A
 
NAME="REQUIREMENTS12"
    /var/spool : Application spool data
>Requirements</A
 
></H2
        Purpose
><P
        Specific Options
>The following directories, or symbolic links to directories, are
        /var/spool/lpd : Line-printer daemon print queues (optional)
required in <TT
        /var/spool/rwho : Rwhod files (optional)
CLASS="FILENAME"
 
>/var</TT
    /var/tmp : Temporary files preserved between system reboots
>.</P
 
><DIV
        Purpose
CLASS="INFORMALTABLE"
 
><P
    /var/yp : Network Information Service (NIS) database files (optional)
></P
 
><A
        Purpose
NAME="AEN2080"
 
></A
6. Operating System Specific Annex
><TABLE
 
BORDER="0"
    Linux
FRAME="void"
 
CLASS="CALSTABLE"
        / : Root directory
><COL><COL><THEAD
        /bin : Essential user command binaries (for use by all users)
><TR
        /dev : Devices and special files
><TH
        /etc : Host-specific system configuration
>Directory</TH
        /lib64 and /lib32 : 64/32-bit libraries (architecture dependent)
><TH
        /proc : Kernel and process information virtual filesystem
>Description</TH
        /sbin : Essential system binaries
></TR
        /usr/include : Header files included by C programs
></THEAD
        /usr/src : Source code
><TBODY
        /var/spool/cron : cron and at jobs
><TR
 
><TD
7. Appendix
><TT
 
CLASS="FILENAME"
    The FHS mailing list
>cache</TT
    Background of the FHS
></TD
    General Guidelines
><TD
    Scope
>Application cache data</TD
    Acknowledgments
></TR
    Contributors
><TR
 
><TD
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
><TT
 
CLASS="FILENAME"
Chapter 1. Introduction
>lib</TT
 
></TD
Purpose
><TD
 
>Variable state information</TD
This standard enables:
></TR
 
><TR
  • Software to predict the location of installed files and directories, and
><TD
 
><TT
  • Users to predict the location of installed files and directories.
CLASS="FILENAME"
 
>local</TT
We do this by:
></TD
 
><TD
  • Specifying guiding principles for each area of the filesystem,
>Variable data for /usr/local</TD
 
></TR
  • Specifying the minimum files and directories required,
><TR
 
><TD
  • Enumerating exceptions to the principles, and
><TT
 
CLASS="FILENAME"
  • Enumerating specific cases where there has been historical conflict.
>lock</TT
 
></TD
The FHS document is used by:
><TD
 
>Lock files</TD
  • Independent software suppliers to create applications which are FHS
></TR
    compliant, and work with distributions which are FHS complaint,
><TR
 
><TD
  • OS creators to provide systems which are FHS compliant, and
><TT
 
CLASS="FILENAME"
  • Users to understand and maintain the FHS compliance of a system.
>log</TT
 
></TD
The FHS document has a limited scope:
><TD
 
>Log files and directories</TD
  • Local placement of local files is a local issue, so FHS does not attempt to
></TR
    usurp system administrators.
><TR
 
><TD
  • FHS addresses issues where file placements need to be coordinated between
><TT
    multiple parties such as local sites, distributions, applications,
CLASS="FILENAME"
    documentation, etc.
>opt</TT
 
></TD
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
><TD
 
>Variable data for /opt</TD
Conventions
></TR
 
><TR
We recommend that you read a typeset version of this document rather than the
><TD
plain text version. In the typeset version, the names of files and directories
><TT
are displayed in a constant-width font.
CLASS="FILENAME"
 
>run</TT
Components of filenames that vary are represented by a description of the
></TD
contents enclosed in "<" and ">" characters, <thus>. Electronic mail addresses
><TD
are also enclosed in "<" and ">" but are shown in the usual typeface.
>Data relevant to running processes</TD
 
></TR
Optional components of filenames are enclosed in "[" and "]" characters and may
><TR
be combined with the "<" and ">" convention. For example, if a filename is
><TD
allowed to occur either with or without an extension, it might be represented
><TT
by <filename>[.<extension>].
CLASS="FILENAME"
 
>spool</TT
Variable substrings of directory names and filenames are indicated by "*".
></TD
 
><TD
The sections of the text marked as Rationale are explanatory and are
>Application spool data</TD
non-normative.
></TR
 
><TR
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
><TD
 
><TT
Chapter 2. The Filesystem
CLASS="FILENAME"
 
>tmp</TT
This standard assumes that the operating system underlying an FHS-compliant
></TD
file system supports the same basic security features found in most UNIX
><TD
filesystems.
>Temporary files preserved between system reboots</TD
 
></TR
It is possible to define two independent distinctions among files: shareable
></TBODY
vs. unshareable and variable vs. static. In general, files that differ in
></TABLE
either of these respects should be located in different directories. This makes
><P
it easy to store files with different usage characteristics on different
></P
filesystems.
></DIV
 
><P
"Shareable" files are those that can be stored on one host and used on others.
>Several directories are `reserved' in the sense that they must
"Unshareable" files are those that are not shareable. For example, the files in
not be used arbitrarily by some new application, since they would
user home directories are shareable whereas device lock files are not.
conflict with historical and/or local practice. They are:</P
 
><TABLE
"Static" files include binaries, libraries, documentation files and other files
BORDER="0"
that do not change without system administrator intervention. "Variable" files
BGCOLOR="#E0E0E0"
are files that are not static.
WIDTH="100%"
 
><TR
    Rationale: Shareable files can be stored on one host and used on several
><TD
    others. Typically, however, not all files in the filesystem hierarchy are
><PRE
    shareable and so each system has local storage containing at least its
CLASS="SCREEN"
    unshareable files. It is convenient if all the files a system requires that
>    /var/backups
    are stored on a foreign host can be made available by mounting one or a few
    directories from the foreign host.
 
    Static and variable files should be segregated because static files, unlike
    variable files, can be stored on read-only media and do not need to be
    backed up on the same schedule as variable files.
 
    Historical UNIX-like filesystem hierarchies contained both static and
    variable files under both /usr and /etc. In order to realize the advantages
    mentioned above, the /var hierarchy was created and all variable files were
    transferred from /usr to /var. Consequently /usr can now be mounted
    read-only (if it is a separate filesystem). Variable files have been
    transferred from /etc to /var over a longer period as technology has
    permitted.
 
    Here is an example of a FHS-compliant system. (Other FHS-compliant layouts
    are possible.)
 
    ┌────────┬───────────────┬───────────┐
    │        │  shareable  │unshareable│
    ├────────┼───────────────┼───────────┤
    │static  │/usr          │/etc      │
    ├────────┼───────────────┼───────────┤
    │        │/opt          │/boot      │
    ├────────┼───────────────┼───────────┤
    │variable│/var/mail      │/var/run  │
    ├────────┼───────────────┼───────────┤
    │        │/var/spool/news│/var/lock  │
    └────────┴───────────────┴───────────┘
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Chapter 3. The Root Filesystem
 
Purpose
 
The contents of the root filesystem must be adequate to boot, restore, recover,
and/or repair the system.
 
  • To boot a system, enough must be present on the root partition to mount
    other filesystems. This includes utilities, configuration, boot loader
    information, and other essential start-up data. /usr, /opt, and /var are
    designed such that they may be located on other partitions or filesystems.
 
  • To enable recovery and/or repair of a system, those utilities needed by an
    experienced maintainer to diagnose and reconstruct a damaged system must be
    present on the root filesystem.
 
  • To restore a system, those utilities needed to restore from system backups
    (on floppy, tape, etc.) must be present on the root filesystem.
 
    Rationale: The primary concern used to balance these considerations, which
    favor placing many things on the root filesystem, is the goal of keeping
    root as small as reasonably possible. For several reasons, it is desirable
    to keep the root filesystem small:
 
      □ It is occasionally mounted from very small media.
 
      □ The root filesystem contains many system-specific configuration files.
        Possible examples include a kernel that is specific to the system, a
        specific hostname, etc. This means that the root filesystem isn't
        always shareable between networked systems. Keeping it small on servers
        in networked systems minimizes the amount of lost space for areas of
        unshareable files. It also allows workstations with smaller local hard
        drives.
 
      □ While you may have the root filesystem on a large partition, and may be
        able to fill it to your heart's content, there will be people with
        smaller partitions. If you have more files installed, you may find
        incompatibilities with other systems using root filesystems on smaller
        partitions. If you are a developer then you may be turning your
        assumption into a problem for a large number of users.
 
      □ Disk errors that corrupt data on the root filesystem are a greater
        problem than errors on any other partition. A small root filesystem is
        less prone to corruption as the result of a system crash.
 
Applications must never create or require special files or subdirectories in
the root directory. Other locations in the FHS hierarchy provide more than
enough flexibility for any package.
 
    Rationale: There are several reasons why creating a new subdirectory of the
    root filesystem is prohibited:
 
      □ It demands space on a root partition which the system administrator may
        want kept small and simple for either performance or security reasons.
 
      □ It evades whatever discipline the system administrator may have set up
        for distributing standard file hierarchies across mountable volumes.
 
    Distributions should not create new directories in the root hierarchy
    without extremely careful consideration of the consequences including for
    application portability.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Requirements
 
The following directories, or symbolic links to directories, are required in /.
 
Directory                    Description
bin      Essential command binaries
boot      Static files of the boot loader
dev      Device files
etc      Host-specific system configuration
lib      Essential shared libraries and kernel modules
media    Mount point for removeable media
mnt      Mount point for mounting a filesystem temporarily
opt      Add-on application software packages
sbin      Essential system binaries
srv      Data for services provided by this system
tmp      Temporary files
usr      Secondary hierarchy
var      Variable data
 
Each directory listed above is specified in detail in separate subsections
below. /usr and /var each have a complete section in this document due to the
complexity of those directories.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Specific Options
 
The following directories, or symbolic links to directories, must be in /, if
the corresponding subsystem is installed:
 
Directory                      Description
home      User home directories (optional)
lib<qual> Alternate format essential shared libraries (optional)
root      Home directory for the root user (optional)
 
Each directory listed above is specified in detail in separate subsections
below.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/bin : Essential user command binaries (for use by all users)
 
Purpose
 
/bin contains commands that may be used by both the system administrator and by
users, but which are required when no other filesystems are mounted (e.g. in
single user mode). It may also contain commands which are used indirectly by
scripts. [1]
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Requirements
 
There must be no subdirectories in /bin.
 
The following commands, or symbolic links to commands, are required in /bin.
 
Command                      Description
cat      Utility to concatenate files to standard output
chgrp    Utility to change file group ownership
chmod    Utility to change file access permissions
chown    Utility to change file owner and group
cp      Utility to copy files and directories
date    Utility to print or set the system data and time
dd      Utility to convert and copy a file
df      Utility to report filesystem disk space usage
dmesg    Utility to print or control the kernel message buffer
echo    Utility to display a line of text
false    Utility to do nothing, unsuccessfully
hostname Utility to show or set the system's host name
kill    Utility to send signals to processes
ln      Utility to make links between files
login    Utility to begin a session on the system
ls      Utility to list directory contents
mkdir    Utility to make directories
mknod    Utility to make block or character special files
more    Utility to page through text
mount    Utility to mount a filesystem
mv      Utility to move/rename files
ps      Utility to report process status
pwd      Utility to print name of current working directory
rm      Utility to remove files or directories
rmdir    Utility to remove empty directories
sed      The `sed' stream editor
sh      The Bourne command shell
stty    Utility to change and print terminal line settings
su      Utility to change user ID
sync    Utility to flush filesystem buffers
true    Utility to do nothing, successfully
umount  Utility to unmount file systems
uname    Utility to print system information
 
If /bin/sh is not a true Bourne shell, it must be a hard or symbolic link to
the real shell command.
 
The [ and test commands must be placed together in either /bin or /usr/bin.
 
    Rationale: For example bash behaves differently when called as sh or bash.
    The use of a symbolic link also allows users to easily see that /bin/sh is
    not a true Bourne shell.
 
    The requirement for the [ and test commands to be included as binaries
    (even if implemented internally by the shell) is shared with the POSIX.2
    standard.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Specific Options
 
The following programs, or symbolic links to programs, must be in /bin if the
corresponding subsystem is installed:
 
Command                Description
csh    The C shell (optional)
ed      The `ed' editor (optional)
tar    The tar archiving utility (optional)
cpio    The cpio archiving utility (optional)
gzip    The GNU compression utility (optional)
gunzip  The GNU uncompression utility (optional)
zcat    The GNU uncompression utility (optional)
netstat The network statistics utility (optional)
ping    The ICMP network test utility (optional)
 
If the gunzip and zcat programs exist, they must be symbolic or hard links to
gzip. /bin/csh may be a symbolic link to /bin/tcsh or /usr/bin/tcsh.
 
    Rationale: The tar, gzip and cpio commands have been added to make
    restoration of a system possible (provided that / is intact).
 
    Conversely, if no restoration from the root partition is ever expected,
    then these binaries might be omitted (e.g., a ROM chip root, mounting /usr
    through NFS). If restoration of a system is planned through the network,
    then ftp or tftp (along with everything necessary to get an ftp connection)
    must be available on the root partition.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/boot : Static files of the boot loader
 
Purpose
 
This directory contains everything required for the boot process except
configuration files not needed at boot time and the map installer. Thus /boot
stores data that is used before the kernel begins executing user-mode programs.
This may include saved master boot sectors and sector map files. [2]
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Specific Options
 
The operating system kernel must be located in either / or /boot. [3]
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/dev : Device files
 
Purpose
 
The /dev directory is the location of special or device files.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Specific Options
 
If it is possible that devices in /dev will need to be manually created, /dev
must contain a command named MAKEDEV, which can create devices as needed. It
may also contain a MAKEDEV.local for any local devices.
 
If required, MAKEDEV must have provisions for creating any device that may be
found on the system, not just those that a particular implementation installs.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/etc : Host-specific system configuration
 
Purpose
 
The /etc hierarchy contains configuration files. A "configuration file" is a
local file used to control the operation of a program; it must be static and
cannot be an executable binary. [4]
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Requirements
 
No binaries may be located under /etc. [5]
 
The following directories, or symbolic links to directories are required in /
etc:
 
Directory                  Description
opt      Configuration for /opt
X11      Configuration for the X Window system (optional)
sgml      Configuration for SGML (optional)
xml      Configuration for XML (optional)
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Specific Options
 
The following directories, or symbolic links to directories must be in /etc, if
the corresponding subsystem is installed:
 
Directory      Description
opt      Configuration for /opt
 
The following files, or symbolic links to files, must be in /etc if the
corresponding subsystem is installed: [6]
 
  File                                Description
csh.login  Systemwide initialization file for C shell logins (optional)
exports    NFS filesystem access control list (optional)
fstab      Static information about filesystems (optional)
ftpusers    FTP daemon user access control list (optional)
gateways    File which lists gateways for routed (optional)
gettydefs  Speed and terminal settings used by getty (optional)
group      User group file (optional)
host.conf  Resolver configuration file (optional)
hosts      Static information about host names (optional)
hosts.allow Host access file for TCP wrappers (optional)
hosts.deny  Host access file for TCP wrappers (optional)
hosts.equiv List of trusted hosts for rlogin, rsh, rcp (optional)
hosts.lpd  List of trusted hosts for lpd (optional)
inetd.conf  Configuration file for inetd (optional)
inittab    Configuration file for init (optional)
issue      Pre-login message and identification file (optional)
ld.so.conf  List of extra directories to search for shared libraries (optional)
motd        Post-login message of the day file (optional)
mtab        Dynamic information about filesystems (optional)
mtools.conf Configuration file for mtools (optional)
networks    Static information about network names (optional)
passwd      The password file (optional)
printcap    The lpd printer capability database (optional)
profile    Systemwide initialization file for sh shell logins (optional)
protocols  IP protocol listing (optional)
resolv.conf Resolver configuration file (optional)
rpc        RPC protocol listing (optional)
securetty  TTY access control for root login (optional)
services    Port names for network services (optional)
shells      Pathnames of valid login shells (optional)
syslog.conf Configuration file for syslogd (optional)
 
mtab does not fit the static nature of /etc: it is excepted for historical
reasons. [7]
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/etc/opt : Configuration files for /opt
 
Purpose
 
Host-specific configuration files for add-on application software packages must
be installed within the directory /etc/opt/<subdir>, where <subdir> is the name
of the subtree in /opt where the static data from that package is stored.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Requirements
 
No structure is imposed on the internal arrangement of /etc/opt/<subdir>.
 
If a configuration file must reside in a different location in order for the
package or system to function properly, it may be placed in a location other
than /etc/opt/<subdir>.
 
    Rationale: Refer to the rationale for /opt.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/etc/X11 : Configuration for the X Window System (optional)
 
Purpose
 
/etc/X11 is the location for all X11 host-specific configuration. This
directory is necessary to allow local control if /usr is mounted read only.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Specific Options
 
The following files, or symbolic links to files, must be in /etc/X11 if the
corresponding subsystem is installed:
 
  File                              Description
Xconfig    The configuration file for early versions of XFree86 (optional)
XF86Config The configuration file for XFree86 versions 3 and 4 (optional)
Xmodmap    Global X11 keyboard modification file (optional)
 
Subdirectories of /etc/X11 may include those for xdm and for any other programs
(some window managers, for example) that need them. [8] We recommend that
window managers with only one configuration file which is a default .*wmrc file
must name it system.*wmrc (unless there is a widely-accepted alternative name)
and not use a subdirectory. Any window manager subdirectories must be
identically named to the actual window manager binary.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/etc/sgml : Configuration files for SGML (optional)
 
Purpose
 
Generic configuration files defining high-level parameters of the SGML systems
are installed here. Files with names *.conf indicate generic configuration
files. File with names *.cat are the DTD-specific centralized catalogs,
containing references to all other catalogs needed to use the given DTD. The
super catalog file catalog references all the centralized catalogs.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/etc/xml : Configuration files for XML (optional)
 
Purpose
 
Generic configuration files defining high-level parameters of the XML systems
are installed here. Files with names *.conf indicate generic configuration
files. The super catalog file catalog references all the centralized catalogs.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/home : User home directories (optional)
 
Purpose
 
/home is a fairly standard concept, but it is clearly a site-specific
filesystem. [9] The setup will differ from host to host. Therefore, no program
should rely on this location. [10]
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Requirements
 
User specific configuration files for applications are stored in the user's
home directory in a file that starts with the '.' character (a "dot file"). If
an application needs to create more than one dot file then they should be
placed in a subdirectory with a name starting with a '.' character, (a "dot
directory"). In this case the configuration files should not start with the '.'
character. [11]
 
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/lib : Essential shared libraries and kernel modules
 
Purpose
 
The /lib directory contains those shared library images needed to boot the
system and run the commands in the root filesystem, ie. by binaries in /bin and
/sbin. [12]
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Requirements
 
At least one of each of the following filename patterns are required (they may
be files, or symbolic links):
 
  File                    Description
libc.so.* The dynamically-linked C library (optional)
ld*      The execution time linker/loader (optional)
 
If a C preprocessor is installed, /lib/cpp must be a reference to it, for
historical reasons. [13]
 
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Specific Options
 
The following directories, or symbolic links to directories, must be in /lib,
if the corresponding subsystem is installed:
 
Directory            Description
modules  Loadable kernel modules (optional)
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/lib<qual> : Alternate format essential shared libraries (optional)
 
Purpose
 
There may be one or more variants of the /lib directory on systems which
support more than one binary format requiring separate libraries. [14]
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Requirements
 
If one or more of these directories exist, the requirements for their contents
are the same as the normal /lib directory, except that /lib<qual>/cpp is not
required. [15]
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/media : Mount point for removeable media
 
Purpose
 
This directory contains subdirectories which are used as mount points for
removeable media such as floppy disks, cdroms and zip disks.
 
    Rationale: Historically there have been a number of other different places
    used to mount removeable media such as /cdrom, /mnt or /mnt/cdrom. Placing
    the mount points for all removeable media directly in the root directory
    would potentially result in a large number of extra directories in /.
    Although the use of subdirectories in /mnt as a mount point has recently
    been common, it conflicts with a much older tradition of using /mnt
    directly as a temporary mount point.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Specific Options
 
The following directories, or symbolic links to directories, must be in /media,
if the corresponding subsystem is installed:
 
Directory        Description
floppy    Floppy drive (optional)
cdrom      CD-ROM drive (optional)
cdrecorder CD writer (optional)
zip        Zip drive (optional)
 
On systems where more than one device exists for mounting a certain type of
media, mount directories can be created by appending a digit to the name of
those available above starting with '0', but the unqualified name must also
exist. [16]
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/mnt : Mount point for a temporarily mounted filesystem
 
Purpose
 
This directory is provided so that the system administrator may temporarily
mount a filesystem as needed. The content of this directory is a local issue
and should not affect the manner in which any program is run.
 
This directory must not be used by installation programs: a suitable temporary
directory not in use by the system must be used instead.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/opt : Add-on application software packages
 
Purpose
 
/opt is reserved for the installation of add-on application software packages.
 
A package to be installed in /opt must locate its static files in a separate /
opt/<package> or /opt/<provider> directory tree, where <package> is a name that
describes the software package and <provider> is the provider's LANANA
registered name.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Requirements
 
Directory            Description
<package>  Static package objects
<provider> LANANA registered provider name
 
The directories /opt/bin, /opt/doc, /opt/include, /opt/info, /opt/lib, and /opt
/man are reserved for local system administrator use. Packages may provide
"front-end" files intended to be placed in (by linking or copying) these
reserved directories by the local system administrator, but must function
normally in the absence of these reserved directories.
 
Programs to be invoked by users must be located in the directory /opt/<package>
/bin or under the /opt/<provider> hierarchy. If the package includes UNIX
manual pages, they must be located in /opt/<package>/share/man or under the /
opt/<provider> hierarchy, and the same substructure as /usr/share/man must be
used.
 
Package files that are variable (change in normal operation) must be installed
in /var/opt. See the section on /var/opt for more information.
 
Host-specific configuration files must be installed in /etc/opt. See the
section on /etc for more information.
 
No other package files may exist outside the /opt, /var/opt, and /etc/opt
hierarchies except for those package files that must reside in specific
locations within the filesystem tree in order to function properly. For
example, device lock files must be placed in /var/lock and devices must be
located in /dev.
 
Distributions may install software in /opt, but must not modify or delete
software installed by the local system administrator without the assent of the
local system administrator.
 
    Rationale: The use of /opt for add-on software is a well-established
    practice in the UNIX community. The System V Application Binary Interface
    [AT&T 1990], based on the System V Interface Definition (Third Edition),
    provides for an /opt structure very similar to the one defined here.
 
    The Intel Binary Compatibility Standard v. 2 (iBCS2) also provides a
    similar structure for /opt.
 
    Generally, all data required to support a package on a system must be
    present within /opt/<package>, including files intended to be copied into /
    etc/opt/<package> and /var/opt/<package> as well as reserved directories in
    /opt.
 
    The minor restrictions on distributions using /opt are necessary because
    conflicts are possible between distribution-installed and locally-installed
    software, especially in the case of fixed pathnames found in some binary
    software.
 
    The structure of the directories below /opt/<provider> is left up to the
    packager of the software, though it is recommended that packages are
    installed in /opt/<provider>/<package> and follow a similar structure to
    the guidelines for /opt/package. A valid reason for diverging from this
    structure is for support packages which may have files installed in /opt/
    <provider>/lib or /opt/<provider>/bin.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/root : Home directory for the root user (optional)
 
Purpose
 
The root account's home directory may be determined by developer or local
preference, but this is the recommended default location. [17]
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/sbin : System binaries
 
Purpose
 
Utilities used for system administration (and other root-only commands) are
stored in /sbin, /usr/sbin, and /usr/local/sbin. /sbin contains binaries
essential for booting, restoring, recovering, and/or repairing the system in
addition to the binaries in /bin. [18] Programs executed after /usr is known to
be mounted (when there are no problems) are generally placed into /usr/sbin.
Locally-installed system administration programs should be placed into /usr/
local/sbin. [19]
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Requirements
 
The following commands, or symbolic links to commands, are required in /sbin.
 
Command            Description
shutdown Command to bring the system down.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Specific Options
 
The following files, or symbolic links to files, must be in /sbin if the
corresponding subsystem is installed:
 
Command                              Description
fastboot Reboot the system without checking the disks (optional)
fasthalt Stop the system without checking the disks (optional)
fdisk    Partition table manipulator (optional)
fsck    File system check and repair utility (optional)
fsck.*  File system check and repair utility for a specific filesystem
        (optional)
getty    The getty program (optional)
halt    Command to stop the system (optional)
ifconfig Configure a network interface (optional)
init    Initial process (optional)
mkfs    Command to build a filesystem (optional)
mkfs.*  Command to build a specific filesystem (optional)
mkswap  Command to set up a swap area (optional)
reboot  Command to reboot the system (optional)
route    IP routing table utility (optional)
swapon  Enable paging and swapping (optional)
swapoff  Disable paging and swapping (optional)
update  Daemon to periodically flush filesystem buffers (optional)
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/srv : Data for services provided by this system
 
Purpose
 
/srv contains site-specific data which is served by this system.
 
 
    Rationale: This main purpose of specifying this is so that users may find
    the location of the data files for particular service, and so that services
    which require a single tree for readonly data, writable data and scripts
    (such as cgi scripts) can be reasonably placed. Data that is only of
    interest to a specific user should go in that users' home directory.
 
    The methodology used to name subdirectories of /srv is unspecified as there
    is currently no consensus on how this should be done. One method for
    structuring data under /srv is by protocol, eg. ftp, rsync, www, and cvs.
    On large systems it can be useful to structure /srv by administrative
    context, such as /srv/physics/www, /srv/compsci/cvs, etc. This setup will
    differ from host to host. Therefore, no program should rely on a specific
    subdirectory structure of /srv existing or data necessarily being stored in
    /srv. However /srv should always exist on FHS compliant systems and should
    be used as the default location for such data.
 
    Distributions must take care not to remove locally placed files in these
    directories without administrator permission. [20]
 
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/tmp : Temporary files
 
Purpose
 
The /tmp directory must be made available for programs that require temporary
files.
 
Programs must not assume that any files or directories in /tmp are preserved
between invocations of the program.
 
    Rationale: IEEE standard P1003.2 (POSIX, part 2) makes requirements that
    are similar to the above section.
 
    Although data stored in /tmp may be deleted in a site-specific manner, it
    is recommended that files and directories located in /tmp be deleted
    whenever the system is booted.
 
    FHS added this recommendation on the basis of historical precedent and
    common practice, but did not make it a requirement because system
    administration is not within the scope of this standard.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Chapter 4. The /usr Hierarchy
 
Purpose
 
/usr is the second major section of the filesystem. /usr is shareable,
read-only data. That means that /usr should be shareable between various
FHS-compliant hosts and must not be written to. Any information that is
host-specific or varies with time is stored elsewhere.
 
Large software packages must not use a direct subdirectory under the /usr
hierarchy.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Requirements
 
The following directories, or symbolic links to directories, are required in /
usr.
 
Directory                  Description
bin      Most user commands
include  Header files included by C programs
lib      Libraries
local    Local hierarchy (empty after main installation)
sbin      Non-vital system binaries
share    Architecture-independent data
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Specific Options
 
Directory                  Description
X11R6    XWindow System, version 11 release 6 (optional)
games    Games and educational binaries (optional)
lib<qual> Alternate Format Libraries (optional)
src      Source code (optional)
 
An exception is made for the X Window System because of considerable precedent
and widely-accepted practice.
 
The following symbolic links to directories may be present. This possibility is
based on the need to preserve compatibility with older systems until all
implementations can be assumed to use the /var hierarchy.
 
    /usr/spool -> /var/spool
    /usr/tmp -> /var/tmp
    /usr/spool/locks -> /var/lock
 
Once a system no longer requires any one of the above symbolic links, the link
may be removed, if desired.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/usr/X11R6 : X Window System, Version 11 Release 6 (optional)
 
Purpose
 
This hierarchy is reserved for the X Window System, version 11 release 6, and
related files.
 
To simplify matters and make XFree86 more compatible with the X Window System
on other systems, the following symbolic links must be present if /usr/X11R6
exists:
 
    /usr/bin/X11 -> /usr/X11R6/bin
    /usr/lib/X11 -> /usr/X11R6/lib/X11
    /usr/include/X11 -> /usr/X11R6/include/X11
 
In general, software must not be installed or managed via the above symbolic
links. They are intended for utilization by users only. The difficulty is
related to the release version of the X Window System — in transitional
periods, it is impossible to know what release of X11 is in use.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Specific Options
 
Host-specific data in /usr/X11R6/lib/X11 should be interpreted as a
demonstration file. Applications requiring information about the current host
must reference a configuration file in /etc/X11, which may be linked to a file
in /usr/X11R6/lib. [21]
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/usr/bin : Most user commands
 
Purpose
 
This is the primary directory of executable commands on the system.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Specific Options
 
The following directories, or symbolic links to directories, must be in /usr/
bin, if the corresponding subsystem is installed:
 
Directory                    Description
mh        Commands for the MH mail handling system (optional)
 
/usr/bin/X11 must be a symlink to /usr/X11R6/bin if the latter exists.
 
The following files, or symbolic links to files, must be in /usr/bin, if the
corresponding subsystem is installed:
 
Command                      Description
perl    The Practical Extraction and Report Language (optional)
python  The Python interpreted language (optional)
tclsh  Simple shell containing Tcl interpreter (optional)
wish    Simple Tcl/Tk windowing shell (optional)
expect  Program for interactive dialog (optional)
 
    Rationale: Because shell script interpreters (invoked with #!<path> on the
    first line of a shell script) cannot rely on a path, it is advantageous to
    standardize their locations. The Bourne shell and C-shell interpreters are
    already fixed in /bin, but Perl, Python, and Tcl are often found in many
    different places. They may be symlinks to the physical location of the
    shell interpreters.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/usr/include : Directory for standard include files.
 
Purpose
 
This is where all of the system's general-use include files for the C
programming language should be placed.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Specific Options
 
The following directories, or symbolic links to directories, must be in /usr/
include, if the corresponding subsystem is installed:
 
Directory                Description
bsd      BSD compatibility include files (optional)
 
The symbolic link /usr/include/X11 must link to /usr/X11R6/include/X11 if the
latter exists.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/usr/lib : Libraries for programming and packages
 
Purpose
 
/usr/lib includes object files, libraries, and internal binaries that are not
intended to be executed directly by users or shell scripts. [22]
 
Applications may use a single subdirectory under /usr/lib. If an application
uses a subdirectory, all architecture-dependent data exclusively used by the
application must be placed within that subdirectory. [23]
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Specific Options
 
For historical reasons, /usr/lib/sendmail must be a symbolic link to /usr/sbin/
sendmail if the latter exists. [24]
 
If /lib/X11 exists, /usr/lib/X11 must be a symbolic link to /lib/X11, or to
whatever /lib/X11 is a symbolic link to. [25]
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/usr/lib<qual> : Alternate format libraries (optional)
 
Purpose
 
/usr/lib<qual> performs the same role as /usr/lib for an alternate binary
format, except that the symbolic links /usr/lib<qual>/sendmail and /usr/lib
<qual>/X11 are not required. [26]
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/usr/local : Local hierarchy
 
Purpose
 
The /usr/local hierarchy is for use by the system administrator when installing
software locally. It needs to be safe from being overwritten when the system
software is updated. It may be used for programs and data that are shareable
amongst a group of hosts, but not found in /usr.
 
Locally installed software must be placed within /usr/local rather than /usr
unless it is being installed to replace or upgrade software in /usr. [27]
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Requirements
 
The following directories, or symbolic links to directories, must be in /usr/
local
 
Directory                      Description
bin      Local binaries
etc      Host-specific system configuration for local binaries
games    Local game binaries
include  Local C header files
lib      Local libraries
man      Local online manuals
sbin      Local system binaries
share    Local architecture-independent hierarchy
src      Local source code
 
No other directories, except those listed below, may be in /usr/local after
first installing a FHS-compliant system.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Specific Options
 
If directories /lib<qual> or /usr/lib<qual> exist, the equivalent directories
must also exist in /usr/local.
 
/usr/local/etc may be a symbolic link to /etc/local.
 
    Rationale: The consistency of /usr/local/etc is beneficial to installers,
    and is already used in other systems. As all of /usr/local needs to be
    backed up to reproduce a system, it introduces no additional maintenance
    overhead, but a symlink to /etc/local is suitable if systems want alltheir
    configuration under one hierarchy.
 
    Note that /usr/etc is still not allowed: programs in /usr should place
    configuration files in /etc.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/usr/local/share
 
The requirements for the contents of this directory are the same as /usr/share.
The only additional constraint is that /usr/local/share/man and /usr/local/man
directories must be synonomous (usually this means that one of them must be a
symbolic link). [28]
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/usr/sbin : Non-essential standard system binaries
 
Purpose
 
This directory contains any non-essential binaries used exclusively by the
system administrator. System administration programs that are required for
system repair, system recovery, mounting /usr, or other essential functions
must be placed in /sbin instead. [29]
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/usr/share : Architecture-independent data
 
Purpose
 
The /usr/share hierarchy is for all read-only architecture independent data
files. [30]
 
This hierarchy is intended to be shareable among all architecture platforms of
a given OS; thus, for example, a site with i386, Alpha, and PPC platforms might
maintain a single /usr/share directory that is centrally-mounted. Note,
however, that /usr/share is generally not intended to be shared by different
OSes or by different releases of the same OS.
 
Any program or package which contains or requires data that doesn't need to be
modified should store that data in /usr/share (or /usr/local/share, if
installed locally). It is recommended that a subdirectory be used in /usr/share
for this purpose.
 
Game data stored in /usr/share/games must be purely static data. Any modifiable
files, such as score files, game play logs, and so forth, should be placed in /
var/games.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Requirements
 
The following directories, or symbolic links to directories, must be in /usr/
share
 
Directory                Description
man      Online manuals
misc      Miscellaneous architecture-independent data
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Specific Options
 
The following directories, or symbolic links to directories, must be in /usr/
share, if the corresponding subsystem is installed:
 
Directory                      Description
dict      Word lists (optional)
doc      Miscellaneous documentation (optional)
games    Static data files for /usr/games (optional)
info      GNU Info system s primary directory (optional)
locale    Locale information (optional)
nls      Message catalogs for Native language support (optional)
sgml      SGML data (optional)
terminfo  Directories for terminfo database (optional)
tmac      troff macros not distributed with groff (optional)
xml      XML data (optional)
zoneinfo  Timezone information and configuration (optional)
 
It is recommended that application-specific, architecture-independent
directories be placed here. Such directories include groff, perl, ghostscript,
texmf, and kbd (Linux) or syscons (BSD). They may, however, be placed in /usr/
lib for backwards compatibility, at the distributor's discretion. Similarly, a
/usr/lib/games hierarchy may be used in addition to the /usr/share/games
hierarchy if the distributor wishes to place some game data there.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/usr/share/dict : Word lists (optional)
 
Purpose
 
This directory is the home for word lists on the system; Traditionally this
directory contains only the English words file, which is used by look(1) and
various spelling programs. words may use either American or British spelling.
 
    Rationale: The reason that only word lists are located here is that they
    are the only files common to all spell checkers.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Specific Options
 
The following files, or symbolic links to files, must be in /usr/share/dict, if
the corresponding subsystem is installed:
 
File            Description
words List of English words (optional)
 
Sites that require both American and British spelling may link words to ­/usr/
share/dict/american-english or ­/usr/share/dict/british-english.
 
Word lists for other languages may be added using the English name for that
language, e.g., /usr/share/dict/french, /usr/share/dict/danish, etc. These
should, if possible, use an ISO 8859 character set which is appropriate for the
language in question; if possible the Latin1 (ISO 8859-1) character set should
be used (this is often not possible).
 
Other word lists must be included here, if present.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/usr/share/man : Manual pages
 
Purpose
 
This section details the organization for manual pages throughout the system,
including /usr/share/man. Also refer to the section on /var/cache/man.
 
The primary <mandir> of the system is /usr/share/man. /usr/share/man contains
manual information for commands and data under the / and /usr filesystems. [31]
 
Manual pages are stored in <mandir>/<locale>/man<section>/<arch>. An
explanation of <mandir>, <locale>, <section>, and <arch> is given below.
 
A description of each section follows:
 
  • man1: User programs Manual pages that describe publicly accessible commands
    are contained in this chapter. Most program documentation that a user will
    need to use is located here.
 
  • man2: System calls This section describes all of the system calls (requests
    for the kernel to perform operations).
 
  • man3: Library functions and subroutines Section 3 describes program library
    routines that are not direct calls to kernel services. This and chapter 2
    are only really of interest to programmers.
 
  • man4: Special files Section 4 describes the special files, related driver
    functions, and networking support available in the system. Typically, this
    includes the device files found in /dev and the kernel interface to
    networking protocol support.
 
  • man5: File formats The formats for many data files are documented in the
    section 5. This includes various include files, program output files, and
    system files.
 
  • man6: Games This chapter documents games, demos, and generally trivial
    programs. Different people have various notions about how essential this
    is.
 
  • man7: Miscellaneous Manual pages that are difficult to classify are
    designated as being section 7. The troff and other text processing macro
    packages are found here.
 
  • man8: System administration Programs used by system administrators for
    system operation and maintenance are documented here. Some of these
    programs are also occasionally useful for normal users.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Specific Options
 
The following directories, or symbolic links to directories, must be in /usr/
share/<mandir>/<locale>, unless they are empty: [32]
 
Directory          Description
man1      User programs (optional)
man2      System calls (optional)
man3      Library calls (optional)
man4      Special files (optional)
man5      File formats (optional)
man6      Games (optional)
man7      Miscellaneous (optional)
man8      System administration (optional)
 
The component <section> describes the manual section.
 
Provisions must be made in the structure of /usr/share/man to support manual
pages which are written in different (or multiple) languages. These provisions
must take into account the storage and reference of these manual pages.
Relevant factors include language (including geographical-based differences),
and character code set.
 
This naming of language subdirectories of /usr/share/man is based on Appendix E
of the POSIX 1003.1 standard which describes the locale identification string —
the most well-accepted method to describe a cultural environment. The <locale>
string is:
 
<language>[_<territory>][.<character-set>][,<version>]
 
The <language> field must be taken from ISO 639 (a code for the representation
of names of languages). It must be two characters wide and specified with
lowercase letters only.
 
The <territory> field must be the two-letter code of ISO 3166 (a specification
of representations of countries), if possible. (Most people are familiar with
the two-letter codes used for the country codes in email addresses.) It must be
two characters wide and specified with uppercase letters only. [33]
 
The <character-set> field must represent the standard describing the character
set. If the ­<character-set> field is just a numeric specification, the number
represents the number of the international standard describing the character
set. It is recommended that this be a numeric representation if possible (ISO
standards, especially), not include additional punctuation symbols, and that
any letters be in lowercase.
 
A parameter specifying a <version> of the profile may be placed after the ­
<character-set> field, delimited by a comma. This may be used to discriminate
between different cultural needs; for instance, dictionary order versus a more
systems-oriented collating order. This standard recommends not using the
<version> field, unless it is necessary.
 
Systems which use a unique language and code set for all manual pages may omit
the <locale> substring and store all manual pages in <mandir>. For example,
systems which only have English manual pages coded with ASCII, may store manual
pages (the man<section> directories) directly in /usr/share/man. (That is the
traditional circumstance and arrangement, in fact.)
 
Countries for which there is a well-accepted standard character code set may
omit the ­<character-set> field, but it is strongly recommended that it be
included, especially for countries with several competing standards.
 
Various examples:
 
Language Territory      Character Set  Directory
English  —              ASCII          /usr/share/man/en
English  United Kingdom ISO 8859-15    /usr/share/man/en_GB
English  United States  ASCII          /usr/share/man/en_US
French  Canada        ISO 8859-1      /usr/share/man/fr_CA
French  France        ISO 8859-1      /usr/share/man/fr_FR
German  Germany        ISO 646        /usr/share/man/de_DE.646
German  Germany        ISO 6937        /usr/share/man/de_DE.6937
German  Germany        ISO 8859-1      /usr/share/man/de_DE.88591
German  Switzerland    ISO 646        /usr/share/man/de_CH.646
Japanese Japan          JIS            /usr/share/man/ja_JP.jis
Japanese Japan          SJIS            /usr/share/man/ja_JP.sjis
Japanese Japan          UJIS (or EUC-J) /usr/share/man/ja_JP.ujis
 
Similarly, provision must be made for manual pages which are
architecture-dependent, such as documentation on device-drivers or low-level
system administration commands. These must be placed under an <arch> directory
in the appropriate man<section> directory; for example, a man page for the i386
ctrlaltdel(8) command might be placed in /usr/share/man/<locale>/man8/i386/
ctrlaltdel.8.
 
Manual pages for commands and data under /usr/local are stored in /usr/local/
man. Manual pages for X11R6 are stored in /usr/X11R6/man. It follows that all
manual page hierarchies in the system must have the same structure as /usr/
share/man.
 
The cat page sections (cat<section>) containing formatted manual page entries
are also found within subdirectories of <mandir>/<locale>, but are not required
nor may they be distributed in lieu of nroff source manual pages.
 
The numbered sections "1" through "8" are traditionally defined. In general,
the file name for manual pages located within a particular section end with .
<section>.
 
In addition, some large sets of application-specific manual pages have an
additional suffix appended to the manual page filename. For example, the MH
mail handling system manual pages must have mh appended to all MH manuals. All
X Window System manual pages must have an x appended to the filename.
 
The practice of placing various language manual pages in appropriate
subdirectories of /usr/share/man also applies to the other manual page
hierarchies, such as /usr/local/man and /usr/X11R6/man. (This portion of the
standard also applies later in the section on the optional /var/cache/man
structure.)
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/usr/share/misc : Miscellaneous architecture-independent data
 
This directory contains miscellaneous architecture-independent files which
don't require a separate subdirectory under /usr/share.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Specific Options
 
The following files, or symbolic links to files, must be in /usr/share/misc, if
the corresponding subsystem is installed:
 
  File                            Description
ascii      ASCII character set table (optional)
magic      Default list of magic numbers for the file command (optional)
termcap    Terminal capability database (optional)
termcap.db Terminal capability database (optional)
 
Other (application-specific) files may appear here, but a distributor may place
them in /usr/lib at their discretion. [34]
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/usr/share/sgml : SGML data (optional)
 
Purpose
 
/usr/share/sgml contains architecture-independent files used by SGML
applications, such as ordinary catalogs (not the centralized ones, see /etc/
sgml), DTDs, entities, or style sheets.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Specific Options
 
The following directories, or symbolic links to directories, must be in /usr/
share/sgml, if the corresponding subsystem is installed:
 
Directory      Description
docbook  docbook DTD (optional)
tei      tei DTD (optional)
html      html DTD (optional)
mathml    mathml DTD (optional)
 
Other files that are not specific to a given DTD may reside in their own
subdirectory.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/usr/share/xml : XML data (optional)
 
Purpose
 
/usr/share/xml contains architecture-independent files used by XML
applications, such as ordinary catalogs (not the centralized ones, see /etc/
sgml), DTDs, entities, or style sheets.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Specific Options
 
The following directories, or symbolic links to directories, must be in /usr/
share/xml, if the corresponding subsystem is installed:
 
Directory        Description
docbook  docbook XML DTD (optional)
xhtml    XHTML DTD (optional)
mathml    MathML DTD (optional)
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/usr/src : Source code (optional)
 
Purpose
 
Source code may be place placed in this subdirectory, only for reference
purposes. [35]
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Chapter 5. The /var Hierarchy
 
Purpose
 
/var contains variable data files. This includes spool directories and files,
administrative and logging data, and transient and temporary files.
 
Some portions of /var are not shareable between different systems. For
instance, /var/log, /var/lock, and /var/run. Other portions may be shared,
notably /var/mail, /var/cache/man, /var/cache/fonts, and /var/spool/news.
 
/var is specified here in order to make it possible to mount /usr read-only.
Everything that once went into /usr that is written to during system operation
(as opposed to installation and software maintenance) must be in /var.
 
If /var cannot be made a separate partition, it is often preferable to move /
var out of the root partition and into the /usr partition. (This is sometimes
done to reduce the size of the root partition or when space runs low in the
root partition.) However, /var must not be linked to /usr because this makes
separation of /usr and /var more difficult and is likely to create a naming
conflict. Instead, link /var to /usr/var.
 
Applications must generally not add directories to the top level of /var. Such
directories should only be added if they have some system-wide implication, and
in consultation with the FHS mailing list.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Requirements
 
The following directories, or symbolic links to directories, are required in /
var.
 
Directory                  Description
cache    Application cache data
lib      Variable state information
local    Variable data for /usr/local
lock      Lock files
log      Log files and directories
opt      Variable data for /opt
run      Data relevant to running processes
spool    Application spool data
tmp      Temporary files preserved between system reboots
 
Several directories are `reserved' in the sense that they must not be used
arbitrarily by some new application, since they would conflict with historical
and/or local practice. They are:
 
    /var/backups
     /var/cron
     /var/cron
     /var/msgs
     /var/msgs
     /var/preserve</PRE
     /var/preserve
></TD
 
></TR
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
></TABLE
 
></DIV
Specific Options
><DIV
 
CLASS="SECTION"
The following directories, or symbolic links to directories, must be in /var,
><HR><H2
if the corresponding subsystem is installed:
CLASS="SECTION"
 
><A
Directory                        Description
NAME="SPECIFICOPTIONS20"
account  Process accounting logs (optional)
>Specific Options</A
crash    System crash dumps (optional)
></H2
games    Variable game data (optional)
><P
mail      User mailbox files (optional)
>The following directories, or symbolic links to directories,
yp        Network Information Service (NIS) database files (optional)
must be in <TT
 
CLASS="FILENAME"
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
>/var</TT
 
>, if the corresponding subsystem
/var/account : Process accounting logs (optional)
is installed:</P
 
><DIV
Purpose
CLASS="INFORMALTABLE"
 
><P
This directory holds the current active process accounting log and the
></P
composite process usage data (as used in some UNIX-like systems by lastcomm and
><A
sa).
NAME="AEN2129"
 
></A
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
><TABLE
 
BORDER="0"
/var/cache : Application cache data
FRAME="void"
 
CLASS="CALSTABLE"
Purpose
><COL><COL><THEAD
 
><TR
/var/cache is intended for cached data from applications. Such data is locally
><TH
generated as a result of time-consuming I/O or calculation. The application
>Directory</TH
must be able to regenerate or restore the data. Unlike /var/spool, the cached
><TH
files can be deleted without data loss. The data must remain valid between
>Description</TH
invocations of the application and rebooting the system.
></TR
 
></THEAD
Files located under /var/cache may be expired in an application specific
><TBODY
manner, by the system administrator, or both. The application must always be
><TR
able to recover from manual deletion of these files (generally because of a
><TD
disk space shortage). No other requirements are made on the data format of the
><TT
cache directories.
CLASS="FILENAME"
 
>account</TT
    Rationale: The existence of a separate directory for cached data allows
></TD
    system administrators to set different disk and backup policies from other
><TD
    directories in /var.
>Process accounting logs (optional)</TD
 
></TR
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
><TR
 
><TD
Specific Options
><TT
 
CLASS="FILENAME"
Directory                Description
>crash</TT
fonts    Locally-generated fonts (optional)
></TD
man      Locally-formatted manual pages (optional)
><TD
www      WWW proxy or cache data (optional)
>System crash dumps (optional)</TD
<package> Package specific cache data (optional)
></TR
 
><TR
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
><TD
 
><TT
/var/cache/fonts : Locally-generated fonts (optional)
CLASS="FILENAME"
 
>games</TT
Purpose
></TD
 
><TD
The directory /var/cache/fonts should be used to store any dynamically-created
>Variable game data (optional)</TD
fonts. In particular, all of the fonts which are automatically generated by
></TR
mktexpk must be located in appropriately-named subdirectories of /var/cache/
><TR
fonts. [36]
><TD
 
><TT
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
CLASS="FILENAME"
 
>mail</TT
Specific Options
></TD
 
><TD
Other dynamically created fonts may also be placed in this tree, under
>User mailbox files (optional)</TD
appropriately-named subdirectories of /var/cache/fonts.
></TR
 
><TR
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
><TD
 
><TT
/var/cache/man : Locally-formatted manual pages (optional)
CLASS="FILENAME"
 
>yp</TT
Purpose
></TD
 
><TD
This directory provides a standard location for sites that provide a read-only
>Network Information Service (NIS) database files (optional)
/usr partition, but wish to allow caching of locally-formatted man pages. Sites
      </TD
that mount /usr as writable (e.g., single-user installations) may choose not to
></TR
use /var/cache/man and may write formatted man pages into the cat<section>
></TBODY
directories in /usr/share/man directly. We recommend that most sites use one of
></TABLE
the following options instead:
><P
 
></P
  • Preformat all manual pages alongside the unformatted versions.
></DIV
 
></DIV
  • Allow no caching of formatted man pages, and require formatting to be done
><DIV
    each time a man page is brought up.
CLASS="SECTION"
 
><HR><H2
  • Allow local caching of formatted man pages in /var/cache/man.
CLASS="SECTION"
 
><A
The structure of /var/cache/man needs to reflect both the fact of multiple man
NAME="VARACCOUNTPROCESSACCOUNTINGLOGS"
page hierarchies and the possibility of multiple language support.
>/var/account : Process accounting logs (optional)</A
 
></H2
Given an unformatted manual page that normally appears in <path>/man/<locale>/
><DIV
man<section>, the directory to place formatted man pages in is /var/cache/man/
CLASS="SECTION"
<catpath>/<locale>/cat<section>, where <catpath> is derived from <path> by
><H3
removing any leading usr and/or trailing share pathname components. (Note that
CLASS="SECTION"
the <locale> component may be missing.) [37]
><A
 
NAME="PURPOSE32"
Man pages written to /var/cache/man may eventually be transferred to the
>Purpose</A
appropriate preformatted directories in the source man hierarchy or expired;
></H3
likewise formatted man pages in the source man hierarchy may be expired if they
><P
are not accessed for a period of time.
>This directory holds the current active process accounting log
 
and the composite process usage data (as used in some UNIX-like
If preformatted manual pages come with a system on read-only media (a CD-ROM,
systems by <B
for instance), they must be installed in the source man hierarchy (e.g. /usr/
CLASS="COMMAND"
share/man/cat<section>). /var/cache/man is reserved as a writable cache for
>lastcomm</B
formatted manual pages.
> and
 
<B
    Rationale: Release 1.2 of the standard specified /var/catman for this
CLASS="COMMAND"
    hierarchy. The path has been moved under /var/cache to better reflect the
>sa</B
    dynamic nature of the formatted man pages. The directory name has been
>).</P
    changed to man to allow for enhancing the hierarchy to include
></DIV
    post-processed formats other than "cat", such as PostScript, HTML, or DVI.  
></DIV
 
><DIV
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
CLASS="SECTION"
 
><HR><H2
/var/crash : System crash dumps (optional)
CLASS="SECTION"
 
><A
Purpose
NAME="VARCACHEAPPLICATIONCACHEDATA"
 
>/var/cache : Application cache data</A
This directory holds system crash dumps. As of the date of this release of the
></H2
standard, system crash dumps were not supported under Linux but may be
><DIV
supported by other systems which may comply with the FHS.
CLASS="SECTION"
 
><H3
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
CLASS="SECTION"
 
><A
/var/games : Variable game data (optional)
NAME="PURPOSE33"
 
>Purpose</A
Purpose
></H3
 
><P
Any variable data relating to games in /usr should be placed here. /var/games
><TT
should hold the variable data previously found in /usr; static data, such as
CLASS="FILENAME"
help text, level descriptions, and so on, must remain elsewhere, such as /usr/
>/var/cache</TT
share/games.
> is intended for cached data from
 
applications.  Such data is locally generated as a result of
    Rationale: /var/games has been given a hierarchy of its own, rather than
time-consuming I/O or calculation. The application must be able to
    leaving it merged in with the old /var/lib as in release 1.2. The
regenerate or restore the data.  Unlike
    separation allows local control of backup strategies, permissions, and disk
<TT
    usage, as well as allowing inter-host sharing and reducing clutter in /var/
CLASS="FILENAME"
    lib. Additionally, /var/games is the path traditionally used by BSD.
>/var/spool</TT
 
>, the cached files can be deleted
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
without data loss. The data must remain valid between invocations of
 
the application and rebooting the system.</P
/var/lib : Variable state information
><P
 
>Files located under <TT
Purpose
CLASS="FILENAME"
 
>/var/cache</TT
This hierarchy holds state information pertaining to an application or the
> may be
system. State information is data that programs modify while they run, and that
expired in an application specific manner, by the system
pertains to one specific host. Users must never need to modify files in /var/
administrator, or both. The application must always be able to
lib to configure a package's operation.
recover from manual deletion of these files (generally because of a
 
disk space shortage).  No other requirements are made on the data
State information is generally used to preserve the condition of an application
format of the cache directories.</P
(or a group of inter-related applications) between invocations and between
><DIV
different instances of the same application. State information should generally
CLASS="TIP"
remain valid after a reboot, should not be logging output, and should not be
><P
spooled data.
></P
 
><TABLE
An application (or a group of inter-related applications) must use a
CLASS="TIP"
subdirectory of /var/lib for its data. There is one required subdirectory, /var
WIDTH="100%"
/lib/misc, which is intended for state files that don't need a subdirectory;
BORDER="0"
the other subdirectories should only be present if the application in question
><TR
is included in the distribution. [38]
><TD
 
WIDTH="25"
/var/lib/<name> is the location that must be used for all distribution
ALIGN="CENTER"
packaging support. Different distributions may use different names, of course.
VALIGN="TOP"
 
><IMG
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
SRC="tip.gif"
 
HSPACE="5"
Requirements
ALT="Tip"></TD
 
><TH
The following directories, or symbolic links to directories, are required in /
ALIGN="LEFT"
var/lib:
VALIGN="CENTER"
 
><B
Directory       Description
>Rationale</B
misc      Miscellaneous state data
></TH
 
></TR
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
><TR
 
><TD
Specific Options
>&nbsp;</TD
 
><TD
The following directories, or symbolic links to directories, must be in /var/
ALIGN="LEFT"
lib, if the corresponding subsystem is installed:
VALIGN="TOP"
 
><P
Directory                    Description
>The existence of a separate directory for cached data allows
<editor> Editor backup files and state (optional)
system administrators to set different disk and backup policies from
<pkgtool> Packaging support files (optional)
other directories in <TT
<package> State data for packages and subsystems (optional)
CLASS="FILENAME"
hwclock  State directory for hwclock (optional)
>/var</TT
xdm      X display manager variable data (optional)
>.&#13;</P
 
></TD
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
></TR
 
></TABLE
/var/lib/<editor> : Editor backup files and state (optional)
></DIV
 
></DIV
Purpose
><DIV
 
CLASS="SECTION"
These directories contain saved files generated by any unexpected termination
><HR><H3
of an editor (e.g., elvis, jove, nvi).
CLASS="SECTION"
 
><A
Other editors may not require a directory for crash-recovery files, but may
NAME="SPECIFICOPTIONS21"
require a well-defined place to store other information while the editor is
>Specific Options</A
running. This information should be stored in a subdirectory under /var/lib
></H3
(for example, GNU Emacs would place lock files in /var/lib/emacs/lock).
><DIV
 
CLASS="INFORMALTABLE"
Future editors may require additional state information beyond crash-recovery
><P
files and lock files — this information should also be placed under /var/lib/
></P
<editor>.
><A
 
NAME="AEN2178"
    Rationale: Previous Linux releases, as well as all commercial vendors, use
></A
    /var/preserve for vi or its clones. However, each editor uses its own
><TABLE
    format for these crash-recovery files, so a separate directory is needed
BORDER="0"
    for each editor.
FRAME="void"
 
CLASS="CALSTABLE"
    Editor-specific lock files are usually quite different from the device or
><COL><COL><THEAD
    resource lock files that are stored in /var/lock and, hence, are stored
><TR
    under /var/lib.
><TH
 
>Directory</TH
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
><TH
 
>Description</TH
/var/lib/hwclock : State directory for hwclock (optional)
></TR
 
></THEAD
Purpose
><TBODY
 
><TR
This directory contains the file /var/lib/hwclock/adjtime.
><TD
 
><TT
    Rationale: In FHS 2.1, this file was /etc/adjtime, but as hwclock updates
CLASS="FILENAME"
    it, that was obviously incorrect.
>fonts</TT
 
></TD
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
><TD
 
>Locally-generated fonts (optional)</TD
/var/lib/misc : Miscellaneous variable data
></TR
 
><TR
Purpose
><TD
 
><TT
This directory contains variable data not placed in a subdirectory in /var/lib.
CLASS="FILENAME"
An attempt should be made to use relatively unique names in this directory to
>man</TT
avoid namespace conflicts. [39]
></TD
 
><TD
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
>Locally-formatted manual pages (optional)</TD
 
></TR
/var/lock : Lock files
><TR
 
><TD
Purpose
><TT
 
CLASS="FILENAME"
Lock files should be stored within the /var/lock directory structure.
>www</TT
 
></TD
Lock files for devices and other resources shared by multiple applications,
><TD
such as the serial device lock files that were originally found in either /usr/
>WWW proxy or cache data (optional)</TD
spool/locks or /usr/spool/uucp, must now be stored in /var/lock. The naming
></TR
convention which must be used is "LCK.." followed by the base name of the
><TR
device. For example, to lock /dev/ttyS0 the file "LCK..ttyS0" would be created.
><TD
[40]
><TT
 
CLASS="FILENAME"
The format used for the contents of such lock files must be the HDB UUCP lock
>&lt;package&gt;</TT
file format. The HDB format is to store the process identifier (PID) as a ten
></TD
byte ASCII decimal number, with a trailing newline. For example, if process
><TD
1230 holds a lock file, it would contain the eleven characters: space, space,
>Package specific cache data (optional)</TD
space, space, space, space, one, two, three, zero, and newline.
></TR
 
></TBODY
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
></TABLE
 
><P
/var/log : Log files and directories
></P
 
></DIV
Purpose
></DIV
 
><DIV
This directory contains miscellaneous log files. Most logs must be written to
CLASS="SECTION"
this directory or an appropriate subdirectory.
><HR><H3
 
CLASS="SECTION"
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
><A
 
NAME="VARCACHEFONTSLOCALLYGENERATEDFONTS"
Specific Options
>/var/cache/fonts : Locally-generated fonts (optional)</A
 
></H3
The following files, or symbolic links to files, must be in /var/log, if the
><DIV
corresponding subsystem is installed:
CLASS="SECTION"
 
><H4
  File              Description
CLASS="SECTION"
lastlog  record of last login of each user
><A
messages system messages from syslogd
NAME="PURPOSE34"
wtmp    record of all logins and logouts
>Purpose</A
 
></H4
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
><P
 
>The directory <TT
/var/mail : User mailbox files (optional)
CLASS="FILENAME"
 
>/var/cache/fonts</TT
Purpose
> should be used to store any
 
dynamically-created fonts. In particular, all of the fonts which are
The mail spool must be accessible through /var/mail and the mail spool files
automatically generated by <B
must take the form <username>. [41]
CLASS="COMMAND"
 
>mktexpk</B
User mailbox files in this location must be stored in the standard UNIX mailbox
> must be located in
format.
appropriately-named subdirectories of <TT
 
CLASS="FILENAME"
    Rationale: The logical location for this directory was changed from /var/
>/var/cache/fonts</TT
    spool/mail in order to bring FHS in-line with nearly every UNIX
>.
    implementation. This change is important for inter-operability since a
    single /var/mail is often shared between multiple hosts and multiple UNIX
    implementations (despite NFS locking issues).
 
    It is important to note that there is no requirement to physically move the
    mail spool to this location. However, programs and header files must be
    changed to use /var/mail.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/var/opt : Variable data for /opt
 
Purpose
 
Variable data of the packages in /opt must be installed in /var/opt/<subdir>,
where <subdir> is the name of the subtree in /opt where the static data from an
add-on software package is stored, except where superseded by another file in /
etc. No structure is imposed on the internal arrangement of /var/opt/<subdir>.
 
    Rationale: Refer to the rationale for /opt.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/var/run : Run-time variable data
 
Purpose
 
This directory contains system information data describing the system since it
was booted. Files under this directory must be cleared (removed or truncated as
appropriate) at the beginning of the boot process. Programs may have a
subdirectory of /var/run; this is encouraged for programs that use more than
one run-time file. [42] Process identifier (PID) files, which were originally
placed in /etc, must be placed in /var/run. The naming convention for PID files
is <program-name>.pid. For example, the crond PID file is named /var/run/
crond.pid.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Requirements
 
The internal format of PID files remains unchanged. The file must consist of
the process identifier in ASCII-encoded decimal, followed by a newline
character. For example, if crond was process number 25, /var/run/crond.pid
would contain three characters: two, five, and newline.
 
Programs that read PID files should be somewhat flexible in what they accept;
i.e., they should ignore extra whitespace, leading zeroes, absence of the
trailing newline, or additional lines in the PID file. Programs that create PID
files should use the simple specification located in the above paragraph.
 
The utmp file, which stores information about who is currently using the
system, is located in this directory.
 
System programs that maintain transient UNIX-domain sockets must place them in
this directory.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/var/spool : Application spool data
 
Purpose
 
/var/spool contains data which is awaiting some kind of later processing. Data
in /var/spool represents work to be done in the future (by a program, user, or
administrator); often data is deleted after it has been processed. [43]
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Specific Options
 
The following directories, or symbolic links to directories, must be in /var/
spool, if the corresponding subsystem is installed:
 
Directory            Description
lpd      Printer spool directory (optional)
mqueue    Outgoing mail queue (optional)
news      News spool directory (optional)
rwho      Rwhod files (optional)
uucp      Spool directory for UUCP (optional)
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/var/spool/lpd : Line-printer daemon print queues (optional)
 
Purpose
 
The lock file for lpd, lpd.lock, must be placed in /var/spool/lpd. It is
suggested that the lock file for each printer be placed in the spool directory
for that specific printer and named lock.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Specific Options
 
Directory              Description
printer  Spools for a specific printer (optional)
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/var/spool/rwho : Rwhod files (optional)
 
Purpose
 
This directory holds the rwhod information for other systems on the local net.
 
    Rationale: Some BSD releases use /var/rwho for this data; given its
    historical location in /var/spool on other systems and its approximate fit
    to the definition of `spooled' data, this location was deemed more
    appropriate.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/var/tmp : Temporary files preserved between system reboots
 
Purpose
 
The /var/tmp directory is made available for programs that require temporary
files or directories that are preserved between system reboots. Therefore, data
stored in /var/tmp is more persistent than data in /tmp.
 
Files and directories located in /var/tmp must not be deleted when the system
is booted. Although data stored in /var/tmp is typically deleted in a
site-specific manner, it is recommended that deletions occur at a less frequent
interval than /tmp.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/var/yp : Network Information Service (NIS) database files (optional)
 
Purpose
 
Variable data for the Network Information Service (NIS), formerly known as the
Sun Yellow Pages (YP), must be placed in this directory.
 
    Rationale: /var/yp is the standard directory for NIS (YP) data and is
    almost exclusively used in NIS documentation and systems. [44]
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Chapter 6. Operating System Specific Annex
 
This section is for additional requirements and recommendations that only apply
to a specific operating system. The material in this section should never
conflict with the base standard.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Linux
 
This is the annex for the Linux operating system.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/ : Root directory
 
On Linux systems, if the kernel is located in /, we recommend using the names
vmlinux or vmlinuz, which have been used in recent Linux kernel source
packages.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/bin : Essential user command binaries (for use by all users)
 
Linux systems which require them place these additional files into /bin:
 
  • setserial
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/dev : Devices and special files
 
The following devices must exist under /dev.
 
/dev/null
 
    All data written to this device is discarded. A read from this device will
    return an EOF condition.
 
/dev/zero
 
    This device is a source of zeroed out data. All data written to this device
    is discarded. A read from this device will return as many bytes containing
    the value zero as was requested.
 
/dev/tty
 
    This device is a synonym for the controlling terminal of a process. Once
    this device is opened, all reads and writes will behave as if the actual
    controlling terminal device had been opened.
 
    Rationale: Previous versions of the FHS had stricter requirements for /dev.
    Other devices may also exist in /dev. Device names may exist as symbolic
    links to other device nodes located in /dev or subdirectories of /dev.
    There is no requirement concerning major/minor number values.
 
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/etc : Host-specific system configuration
 
Linux systems which require them place these additional files into /etc.
 
  • lilo.conf
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/lib64 and /lib32 : 64/32-bit libraries (architecture dependent)
 
The 64-bit architectures PPC64, s390x, sparc64 and AMD64 must place 64-bit
libraries in /lib64, and 32-bit (or 31-bit on s390) libraries in /lib.
 
The 64-bit architecture IA64 must place 64-bit libraries in /lib.
 
 
    Rationale: This is a refinement of the general rules for /lib<qual> and /
    usr/lib<qual>. The architectures PPC64, s390x, sparc64 and AMD64 support
    support both 32-bit (for s390 more precise 31-bit) and 64-bit programs.
    Using lib for 32-bit binaries allows existing binaries from the 32-bit
    systems to work without any changes: such binaries are expected to be
    numerous. IA-64 uses a different scheme, reflecting the deprecation of
    32-bit binaries (and hence libraries) on that architecture.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/proc : Kernel and process information virtual filesystem
 
The proc filesystem is the de-facto standard Linux method for handling process
and system information, rather than /dev/kmem and other similar methods. We
strongly encourage this for the storage and retrieval of process information as
well as other kernel and memory information.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/sbin : Essential system binaries
 
Linux systems place these additional files into /sbin.
 
  • Second extended filesystem commands (optional):
 
      □ badblocks
 
      □ dumpe2fs
 
      □ e2fsck
 
      □ mke2fs
 
      □ mklost+found
 
      □ tune2fs
 
  • Boot-loader map installer (optional):
 
      □ lilo
 
Optional files for /sbin:
 
  • Static binaries:
 
      □ ldconfig
 
      □ sln
 
      □ ssync
 
    Static ln (sln) and static sync (ssync) are useful when things go wrong.
    The primary use of sln (to repair incorrect symlinks in /lib after a poorly
    orchestrated upgrade) is no longer a major concern now that the ldconfig
    program (usually located in /usr/sbin) exists and can act as a guiding hand
    in upgrading the dynamic libraries. Static sync is useful in some emergency
    situations. Note that these need not be statically linked versions of the
    standard ln and sync, but may be.
 
    The ldconfig binary is optional for /sbin since a site may choose to run
    ldconfig at boot time, rather than only when upgrading the shared
    libraries. (It's not clear whether or not it is advantageous to run
    ldconfig on each boot.) Even so, some people like ldconfig around for the
    following (all too common) situation:
 
    1. I've just removed /lib/<file>.
 
    2. I can't find out the name of the library because ls is dynamically
        linked, I'm using a shell that doesn't have ls built-in, and I don't
        know about using "echo *" as a replacement.
 
    3. I have a static sln, but I don't know what to call the link.
 
  • Miscellaneous:
 
      □ ctrlaltdel
 
      □ kbdrate
 
    So as to cope with the fact that some keyboards come up with such a high
    repeat rate as to be unusable, kbdrate may be installed in /sbin on some
    systems.
 
    Since the default action in the kernel for the Ctrl-Alt-Del key combination
    is an instant hard reboot, it is generally advisable to disable the
    behavior before mounting the root filesystem in read-write mode. Some init
    suites are able to disable Ctrl-Alt-Del, but others may require the
    ctrlaltdel program, which may be installed in /sbin on those systems.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/usr/include : Header files included by C programs
 
These symbolic links are required if a C or C++ compiler is installed and only
for systems not based on glibc.
 
    /usr/include/asm -> /usr/src/linux/include/asm-<arch>
    /usr/include/linux -> /usr/src/linux/include/linux
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/usr/src : Source code
 
For systems based on glibc, there are no specific guidelines for this
directory. For systems based on Linux libc revisions prior to glibc, the
following guidelines and rationale apply:
 
The only source code that should be placed in a specific location is the Linux
kernel source code. It is located in /usr/src/linux.
 
If a C or C++ compiler is installed, but the complete Linux kernel source code
is not installed, then the include files from the kernel source code must be
located in these directories:
 
    /usr/src/linux/include/asm-<arch>
    /usr/src/linux/include/linux
 
<arch> is the name of the system architecture.
 
    Note: /usr/src/linux may be a symbolic link to a kernel source code tree.
 
    Rationale: It is important that the kernel include files be located in /usr
    /src/linux and not in /usr/include so there are no problems when system
    administrators upgrade their kernel version for the first time.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
/var/spool/cron : cron and at jobs
 
This directory contains the variable data for the cron and at programs.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Chapter 7. Appendix
 
The FHS mailing list
 
The FHS mailing list is located at
<freestandards-fhs-discuss@lists.sourceforge.net>. You can subscribe to the
mailing list at this page http://sourceforge.net/projects/freestandards/.
 
Thanks to Network Operations at the University of California at San Diego who
allowed us to use their excellent mailing list server.
 
As noted in the introduction, please do not send mail to the mailing list
without first contacting the FHS editor or a listed contributor.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Background of the FHS
 
The process of developing a standard filesystem hierarchy began in August 1993
with an effort to restructure the file and directory structure of Linux. The
FSSTND, a filesystem hierarchy standard specific to the Linux operating system,
was released on February 14, 1994. Subsequent revisions were released on
October 9, 1994 and March 28, 1995.
 
In early 1995, the goal of developing a more comprehensive version of FSSTND to
address not only Linux, but other UNIX-like systems was adopted with the help
of members of the BSD development community. As a result, a concerted effort
was made to focus on issues that were general to UNIX-like systems. In
recognition of this widening of scope, the name of the standard was changed to
Filesystem Hierarchy Standard or FHS for short.
 
Volunteers who have contributed extensively to this standard are listed at the
end of this document. This standard represents a consensus view of those and
other contributors.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
General Guidelines
 
Here are some of the guidelines that have been used in the development of this
standard:
 
  • Solve technical problems while limiting transitional difficulties.
 
  • Make the specification reasonably stable.
 
  • Gain the approval of distributors, developers, and other decision-makers in
    relevant development groups and encourage their participation.
 
  • Provide a standard that is attractive to the implementors of different
    UNIX-like systems.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Scope
 
This document specifies a standard filesystem hierarchy for FHS filesystems by
specifying the location of files and directories, and the contents of some
system files.
 
This standard has been designed to be used by system integrators, package
developers, and system administrators in the construction and maintenance of
FHS compliant filesystems. It is primarily intended to be a reference and is
not a tutorial on how to manage a conforming filesystem hierarchy.
 
The FHS grew out of earlier work on FSSTND, a filesystem organization standard
for the Linux operating system. It builds on FSSTND to address interoperability
issues not just in the Linux community but in a wider arena including
4.4BSD-based operating systems. It incorporates lessons learned in the BSD
world and elsewhere about multi-architecture support and the demands of
heterogeneous networking.
 
Although this standard is more comprehensive than previous attempts at
filesystem hierarchy standardization, periodic updates may become necessary as
requirements change in relation to emerging technology. It is also possible
that better solutions to the problems addressed here will be discovered so that
our solutions will no longer be the best possible solutions. Supplementary
drafts may be released in addition to periodic updates to this document.
However, a specific goal is backwards compatibility from one release of this
document to the next.
 
Comments related to this standard are welcome. Any comments or suggestions for
changes may be directed to the FHS editor (Daniel Quinlan
<quinlan@pathname.com>) or the FHS mailing list. Typographical or grammatical
comments should be directed to the FHS editor.
 
Before sending mail to the mailing list it is requested that you first contact
the FHS editor in order to avoid excessive re-discussion of old topics.
 
Questions about how to interpret items in this document may occasionally arise.
If you have need for a clarification, please contact the FHS editor. Since this
standard represents a consensus of many participants, it is important to make
certain that any interpretation also represents their collective opinion. For
this reason it may not be possible to provide an immediate response unless the
inquiry has been the subject of previous discussion.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Acknowledgments
 
The developers of the FHS wish to thank the developers, system administrators,
and users whose input was essential to this standard. We wish to thank each of
the contributors who helped to write, compile, and compose this standard.
 
The FHS Group also wishes to thank those Linux developers who supported the
FSSTND, the predecessor to this standard. If they hadn't demonstrated that the
FSSTND was beneficial, the FHS could never have evolved.
 
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 
Contributors
 
Brandon S. Allbery <bsa@kf8nh.wariat.org>
Keith Bostic      <bostic@cs.berkeley.edu>
Drew Eckhardt      <drew@colorado.edu>
Rik Faith          <faith@cs.unc.edu>
Stephen Harris    <sweh@spuddy.mew.co.uk>
Ian Jackson        <ijackson@cus.cam.ac.uk>
Andreas Jaeger    <aj@suse.de>
John A. Martin    <jmartin@acm.org>
Ian McCloghrie    <ian@ucsd.edu>
Chris Metcalf      <metcalf@lcs.mit.edu>
Ian Murdock        <imurdock@debian.org>
David C. Niemi    <niemidc@clark.net>
Daniel Quinlan    <quinlan@pathname.com>
Eric S. Raymond    <esr@thyrsus.com>
Rusty Russell      <rusty@rustcorp.com.au>
Mike Sangrey      <mike@sojurn.lns.pa.us>
David H. Silber    <dhs@glowworm.firefly.com>
Thomas Sippel-Dau  <t.sippel-dau@ic.ac.uk>
Theodore Ts'o      <tytso@athena.mit.edu>
Stephen Tweedie    <sct@dcs.ed.ac.uk>
Fred N. van Kempen <waltje@infomagic.com>
Bernd Warken      <bwarken@mayn.de>
Christopher Yeoh  <cyeoh@samba.org>
 
Notes
 
[1]  Command binaries that are not essential enough to place into /bin must be
    placed in /usr/bin, instead. Items that are required only by non-root
    users (the X Window System, chsh, etc.) are generally not essential enough
    to be placed into the root partition.
 
[2]  Programs necessary to arrange for the boot loader to be able to boot a
    file must be placed in /sbin. Configuration files for boot loaders must be
    placed in /etc.
 
    The GRUB bootloader reads its configurations file before booting, so that
    must be placed in /boot. However, it is a configuration file, so should be
    in /etc. The answer here is a symbolic link such as /etc/grub/menu.lst ->
    /boot/menu.lst.
 
[3]  On some i386 machines, it may be necessary for /boot to be located on a
    separate partition located completely below cylinder 1024 of the boot
    device due to hardware constraints.
 
    Certain MIPS systems require a /boot partition that is a mounted MS-DOS
    filesystem or whatever other filesystem type is accessible for the
    firmware. This may result in restrictions with respect to usable filenames
    within /boot (only for affected systems).
 
[4]  The setup of command scripts invoked at boot time may resemble System V,
    BSD or other models. Further specification in this area may be added to a
    future version of this standard.
 
[5]  It is recommended that files be stored in subdirectories of /etc rather
    than directly in /etc.
 
[6]  Systems that use the shadow password suite will have additional
    configuration files in /etc (/etc/shadow and others) and programs in /usr/
    sbin (useradd, usermod, and others).
 
[7]  On some Linux systems, this may be a symbolic link to /proc/mounts, in
    which case this exception is not required.
 
[8]  /etc/X11/xdm holds the configuration files for xdm. These are most of the
    files previously found in /usr/lib/X11/xdm. Some local variable data for
    xdm is stored in /var/lib/xdm.
 
[9]  Different people prefer to place user accounts in a variety of places.
    This section describes only a suggested placement for user home
    directories; nevertheless we recommend that all FHS-compliant
    distributions use this as the default location for home directories.
 
    On small systems, each user's directory is typically one of the many
    subdirectories of /home such as /home/smith, /home/torvalds, /home/
    operator, etc. On large systems (especially when the /home directories are
    shared amongst many hosts using NFS) it is useful to subdivide user home
    directories. Subdivision may be accomplished by using subdirectories such
    as /home/staff, /home/guests, /home/students, etc.
 
[10] If you want to find out a user's home directory, you should use the
    getpwent(3) library function rather than relying on /etc/passwd because
    user information may be stored remotely using systems such as NIS.
 
[11] It is recommended that apart from autosave and lock files programs should
    refrain from creating non dot files or directories in a home directory
    without user intervention.
 
[12] Shared libraries that are only necessary for binaries in /usr (such as any
    X Window binaries) must not be in /lib. Only the shared libraries required
    to run binaries in /bin and /sbin may be here. In particular, the library
    libm.so.* may also be placed in /usr/lib if it is not required by anything
    in /bin or /sbin.
 
[13] The usual placement of this binary is /usr/bin/cpp.
 
[14] This is commonly used for 64-bit or 32-bit support on systems which
    support multiple binary formats, but require libraries of the same name.
    In this case, /lib32 and /lib64 might be the library directories, and /lib
    a symlink to one of them.
 
[15] /lib<qual>/cpp is still permitted: this allows the case where /lib and /
    lib<qual> are the same (one is a symbolic link to the other).
 
[16] A compliant implementation with two CDROM drives might have /media/cdrom0
    and /media/cdrom1 with /media/cdrom a symlink to either of these.
 
[17] If the home directory of the root account is not stored on the root
    partition it will be necessary to make certain it will default to / if it
    can not be located.
 
    We recommend against using the root account for tasks that can be
    performed as an unprivileged user, and that it be used solely for system
    administration. For this reason, we recommend that subdirectories for mail
    and other applications not appear in the root account's home directory,
    and that mail for administration roles such as root, postmaster, and
    webmaster be forwarded to an appropriate user.
 
[18] Originally, /sbin binaries were kept in /etc.
 
[19] Deciding what things go into "sbin" directories is simple: if a normal
    (not a system administrator) user will ever run it directly, then it must
    be placed in one of the "bin" directories. Ordinary users should not have
    to place any of the sbin directories in their path.
 
    For example, files such as chfn which users only occasionally use must
    still be placed in /usr/bin. ping, although it is absolutely necessary for
    root (network recovery and diagnosis) is often used by users and must live
    in /bin for that reason.
 
    We recommend that users have read and execute permission for everything in
    /sbin except, perhaps, certain setuid and setgid programs. The division
    between /bin and /sbin was not created for security reasons or to prevent
    users from seeing the operating system, but to provide a good partition
    between binaries that everyone uses and ones that are primarily used for
    administration tasks. There is no inherent security advantage in making /
    sbin off-limits for users.
 
[20] This is particularly important as these areas will often contain both
    files initially installed by the distributor, and those added by the
    administrator.
 
[21] Examples of such configuration files include Xconfig, XF86Config, or
    system.twmrc)
 
[22] Miscellaneous architecture-independent application-specific static files
    and subdirectories must be placed in /usr/share.
 
[23] For example, the perl5 subdirectory for Perl 5 modules and libraries.
 
[24] Some executable commands such as makewhatis and sendmail have also been
    traditionally placed in /usr/lib. makewhatis is an internal binary and
    must be placed in a binary directory; users access only catman. Newer
    sendmail binaries are now placed by default in /usr/sbin. Additionally,
    systems using a sendmail-compatible mail transfer agent must provide /usr/
    sbin/sendmail as a symbolic link to the appropriate executable.
 
[25] Host-specific data for the X Window System must not be stored in /usr/lib/
    X11. Host-specific configuration files such as Xconfig or XF86Config must
    be stored in /etc/X11. This includes configuration data such as
    system.twmrc even if it is only made a symbolic link to a more global
    configuration file (probably in /usr/X11R6/lib/X11).
 
[26] The case where /usr/lib and /usr/lib<qual> are the same (one is a symbolic
    link to the other) these files and the per-application subdirectories will
    exist.
 
[27] Software placed in / or /usr may be overwritten by system upgrades (though
    we recommend that distributions do not overwrite data in /etc under these
    circumstances). For this reason, local software must not be placed outside
    of /usr/local without good reason.
 
[28] /usr/local/man may be deprecated in future FHS releases, so if all else is
    equal, making that one a symlink seems sensible.
 
[29] Locally installed system administration programs should be placed in /usr/
    local/sbin.
 
[30] Much of this data originally lived in /usr (man, doc) or /usr/lib (dict,
    terminfo, zoneinfo).
 
[31] Obviously, there are no manual pages in / because they are not required at
    boot time nor are they required in emergencies. Really.


<A
[32] For example, if /usr/local/man has no manual pages in section 4 (Devices),
NAME="AEN2209"
    then /usr/local/man/man4 may be omitted.
HREF="#FTN.AEN2209"
><SPAN
CLASS="footnote"
>[36]</SPAN
></A
></P
></DIV
><DIV
CLASS="SECTION"
><HR><H4
CLASS="SECTION"
><A
NAME="SPECIFICOPTIONS22"
>Specific Options</A
></H4
><P
>Other dynamically created fonts may also be placed in this tree,
under appropriately-named subdirectories of
<TT
CLASS="FILENAME"
>/var/cache/fonts</TT
>.</P
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="VARCACHEMANLOCALLYFORMATTEDMANUALPAG"
>/var/cache/man : Locally-formatted manual pages (optional)</A
></H3
><DIV
CLASS="SECTION"
><H4
CLASS="SECTION"
><A
NAME="PURPOSE35"
>Purpose</A
></H4
><P
>This directory provides a standard location for sites that provide a
read-only <TT
CLASS="FILENAME"
>/usr</TT
> partition, but wish to allow caching of
locally-formatted man pages.  Sites that mount <TT
CLASS="FILENAME"
>/usr</TT
> as writable
(e.g., single-user installations) may choose not to use
<TT
CLASS="FILENAME"
>/var/cache/man</TT
> and may write formatted man pages into the
<TT
CLASS="FILENAME"
>cat&lt;section&gt;</TT
> directories in <TT
CLASS="FILENAME"
>/usr/share/man</TT
> directly.  We
recommend that most sites use one of the following options instead:</P
><P
></P
><UL
><LI
STYLE="list-style-type: disc"
><P
>Preformat all manual pages alongside the unformatted versions.</P
></LI
><LI
STYLE="list-style-type: disc"
><P
>Allow no caching of formatted man pages, and require formatting to be
done each time a man page is brought up.</P
></LI
><LI
STYLE="list-style-type: disc"
><P
>Allow local caching of formatted man pages in <TT
CLASS="FILENAME"
>/var/cache/man</TT
>.</P
></LI
></UL
><P
>The structure of <TT
CLASS="FILENAME"
>/var/cache/man</TT
> needs to
reflect both the fact of multiple man page hierarchies and the
possibility of multiple language support.</P
><P
>Given an unformatted manual page that normally appears in
<TT
CLASS="FILENAME"
>&lt;path&gt;/man/&lt;locale&gt;/man&lt;section&gt;</TT
>,
the directory to place formatted man pages in is
<TT
CLASS="FILENAME"
>/var/cache/man/&lt;catpath&gt;/&lt;locale&gt;/cat&lt;section&gt;</TT
>,
where <TT
CLASS="FILENAME"
>&lt;catpath&gt;</TT
> is derived from
<TT
CLASS="FILENAME"
>&lt;path&gt;</TT
> by removing any leading
<TT
CLASS="FILENAME"
>usr</TT
> and/or trailing <TT
CLASS="FILENAME"
>share</TT
>
pathname components.  (Note that the
<TT
CLASS="FILENAME"
>&lt;locale&gt;</TT
> component may be missing.)


<A
[33] A major exception to this rule is the United Kingdom, which is `GB' in the
NAME="AEN2244"
    ISO 3166, but `UK' for most email addresses.
HREF="#FTN.AEN2244"
><SPAN
CLASS="footnote"
>[37]</SPAN
></A
></P
><P
>Man pages written to <TT
CLASS="FILENAME"
>/var/cache/man</TT
> may
eventually be transferred to the appropriate preformatted directories
in the source <TT
CLASS="FILENAME"
>man</TT
> hierarchy or expired; likewise
formatted man pages in the source <TT
CLASS="FILENAME"
>man</TT
> hierarchy
may be expired if they are not accessed for a period of time.</P
><P
>If preformatted manual pages come with a system on read-only
media (a CD-ROM, for instance), they must be installed in the source
<TT
CLASS="FILENAME"
>man</TT
> hierarchy
(e.g. <TT
CLASS="FILENAME"
>/usr/share/man/cat&lt;section&gt;</TT
>).
<TT
CLASS="FILENAME"
>/var/cache/man</TT
> is reserved as a writable cache
for formatted manual pages.</P
><DIV
CLASS="TIP"
><P
></P
><TABLE
CLASS="TIP"
WIDTH="100%"
BORDER="0"
><TR
><TD
WIDTH="25"
ALIGN="CENTER"
VALIGN="TOP"
><IMG
SRC="tip.gif"
HSPACE="5"
ALT="Tip"></TD
><TH
ALIGN="LEFT"
VALIGN="CENTER"
><B
>Rationale</B
></TH
></TR
><TR
><TD
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>Release 1.2 of the standard specified
<TT
CLASS="FILENAME"
>/var/catman</TT
> for this hierarchy.  The path has
been moved under <TT
CLASS="FILENAME"
>/var/cache</TT
> to better reflect the
dynamic nature of the formatted man pages.  The directory name has
been changed to <TT
CLASS="FILENAME"
>man</TT
> to allow for enhancing the
hierarchy to include post-processed formats other than "cat", such as
PostScript, HTML, or DVI.&#13;</P
></TD
></TR
></TABLE
></DIV
></DIV
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="VARCRASHSYSTEMCRASHDUMPS"
>/var/crash : System crash dumps (optional)</A
></H2
><DIV
CLASS="SECTION"
><H3
CLASS="SECTION"
><A
NAME="PURPOSE36"
>Purpose</A
></H3
><P
>This directory holds system crash dumps.  As of the date of this
release of the standard, system crash dumps were not supported under
Linux but may be supported by other systems which may comply with the
FHS.</P
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="VARGAMESVARIABLEGAMEDATA"
>/var/games : Variable game data (optional)</A
></H2
><DIV
CLASS="SECTION"
><H3
CLASS="SECTION"
><A
NAME="PURPOSE37"
>Purpose</A
></H3
><P
>Any variable data relating to games in <TT
CLASS="FILENAME"
>/usr</TT
>
should be placed here.  <TT
CLASS="FILENAME"
>/var/games</TT
> should hold
the variable data previously found in <TT
CLASS="FILENAME"
>/usr</TT
>;
static data, such as help text, level descriptions, and so on, must
remain elsewhere, such as
<TT
CLASS="FILENAME"
>/usr/share/games</TT
>.</P
><DIV
CLASS="TIP"
><P
></P
><TABLE
CLASS="TIP"
WIDTH="100%"
BORDER="0"
><TR
><TD
WIDTH="25"
ALIGN="CENTER"
VALIGN="TOP"
><IMG
SRC="tip.gif"
HSPACE="5"
ALT="Tip"></TD
><TH
ALIGN="LEFT"
VALIGN="CENTER"
><B
>Rationale</B
></TH
></TR
><TR
><TD
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
><TT
CLASS="FILENAME"
>/var/games</TT
> has been given a hierarchy of
its own, rather than leaving it merged in with the old
<TT
CLASS="FILENAME"
>/var/lib</TT
> as in release 1.2.  The separation
allows local control of backup strategies, permissions, and disk
usage, as well as allowing inter-host sharing and reducing clutter in
<TT
CLASS="FILENAME"
>/var/lib</TT
>.  Additionally,
<TT
CLASS="FILENAME"
>/var/games</TT
> is the path traditionally used by BSD.&#13;</P
></TD
></TR
></TABLE
></DIV
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="VARLIBVARIABLESTATEINFORMATION"
>/var/lib : Variable state information</A
></H2
><DIV
CLASS="SECTION"
><H3
CLASS="SECTION"
><A
NAME="PURPOSE38"
>Purpose</A
></H3
><P
>This hierarchy holds state information pertaining to an
application or the system.  State information is data that programs
modify while they run, and that pertains to one specific host.  Users
must never need to modify files in <TT
CLASS="FILENAME"
>/var/lib</TT
> to
configure a package's operation.</P
><P
>State information is generally used to preserve the condition of
an application (or a group of inter-related applications) between
invocations and between different instances of the same application.
State information should generally remain valid after a reboot, should
not be logging output, and should not be spooled data.</P
><P
>An application (or a group of inter-related applications) must
use a subdirectory of <TT
CLASS="FILENAME"
>/var/lib</TT
> for its data.
There is one required subdirectory,
<TT
CLASS="FILENAME"
>/var/lib/misc</TT
>, which is intended for state files
that don't need a subdirectory; the other subdirectories should only
be present if the application in question is included in the
distribution.


<A
[34] Some such files include: airport, birthtoken, eqnchar, getopt,
NAME="AEN2295"
    gprof.callg, gprof.flat, inter.phone, ipfw.samp.filters,
HREF="#FTN.AEN2295"
    ipfw.samp.scripts, keycap.pcvt, mail.help, mail.tildehelp, man.template,
><SPAN
    map3270, mdoc.template, more.help, na.phone, nslookup.help, operator,
CLASS="footnote"
    scsi_modes, sendmail.hf, style, units.lib, vgrindefs, vgrindefs.db,
>[38]</SPAN
    zipcodes
></A
></P
><P
><TT
CLASS="FILENAME"
>/var/lib/&lt;name&gt;</TT
> is the location that
must be used for all distribution packaging support.  Different
distributions may use different names, of course.</P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="REQUIREMENTS13"
>Requirements</A
></H3
><P
>The following directories, or symbolic links to directories, are
required in <TT
CLASS="FILENAME"
>/var/lib</TT
>:</P
><DIV
CLASS="INFORMALTABLE"
><P
></P
><A
NAME="AEN2305"
></A
><TABLE
BORDER="0"
FRAME="void"
CLASS="CALSTABLE"
><COL><COL><THEAD
><TR
><TH
>Directory</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><TT
CLASS="FILENAME"
>misc</TT
></TD
><TD
>Miscellaneous state data</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="SPECIFICOPTIONS23"
>Specific Options</A
></H3
><P
>The following directories, or symbolic links to directories, must be in <TT
CLASS="FILENAME"
>/var/lib</TT
>, if the
corresponding subsystem is installed:</P
><DIV
CLASS="INFORMALTABLE"
><P
></P
><A
NAME="AEN2320"
></A
><TABLE
BORDER="0"
FRAME="void"
CLASS="CALSTABLE"
><COL><COL><THEAD
><TR
><TH
>Directory</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
>&lt;editor&gt;</TD
><TD
>Editor backup files and state (optional)</TD
></TR
><TR
><TD
>&lt;pkgtool&gt;</TD
><TD
>Packaging support files (optional)</TD
></TR
><TR
><TD
>&lt;package&gt;</TD
><TD
>State data for packages and subsystems (optional)</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>hwclock</B
></TD
><TD
>State directory for hwclock (optional)</TD
></TR
><TR
><TD
><B
CLASS="COMMAND"
>xdm</B
></TD
><TD
>X display manager variable data (optional)</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="VARLIBLTEDITORGTEDITORBACKUPFILESAN"
>/var/lib/&lt;editor&gt; : Editor backup files and state (optional)</A
></H3
><DIV
CLASS="SECTION"
><H4
CLASS="SECTION"
><A
NAME="PURPOSE39"
>Purpose</A
></H4
><P
>These directories contain saved files generated by any
unexpected termination of an editor (e.g., <B
CLASS="COMMAND"
>elvis</B
>,
<B
CLASS="COMMAND"
>jove</B
>, <B
CLASS="COMMAND"
>nvi</B
>).</P
><P
>Other editors may not require a directory for crash-recovery
files, but may require a well-defined place to store other information
while the editor is running. This information should be stored in a
subdirectory under <TT
CLASS="FILENAME"
>/var/lib</TT
> (for example, GNU
Emacs would place lock files in
<TT
CLASS="FILENAME"
>/var/lib/emacs/lock</TT
>).</P
><P
>Future editors may require additional state information beyond
crash-recovery files and lock files &mdash; this information should
also be placed under
<TT
CLASS="FILENAME"
>/var/lib/&lt;editor&gt;</TT
>.</P
><DIV
CLASS="TIP"
><P
></P
><TABLE
CLASS="TIP"
WIDTH="100%"
BORDER="0"
><TR
><TD
WIDTH="25"
ALIGN="CENTER"
VALIGN="TOP"
><IMG
SRC="tip.gif"
HSPACE="5"
ALT="Tip"></TD
><TH
ALIGN="LEFT"
VALIGN="CENTER"
><B
>Rationale</B
></TH
></TR
><TR
><TD
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>Previous Linux releases, as well as all commercial vendors, use
<TT
CLASS="FILENAME"
>/var/preserve</TT
> for vi or its clones. However,
each editor uses its own format for these crash-recovery files, so a
separate directory is needed for each editor.</P
><P
>Editor-specific lock files are usually quite different from the
device or resource lock files that are stored in
<TT
CLASS="FILENAME"
>/var/lock</TT
> and, hence, are stored under
<TT
CLASS="FILENAME"
>/var/lib</TT
>.&#13;</P
></TD
></TR
></TABLE
></DIV
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="VARLIBHWCLOCKSTATEDIRECTORYFORHWCLO"
>/var/lib/hwclock : State directory for hwclock (optional)</A
></H3
><DIV
CLASS="SECTION"
><H4
CLASS="SECTION"
><A
NAME="PURPOSE40"
>Purpose</A
></H4
><P
>This directory contains the file
<TT
CLASS="FILENAME"
>/var/lib/hwclock/adjtime</TT
>.</P
><DIV
CLASS="TIP"
><P
></P
><TABLE
CLASS="TIP"
WIDTH="100%"
BORDER="0"
><TR
><TD
WIDTH="25"
ALIGN="CENTER"
VALIGN="TOP"
><IMG
SRC="tip.gif"
HSPACE="5"
ALT="Tip"></TD
><TH
ALIGN="LEFT"
VALIGN="CENTER"
><B
>Rationale</B
></TH
></TR
><TR
><TD
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>In FHS 2.1, this file was <TT
CLASS="FILENAME"
>/etc/adjtime</TT
>, but
as <B
CLASS="COMMAND"
>hwclock</B
> updates it, that was obviously
incorrect.&#13;</P
></TD
></TR
></TABLE
></DIV
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="VARLIBMISCMISCELLANEOUSVARIABLEDATA"
>/var/lib/misc : Miscellaneous variable data</A
></H3
><DIV
CLASS="SECTION"
><H4
CLASS="SECTION"
><A
NAME="PURPOSE41"
>Purpose</A
></H4
><P
>This directory contains variable data not placed in a
subdirectory in <TT
CLASS="FILENAME"
>/var/lib</TT
>.  An attempt should be
made to use relatively unique names in this directory to avoid
namespace conflicts.


<A
[35] Generally, source should not be built within this hierarchy.
NAME="AEN2381"
HREF="#FTN.AEN2381"
><SPAN
CLASS="footnote"
>[39]</SPAN
></A
></P
></DIV
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="VARLOCKLOCKFILES"
>/var/lock : Lock files</A
></H2
><DIV
CLASS="SECTION"
><H3
CLASS="SECTION"
><A
NAME="PURPOSE42"
>Purpose</A
></H3
><P
>Lock files should be stored within the
<TT
CLASS="FILENAME"
>/var/lock</TT
> directory structure.</P
><P
>Lock files for devices and other resources shared by multiple
applications, such as the serial device lock files that were
originally found in either <TT
CLASS="FILENAME"
>/usr/spool/locks</TT
> or
<TT
CLASS="FILENAME"
>/usr/spool/uucp</TT
>, must now be stored in
<TT
CLASS="FILENAME"
>/var/lock</TT
>.  The naming convention which must be
used is "LCK.." followed by the base name of the device.  For example,
to lock /dev/ttyS0 the file "LCK..ttyS0" would be created.


<A
[36] This standard does not currently incorporate the TeX Directory Structure
NAME="AEN2396"
    (a document that describes the layout TeX files and directories), but it
HREF="#FTN.AEN2396"
    may be useful reading. It is located at ftp://ctan.tug.org/tex/
><SPAN
CLASS="footnote"
>[40]</SPAN
></A
></P
><P
>The format used for the contents of such lock files must be the
HDB UUCP lock file format.  The HDB format is to store the process
identifier (PID) as a ten byte ASCII decimal number, with a trailing
newline.  For example, if process 1230 holds a lock file, it would
contain the eleven characters: space, space, space, space, space,
space, one, two, three, zero, and newline.</P
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="VARLOGLOGFILESANDDIRECTORIES"
>/var/log : Log files and directories</A
></H2
><DIV
CLASS="SECTION"
><H3
CLASS="SECTION"
><A
NAME="PURPOSE43"
>Purpose</A
></H3
><P
>This directory contains miscellaneous log files.  Most logs must
be written to this directory or an appropriate subdirectory.</P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="SPECIFICOPTIONS24"
>Specific Options</A
></H3
><P
>The following files, or symbolic links to files, must be in
<TT
CLASS="FILENAME"
>/var/log</TT
>, if the corresponding subsystem is
installed:</P
><DIV
CLASS="INFORMALTABLE"
><P
></P
><A
NAME="AEN2410"
></A
><TABLE
BORDER="0"
FRAME="void"
CLASS="CALSTABLE"
><COL><COL><THEAD
><TR
><TH
>File</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><TT
CLASS="FILENAME"
>lastlog</TT
></TD
><TD
>record of last login of each user</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>messages</TT
></TD
><TD
>system messages from <B
CLASS="COMMAND"
>syslogd</B
></TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>wtmp</TT
></TD
><TD
>record of all logins and logouts</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="VARMAILUSERMAILBOXFILES"
>/var/mail : User mailbox files (optional)</A
></H2
><DIV
CLASS="SECTION"
><H3
CLASS="SECTION"
><A
NAME="PURPOSE44"
>Purpose</A
></H3
><P
>The mail spool must be accessible through
<TT
CLASS="FILENAME"
>/var/mail</TT
> and the mail spool files must take the
form <TT
CLASS="FILENAME"
>&lt;username&gt;</TT
>.
<A
NAME="AEN2437"
HREF="#FTN.AEN2437"
><SPAN
CLASS="footnote"
>[41]</SPAN
></A
></P
><P
>User mailbox files in this location must be stored in the standard
UNIX mailbox format.</P
><DIV
CLASS="TIP"
><P
></P
><TABLE
CLASS="TIP"
WIDTH="100%"
BORDER="0"
><TR
><TD
WIDTH="25"
ALIGN="CENTER"
VALIGN="TOP"
><IMG
SRC="tip.gif"
HSPACE="5"
ALT="Tip"></TD
><TH
ALIGN="LEFT"
VALIGN="CENTER"
><B
>Rationale</B
></TH
></TR
><TR
><TD
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>The logical location for this directory was changed from
<TT
CLASS="FILENAME"
>/var/spool/mail</TT
> in order to bring FHS in-line
with nearly every UNIX implementation.  This change is important for
inter-operability since a single <TT
CLASS="FILENAME"
>/var/mail</TT
> is
often shared between multiple hosts and multiple UNIX implementations
(despite NFS locking issues).</P
><P
>It is important to note that there is no requirement to
physically move the mail spool to this location.  However, programs
and header files must be changed to use
<TT
CLASS="FILENAME"
>/var/mail</TT
>.&#13;</P
></TD
></TR
></TABLE
></DIV
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="VAROPTVARIABLEDATAFOROPT"
>/var/opt : Variable data for /opt</A
></H2
><DIV
CLASS="SECTION"
><H3
CLASS="SECTION"
><A
NAME="PURPOSE45"
>Purpose</A
></H3
><P
>Variable data of the packages in <TT
CLASS="FILENAME"
>/opt</TT
> must
be installed in <TT
CLASS="FILENAME"
>/var/opt/&lt;subdir&gt;</TT
>, where
<TT
CLASS="FILENAME"
>&lt;subdir&gt;</TT
> is the name of the subtree in
<TT
CLASS="FILENAME"
>/opt</TT
> where the static data from an add-on
software package is stored, except where superseded by another file in
<TT
CLASS="FILENAME"
>/etc</TT
>. No structure is imposed on the internal
arrangement of <TT
CLASS="FILENAME"
>/var/opt/&lt;subdir&gt;</TT
>.</P
><DIV
CLASS="TIP"
><P
></P
><TABLE
CLASS="TIP"
WIDTH="100%"
BORDER="0"
><TR
><TD
WIDTH="25"
ALIGN="CENTER"
VALIGN="TOP"
><IMG
SRC="tip.gif"
HSPACE="5"
ALT="Tip"></TD
><TH
ALIGN="LEFT"
VALIGN="CENTER"
><B
>Rationale</B
></TH
></TR
><TR
><TD
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>Refer to the rationale for <TT
CLASS="FILENAME"
>/opt</TT
>.&#13;</P
></TD
></TR
></TABLE
></DIV
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="VARRUNRUNTIMEVARIABLEDATA"
>/var/run : Run-time variable data</A
></H2
><DIV
CLASS="SECTION"
><H3
CLASS="SECTION"
><A
NAME="PURPOSE46"
>Purpose</A
></H3
><P
>This directory contains system information data describing the
system since it was booted.  Files under this directory must be
cleared (removed or truncated as appropriate) at the beginning of the
boot process.  Programs may have a subdirectory of
<TT
CLASS="FILENAME"
>/var/run</TT
>; this is encouraged for programs that
use more than one run-time file.


<A
[37] For example, /usr/share/man/man1/ls.1 is formatted into /var/cache/man/
NAME="AEN2469"
    cat1/ls.1, and /usr/X11R6/man/<locale>/man3/XtClass.3x into /var/cache/man
HREF="#FTN.AEN2469"
    /X11R6/<locale>/cat3/XtClass.3x.
><SPAN
CLASS="footnote"
>[42]</SPAN
></A
>


Process identifier (PID) files, which were originally placed in
[38] An important difference between this version of this standard and previous
<TT
    ones is that applications are now required to use a subdirectory of /var/
CLASS="FILENAME"
    lib.
>/etc</TT
>, must be placed in
<TT
CLASS="FILENAME"
>/var/run</TT
>.  The naming convention for PID files is
<TT
CLASS="FILENAME"
>&lt;program-name&gt;.pid</TT
>.  For example, the
<B
CLASS="COMMAND"
>crond</B
> PID file is named
<TT
CLASS="FILENAME"
>/var/run/crond.pid</TT
>.</P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="REQUIREMENTS14"
>Requirements</A
></H3
><P
>The internal format of PID files remains unchanged.  The file
must consist of the process identifier in ASCII-encoded decimal,
followed by a newline character.  For example, if
<B
CLASS="COMMAND"
>crond</B
> was process number 25,
<TT
CLASS="FILENAME"
>/var/run/crond.pid</TT
> would contain three
characters: two, five, and newline.</P
><P
>Programs that read PID files should be somewhat flexible in what
they accept; i.e., they should ignore extra whitespace, leading
zeroes, absence of the trailing newline, or additional lines in the
PID file.  Programs that create PID files should use the simple
specification located in the above paragraph.</P
><P
>The <TT
CLASS="FILENAME"
>utmp</TT
> file, which stores information
about who is currently using the system, is located in this
directory.</P
><P
>System programs that maintain transient UNIX-domain sockets must place
them in this directory.</P
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="VARSPOOLAPPLICATIONSPOOLDATA"
>/var/spool : Application spool data</A
></H2
><DIV
CLASS="SECTION"
><H3
CLASS="SECTION"
><A
NAME="PURPOSE47"
>Purpose</A
></H3
><P
><TT
CLASS="FILENAME"
>/var/spool</TT
> contains data which is awaiting
some kind of later processing.  Data in
<TT
CLASS="FILENAME"
>/var/spool</TT
> represents work to be done in the
future (by a program, user, or administrator); often data is deleted
after it has been processed.


<A
[39] This hierarchy should contain files stored in /var/db in current BSD
NAME="AEN2493"
    releases. These include locate.database and mountdtab, and the kernel
HREF="#FTN.AEN2493"
    symbol database(s).
><SPAN
CLASS="footnote"
>[43]</SPAN
></A
></P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="SPECIFICOPTIONS25"
>Specific Options</A
></H3
><P
>The following directories, or symbolic links to directories,
must be in <TT
CLASS="FILENAME"
>/var/spool</TT
>, if the corresponding
subsystem is installed:</P
><DIV
CLASS="INFORMALTABLE"
><P
></P
><A
NAME="AEN2501"
></A
><TABLE
BORDER="0"
FRAME="void"
CLASS="CALSTABLE"
><COL><COL><THEAD
><TR
><TH
>Directory</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><TT
CLASS="FILENAME"
>lpd</TT
></TD
><TD
>Printer spool directory (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>mqueue</TT
></TD
><TD
>Outgoing mail queue (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>news</TT
></TD
><TD
>News spool directory (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>rwho</TT
></TD
><TD
>Rwhod files (optional)</TD
></TR
><TR
><TD
><TT
CLASS="FILENAME"
>uucp</TT
></TD
><TD
>Spool directory for UUCP (optional)</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="VARSPOOLLPDLINEPRINTERDAEMONPRINTQU"
>/var/spool/lpd : Line-printer daemon print queues (optional)</A
></H3
><DIV
CLASS="SECTION"
><H4
CLASS="SECTION"
><A
NAME="PURPOSE48"
>Purpose</A
></H4
><P
>The lock file for <B
CLASS="COMMAND"
>lpd</B
>,
<TT
CLASS="FILENAME"
>lpd.lock</TT
>, must be placed in
<TT
CLASS="FILENAME"
>/var/spool/lpd</TT
>.  It is suggested that the lock
file for each printer be placed in the spool directory for that
specific printer and named <TT
CLASS="FILENAME"
>lock</TT
>.</P
></DIV
><DIV
CLASS="SECTION"
><HR><H4
CLASS="SECTION"
><A
NAME="SPECIFICOPTIONS26"
>Specific Options</A
></H4
><DIV
CLASS="INFORMALTABLE"
><P
></P
><A
NAME="AEN2539"
></A
><TABLE
BORDER="0"
FRAME="void"
CLASS="CALSTABLE"
><COL><COL><THEAD
><TR
><TH
>Directory</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><TT
CLASS="FILENAME"
>printer</TT
></TD
><TD
>Spools for a specific printer (optional)</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="VARSPOOLRWHORWHODFILES"
>/var/spool/rwho : Rwhod files (optional)</A
></H3
><DIV
CLASS="SECTION"
><H4
CLASS="SECTION"
><A
NAME="PURPOSE49"
>Purpose</A
></H4
><P
>This directory holds the <B
CLASS="COMMAND"
>rwhod</B
> information
for other systems on the local net.</P
><DIV
CLASS="TIP"
><P
></P
><TABLE
CLASS="TIP"
WIDTH="100%"
BORDER="0"
><TR
><TD
WIDTH="25"
ALIGN="CENTER"
VALIGN="TOP"
><IMG
SRC="tip.gif"
HSPACE="5"
ALT="Tip"></TD
><TH
ALIGN="LEFT"
VALIGN="CENTER"
><B
>Rationale</B
></TH
></TR
><TR
><TD
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>Some BSD releases use <TT
CLASS="FILENAME"
>/var/rwho</TT
> for this
data; given its historical location in <TT
CLASS="FILENAME"
>/var/spool</TT
>
on other systems and its approximate fit to the definition of
`spooled' data, this location was deemed more appropriate.</P
></TD
></TR
></TABLE
></DIV
></DIV
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="VARTMPTEMPORARYFILESPRESERVEDBETWEE"
>/var/tmp : Temporary files preserved between system reboots</A
></H2
><DIV
CLASS="SECTION"
><H3
CLASS="SECTION"
><A
NAME="PURPOSE50"
>Purpose</A
></H3
><P
>The <TT
CLASS="FILENAME"
>/var/tmp</TT
> directory is made available
for programs that require temporary files or directories that are
preserved between system reboots.  Therefore, data stored in
<TT
CLASS="FILENAME"
>/var/tmp</TT
> is more persistent than data in
<TT
CLASS="FILENAME"
>/tmp</TT
>.</P
><P
>Files and directories located in <TT
CLASS="FILENAME"
>/var/tmp</TT
>
must not be deleted when the system is booted.  Although data stored
in <TT
CLASS="FILENAME"
>/var/tmp</TT
> is typically deleted in a
site-specific manner, it is recommended that deletions occur at a less
frequent interval than <TT
CLASS="FILENAME"
>/tmp</TT
>.</P
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="VARYPNETWORKINFORMATIONSERVICE"
>/var/yp : Network Information Service (NIS) database files (optional)</A
></H2
><DIV
CLASS="SECTION"
><H3
CLASS="SECTION"
><A
NAME="PURPOSE51"
>Purpose</A
></H3
><P
>Variable data for the Network Information Service (NIS),
formerly known as the Sun Yellow Pages (YP), must be placed in this
directory.</P
><DIV
CLASS="TIP"
><P
></P
><TABLE
CLASS="TIP"
WIDTH="100%"
BORDER="0"
><TR
><TD
WIDTH="25"
ALIGN="CENTER"
VALIGN="TOP"
><IMG
SRC="tip.gif"
HSPACE="5"
ALT="Tip"></TD
><TH
ALIGN="LEFT"
VALIGN="CENTER"
><B
>Rationale</B
></TH
></TR
><TR
><TD
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
><TT
CLASS="FILENAME"
>/var/yp</TT
> is the standard directory for NIS
(YP) data and is almost exclusively used in NIS documentation and
systems.


<A
[40] Then, anything wishing to use /dev/ttyS0 can read the lock file and act
NAME="AEN2582"
    accordingly (all locks in /var/lock should be world-readable).
HREF="#FTN.AEN2582"
><SPAN
CLASS="footnote"
>[44]</SPAN
></A
></P
></TD
></TR
></TABLE
></DIV
></DIV
></DIV
></DIV
><DIV
CLASS="CHAPTER"
><HR><H1
><A
NAME="OPERATINGSYSTEMSPECIFICANNEX"
></A
>Chapter 6. Operating System Specific Annex</H1
><P
>This section is for additional requirements and recommendations
that only apply to a specific operating system.  The material in this
section should never conflict with the base standard.</P
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="LINUX"
>Linux</A
></H2
><P
>This is the annex for the Linux operating system.</P
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="ROOTDIRECTORY"
>/ : Root directory</A
></H3
><P
>On Linux systems, if the kernel is located in
<TT
CLASS="FILENAME"
>/</TT
>, we recommend using the names
<TT
CLASS="FILENAME"
>vmlinux</TT
> or <TT
CLASS="FILENAME"
>vmlinuz</TT
>, which
have been used in recent Linux kernel source packages.</P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="BINESSENTIALUSERCOMMANDBINARIES2"
>/bin : Essential user command binaries (for use by all users)</A
></H3
><P
>Linux systems which require them place these additional files into
<TT
CLASS="FILENAME"
>/bin</TT
>:</P
><P
></P
><UL
><LI
><P
><B
CLASS="COMMAND"
>setserial</B
></P
></LI
></UL
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="DEVDEVICESANDSPECIALFILES"
>/dev : Devices and special files</A
></H3
><P
>The following devices must exist under /dev.  


<P
[41] Note that /var/mail may be a symbolic link to another directory.
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="FILENAME"
>/dev/null</TT
></DT
><DD
><P
>All data written to this device is discarded. A read from this device
will return an EOF condition.</P
></DD
><DT
><TT
CLASS="FILENAME"
>/dev/zero</TT
></DT
><DD
><P
>This device is a source of zeroed out data. All data written to this
device is discarded. A read from this device will return as many bytes
containing the value zero as was requested.</P
></DD
><DT
><TT
CLASS="FILENAME"
>/dev/tty</TT
></DT
><DD
><P
>This device is a synonym for the controlling terminal of a
process. Once this device is opened, all reads and writes will behave
as if the actual controlling terminal device had been opened.</P
></DD
></DL
></DIV
>


<DIV
[42] /var/run should be unwritable for unprivileged users (root or users
CLASS="TIP"
    running daemons); it is a major security problem if any user can write in
><P
    this directory.
></P
><TABLE
CLASS="TIP"
WIDTH="100%"
BORDER="0"
><TR
><TD
WIDTH="25"
ALIGN="CENTER"
VALIGN="TOP"
><IMG
SRC="tip.gif"
HSPACE="5"
ALT="Tip"></TD
><TH
ALIGN="LEFT"
VALIGN="CENTER"
><B
>Rationale</B
></TH
></TR
><TR
><TD
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>Previous versions of the FHS had stricter requirements for
<TT
CLASS="FILENAME"
>/dev</TT
>. Other devices may also exist in
/dev. Device names may exist as symbolic links to other device nodes
located in /dev or subdirectories of /dev. There is no requirement
concerning major/minor number values.</P
></TD
></TR
></TABLE
></DIV
>&#13;</P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="ETCHOSTSPECIFICSYSTEMCONFIGURATION2"
>/etc : Host-specific system configuration</A
></H3
><P
>Linux systems which require them place these additional files into
<TT
CLASS="FILENAME"
>/etc</TT
>.</P
><P
></P
><UL
><LI
><P
><TT
CLASS="FILENAME"
>lilo.conf</TT
></P
></LI
></UL
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="LIB64"
>/lib64 and /lib32 : 64/32-bit libraries (architecture dependent)</A
></H3
><P
>&#13;The 64-bit architectures PPC64, s390x, sparc64 and AMD64 must place
64-bit libraries in <TT
CLASS="FILENAME"
>/lib64</TT
>, and 32-bit
(or 31-bit on s390) libraries in <TT
CLASS="FILENAME"
>/lib</TT
>.</P
><P
>The 64-bit architecture IA64 must place 64-bit libraries in
<TT
CLASS="FILENAME"
>/lib</TT
>.  


<DIV
[43] UUCP lock files must be placed in /var/lock. See the above section on /var
CLASS="TIP"
    /lock.
><P
></P
><TABLE
CLASS="TIP"
WIDTH="100%"
BORDER="0"
><TR
><TD
WIDTH="25"
ALIGN="CENTER"
VALIGN="TOP"
><IMG
SRC="tip.gif"
HSPACE="5"
ALT="Tip"></TD
><TH
ALIGN="LEFT"
VALIGN="CENTER"
><B
>Rationale</B
></TH
></TR
><TR
><TD
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>This is a refinement of the general rules for
<TT
CLASS="FILENAME"
>/lib&lt;qual&gt;</TT
> and
<TT
CLASS="FILENAME"
>/usr/lib&lt;qual&gt;</TT
>.  The architectures PPC64,
s390x, sparc64 and AMD64 support support both 32-bit (for s390 more
precise 31-bit) and 64-bit programs.  Using <TT
CLASS="FILENAME"
>lib</TT
>
for 32-bit binaries allows existing binaries from the 32-bit systems
to work without any changes: such binaries are expected to be numerous.
IA-64 uses a different scheme, reflecting the deprecation of 32-bit
binaries (and hence libraries) on that architecture.</P
></TD
></TR
></TABLE
></DIV
></P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="PROCKERNELANDPROCESSINFORMATIONVIR"
>/proc : Kernel and process information virtual filesystem</A
></H3
><P
>The <TT
CLASS="FILENAME"
>proc</TT
> filesystem is the de-facto
standard Linux method for handling process and system information,
rather than <TT
CLASS="FILENAME"
>/dev/kmem</TT
> and other similar methods.
We strongly encourage this for the storage and retrieval of process
information as well as other kernel and memory information.</P
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="SBINESSENTIALSYSTEMBINARIES"
>/sbin : Essential system binaries</A
></H3
><P
>Linux systems place these additional files into <TT
CLASS="FILENAME"
>/sbin</TT
>.</P
><P
></P
><UL
><LI
STYLE="list-style-type: disc"
><P
>Second extended filesystem commands (optional):</P
><P
></P
><UL
><LI
STYLE="list-style-type: disc"
><P
><B
CLASS="COMMAND"
>badblocks</B
></P
></LI
><LI
STYLE="list-style-type: disc"
><P
><B
CLASS="COMMAND"
>dumpe2fs</B
></P
></LI
><LI
STYLE="list-style-type: disc"
><P
><B
CLASS="COMMAND"
>e2fsck</B
></P
></LI
><LI
STYLE="list-style-type: disc"
><P
><B
CLASS="COMMAND"
>mke2fs</B
></P
></LI
><LI
STYLE="list-style-type: disc"
><P
><B
CLASS="COMMAND"
>mklost+found</B
></P
></LI
><LI
STYLE="list-style-type: disc"
><P
><B
CLASS="COMMAND"
>tune2fs</B
></P
></LI
></UL
></LI
><LI
STYLE="list-style-type: disc"
><P
>Boot-loader map installer (optional):</P
><P
></P
><UL
><LI
STYLE="list-style-type: disc"
><P
><B
CLASS="COMMAND"
>lilo</B
></P
></LI
></UL
></LI
></UL
><P
>Optional files for /sbin:</P
><P
></P
><UL
><LI
STYLE="list-style-type: disc"
><P
>Static binaries:</P
><P
></P
><UL
><LI
STYLE="list-style-type: disc"
><P
><B
CLASS="COMMAND"
>ldconfig</B
></P
></LI
><LI
STYLE="list-style-type: disc"
><P
><B
CLASS="COMMAND"
>sln</B
></P
></LI
><LI
STYLE="list-style-type: disc"
><P
><B
CLASS="COMMAND"
>ssync</B
></P
></LI
></UL
><P
>Static <B
CLASS="COMMAND"
>ln</B
> (<B
CLASS="COMMAND"
>sln</B
>) and
static <B
CLASS="COMMAND"
>sync</B
> (<B
CLASS="COMMAND"
>ssync</B
>) are
useful when things go wrong.  The primary use of
<B
CLASS="COMMAND"
>sln</B
> (to repair incorrect symlinks in
<TT
CLASS="FILENAME"
>/lib</TT
> after a poorly orchestrated upgrade) is no
longer a major concern now that the <B
CLASS="COMMAND"
>ldconfig</B
>
program (usually located in <TT
CLASS="FILENAME"
>/usr/sbin</TT
>) exists and
can act as a guiding hand in upgrading the dynamic libraries.  Static
<B
CLASS="COMMAND"
>sync</B
> is useful in some emergency situations.
Note that these need not be statically linked versions of the standard
<B
CLASS="COMMAND"
>ln</B
> and <B
CLASS="COMMAND"
>sync</B
>, but may
be.</P
><P
>The <B
CLASS="COMMAND"
>ldconfig</B
> binary is optional for
<TT
CLASS="FILENAME"
>/sbin</TT
> since a site may choose to run
<B
CLASS="COMMAND"
>ldconfig</B
> at boot time, rather than only when
upgrading the shared libraries.  (It's not clear whether or not it is
advantageous to run <B
CLASS="COMMAND"
>ldconfig</B
> on each boot.)  Even
so, some people like <B
CLASS="COMMAND"
>ldconfig</B
> around for the
following (all too common) situation:</P
><P
></P
><OL
TYPE="1"
><LI
STYLE="list-style-type: disc"
><P
>I've just removed <TT
CLASS="FILENAME"
>/lib/&lt;file&gt;</TT
>.</P
></LI
><LI
STYLE="list-style-type: disc"
><P
>I can't find out the name of the library because <B
CLASS="COMMAND"
>ls</B
> is
dynamically linked, I'm using a shell that doesn't have <B
CLASS="COMMAND"
>ls</B
>
built-in, and I don't know about using "<B
CLASS="COMMAND"
>echo *</B
>" as a
replacement.</P
></LI
><LI
STYLE="list-style-type: disc"
><P
>I have a static <B
CLASS="COMMAND"
>sln</B
>, but I don't know what to call the link.</P
></LI
></OL
></LI
><LI
STYLE="list-style-type: disc"
><P
>Miscellaneous:</P
><P
></P
><UL
><LI
STYLE="list-style-type: disc"
><P
><B
CLASS="COMMAND"
>ctrlaltdel</B
></P
></LI
><LI
STYLE="list-style-type: disc"
><P
><B
CLASS="COMMAND"
>kbdrate</B
></P
></LI
></UL
><P
>So as to cope with the fact that some keyboards come up with
such a high repeat rate as to be unusable,
<B
CLASS="COMMAND"
>kbdrate</B
> may be installed in
<TT
CLASS="FILENAME"
>/sbin</TT
> on some systems.</P
><P
>Since the default action in the kernel for the Ctrl-Alt-Del key
combination is an instant hard reboot, it is generally advisable to
disable the behavior before mounting the root filesystem in read-write
mode.  Some <B
CLASS="COMMAND"
>init</B
> suites are able to disable
Ctrl-Alt-Del, but others may require the
<B
CLASS="COMMAND"
>ctrlaltdel</B
> program, which may be installed in
<TT
CLASS="FILENAME"
>/sbin</TT
> on those systems.</P
></LI
></UL
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="USRINCLUDEHEADERFILESINCLUDEDBYCP"
>/usr/include : Header files included by C programs</A
></H3
><P
>These symbolic links are required if a C or C++ compiler is
installed and only for systems not based on glibc.</P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="SCREEN"
>    /usr/include/asm -&gt; /usr/src/linux/include/asm-&lt;arch&gt;
    /usr/include/linux -&gt; /usr/src/linux/include/linux</PRE
></TD
></TR
></TABLE
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="USRSRCSOURCECODE2"
>/usr/src : Source code</A
></H3
><P
>For systems based on glibc, there are no specific guidelines for
this directory.  For systems based on Linux libc revisions prior to
glibc, the following guidelines and rationale apply:</P
><P
>The only source code that should be placed in a specific
location is the Linux kernel source code.  It is located in
<TT
CLASS="FILENAME"
>/usr/src/linux</TT
>.</P
><P
>If a C or C++ compiler is installed, but the complete Linux
kernel source code is not installed, then the include files from the
kernel source code must be located in these directories:</P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="SCREEN"
>    /usr/src/linux/include/asm-&lt;arch&gt;
    /usr/src/linux/include/linux</PRE
></TD
></TR
></TABLE
><P
><TT
CLASS="FILENAME"
>&lt;arch&gt;</TT
> is the name of the system
architecture.</P
><DIV
CLASS="NOTE"
><P
></P
><TABLE
CLASS="NOTE"
WIDTH="100%"
BORDER="0"
><TR
><TD
WIDTH="25"
ALIGN="CENTER"
VALIGN="TOP"
><IMG
SRC="/usr/share/sgml/docbook/stylesheet/dsssl/modular/images/note.gif"
HSPACE="5"
ALT="Note"></TD
><TH
ALIGN="LEFT"
VALIGN="CENTER"
><B
>Note</B
></TH
></TR
><TR
><TD
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
> <TT
CLASS="FILENAME"
>/usr/src/linux</TT
>
may be a symbolic link to a kernel source code tree.</P
></TD
></TR
></TABLE
></DIV
><DIV
CLASS="TIP"
><P
></P
><TABLE
CLASS="TIP"
WIDTH="100%"
BORDER="0"
><TR
><TD
WIDTH="25"
ALIGN="CENTER"
VALIGN="TOP"
><IMG
SRC="tip.gif"
HSPACE="5"
ALT="Tip"></TD
><TH
ALIGN="LEFT"
VALIGN="CENTER"
><B
>Rationale</B
></TH
></TR
><TR
><TD
>&nbsp;</TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
><P
>It is important that the kernel include files be located in
<TT
CLASS="FILENAME"
>/usr/src/linux</TT
> and not in
<TT
CLASS="FILENAME"
>/usr/include</TT
> so there are no problems when system
administrators upgrade their kernel version for the first time.&#13;</P
></TD
></TR
></TABLE
></DIV
></DIV
><DIV
CLASS="SECTION"
><HR><H3
CLASS="SECTION"
><A
NAME="VARSPOOLCRONCRONANDATJOBS"
>/var/spool/cron : cron and at jobs</A
></H3
><P
>This directory contains the variable data for the
<B
CLASS="COMMAND"
>cron</B
> and <B
CLASS="COMMAND"
>at</B
> programs.</P
></DIV
></DIV
></DIV
><DIV
CLASS="CHAPTER"
><HR><H1
><A
NAME="APPENDIX"
></A
>Chapter 7. Appendix</H1
><DIV
CLASS="SECTION"
><H2
CLASS="SECTION"
><A
NAME="THEFHSMAILINGLIST"
>The FHS mailing list</A
></H2
><P
>The FHS mailing list is located at
&lt;freestandards-fhs-discuss@lists.sourceforge.net&gt;. You can
subscribe to the mailing list at this page <A
HREF="http://sourceforge.net/projects/freestandards/"
TARGET="_top"
>http://sourceforge.net/projects/freestandards/</A
>.</P
><P
>Thanks to Network Operations at the University of California at
San Diego who allowed us to use their excellent mailing list
server.</P
><P
>As noted in the introduction, please do not send mail to the mailing
list without first contacting the FHS editor or a listed contributor.</P
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="BACKGROUNDOFTHEFHS"
>Background of the FHS</A
></H2
><P
>The process of developing a standard filesystem hierarchy began
in August 1993 with an effort to restructure the file and directory
structure of Linux.  The FSSTND, a filesystem hierarchy standard
specific to the Linux operating system, was released on February 14,
1994.  Subsequent revisions were released on October 9, 1994 and March
28, 1995.</P
><P
>In early 1995, the goal of developing a more comprehensive
version of FSSTND to address not only Linux, but other UNIX-like
systems was adopted with the help of members of the BSD development
community.  As a result, a concerted effort was made to focus on
issues that were general to UNIX-like systems.  In recognition of this
widening of scope, the name of the standard was changed to Filesystem
Hierarchy Standard or FHS for short.</P
><P
>Volunteers who have contributed extensively to this standard are
listed at the end of this document.  This standard represents a
consensus view of those and other contributors.</P
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="GENERALGUIDELINES"
>General Guidelines</A
></H2
><P
>Here are some of the guidelines that have been used in the development
of this standard:</P
><P
></P
><UL
><LI
STYLE="list-style-type: disc"
><P
>Solve technical problems while limiting transitional difficulties.</P
></LI
><LI
STYLE="list-style-type: disc"
><P
>Make the specification reasonably stable.</P
></LI
><LI
STYLE="list-style-type: disc"
><P
>Gain the approval of distributors, developers, and other decision-makers
in relevant development groups and encourage their participation.</P
></LI
><LI
STYLE="list-style-type: disc"
><P
>Provide a standard that is attractive to the implementors of different
UNIX-like systems.</P
></LI
></UL
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="SCOPE"
>Scope</A
></H2
><P
>This document specifies a standard filesystem hierarchy for FHS
filesystems by specifying the location of files and directories, and
the contents of some system files.</P
><P
>This standard has been designed to be used by system
integrators, package developers, and system administrators in the
construction and maintenance of FHS compliant filesystems.  It is
primarily intended to be a reference and is not a tutorial on how to
manage a conforming filesystem hierarchy.</P
><P
>The FHS grew out of earlier work on FSSTND, a filesystem
organization standard for the Linux operating system.  It builds on
FSSTND to address interoperability issues not just in the Linux
community but in a wider arena including 4.4BSD-based operating
systems.  It incorporates lessons learned in the BSD world and
elsewhere about multi-architecture support and the demands of
heterogeneous networking.</P
><P
>Although this standard is more comprehensive than previous
attempts at filesystem hierarchy standardization, periodic updates may
become necessary as requirements change in relation to emerging
technology.  It is also possible that better solutions to the problems
addressed here will be discovered so that our solutions will no longer
be the best possible solutions.  Supplementary drafts may be released
in addition to periodic updates to this document.  However, a specific
goal is backwards compatibility from one release of this document to
the next.</P
><P
>Comments related to this standard are welcome.  Any comments or
suggestions for changes may be directed to the FHS editor (Daniel
Quinlan &lt;quinlan@pathname.com&gt;) or the FHS mailing list.
Typographical or grammatical comments should be directed to the FHS
editor.</P
><P
>Before sending mail to the mailing list it is requested that you
first contact the FHS editor in order to avoid excessive re-discussion
of old topics.</P
><P
>Questions about how to interpret items in this document may
occasionally arise.  If you have need for a clarification, please
contact the FHS editor.  Since this standard represents a consensus of
many participants, it is important to make certain that any
interpretation also represents their collective opinion.  For this
reason it may not be possible to provide an immediate response unless
the inquiry has been the subject of previous discussion.</P
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="ACKNOWLEDGMENTS"
>Acknowledgments</A
></H2
><P
>The developers of the FHS wish to thank the developers, system
administrators, and users whose input was essential to this standard.
We wish to thank each of the contributors who helped to write,
compile, and compose this standard.</P
><P
>The FHS Group also wishes to thank those Linux developers who
supported the FSSTND, the predecessor to this standard.  If they
hadn't demonstrated that the FSSTND was beneficial, the FHS could
never have evolved.</P
></DIV
><DIV
CLASS="SECTION"
><HR><H2
CLASS="SECTION"
><A
NAME="CONTRIBUTORS"
>Contributors</A
></H2
><DIV
CLASS="INFORMALTABLE"
><P
></P
><A
NAME="AEN2813"
></A
><TABLE
BORDER="0"
FRAME="void"
CLASS="CALSTABLE"
><COL
WIDTH="1*"
TITLE="C1"><COL
WIDTH="1*"
TITLE="C2"><TBODY
><TR
><TD
ALIGN="LEFT"
>Brandon S. Allbery</TD
><TD
ALIGN="LEFT"
>&lt;bsa@kf8nh.wariat.org&gt;</TD
></TR
><TR
><TD
ALIGN="LEFT"
>Keith Bostic</TD
><TD
ALIGN="LEFT"
>&lt;bostic@cs.berkeley.edu&gt;</TD
></TR
><TR
><TD
ALIGN="LEFT"
>Drew Eckhardt</TD
><TD
ALIGN="LEFT"
>&lt;drew@colorado.edu&gt;</TD
></TR
><TR
><TD
ALIGN="LEFT"
>Rik Faith</TD
><TD
ALIGN="LEFT"
>&lt;faith@cs.unc.edu&gt;</TD
></TR
><TR
><TD
ALIGN="LEFT"
>Stephen Harris</TD
><TD
ALIGN="LEFT"
>&lt;sweh@spuddy.mew.co.uk&gt;</TD
></TR
><TR
><TD
ALIGN="LEFT"
>Ian Jackson</TD
><TD
ALIGN="LEFT"
>&lt;ijackson@cus.cam.ac.uk&gt;</TD
></TR
><TR
><TD
ALIGN="LEFT"
>Andreas Jaeger</TD
><TD
ALIGN="LEFT"
>&lt;aj@suse.de&gt;</TD
></TR
><TR
><TD
ALIGN="LEFT"
>John A. Martin</TD
><TD
ALIGN="LEFT"
>&lt;jmartin@acm.org&gt;</TD
></TR
><TR
><TD
ALIGN="LEFT"
>Ian McCloghrie</TD
><TD
ALIGN="LEFT"
>&lt;ian@ucsd.edu&gt;</TD
></TR
><TR
><TD
ALIGN="LEFT"
>Chris Metcalf</TD
><TD
ALIGN="LEFT"
>&lt;metcalf@lcs.mit.edu&gt;</TD
></TR
><TR
><TD
ALIGN="LEFT"
>Ian Murdock</TD
><TD
ALIGN="LEFT"
>&lt;imurdock@debian.org&gt;</TD
></TR
><TR
><TD
ALIGN="LEFT"
>David C. Niemi</TD
><TD
ALIGN="LEFT"
>&lt;niemidc@clark.net&gt;</TD
></TR
><TR
><TD
ALIGN="LEFT"
>Daniel Quinlan</TD
><TD
ALIGN="LEFT"
>&lt;quinlan@pathname.com&gt;</TD
></TR
><TR
><TD
ALIGN="LEFT"
>Eric S. Raymond</TD
><TD
ALIGN="LEFT"
>&lt;esr@thyrsus.com&gt;</TD
></TR
><TR
><TD
ALIGN="LEFT"
>Rusty Russell</TD
><TD
ALIGN="LEFT"
>&lt;rusty@rustcorp.com.au&gt;</TD
></TR
><TR
><TD
ALIGN="LEFT"
>Mike Sangrey</TD
><TD
ALIGN="LEFT"
>&lt;mike@sojurn.lns.pa.us&gt;</TD
></TR
><TR
><TD
ALIGN="LEFT"
>David H. Silber</TD
><TD
ALIGN="LEFT"
>&lt;dhs@glowworm.firefly.com&gt;</TD
></TR
><TR
><TD
ALIGN="LEFT"
>Thomas Sippel-Dau</TD
><TD
ALIGN="LEFT"
>&lt;t.sippel-dau@ic.ac.uk&gt;</TD
></TR
><TR
><TD
ALIGN="LEFT"
>Theodore Ts'o</TD
><TD
ALIGN="LEFT"
>&lt;tytso@athena.mit.edu&gt;</TD
></TR
><TR
><TD
ALIGN="LEFT"
>Stephen Tweedie</TD
><TD
ALIGN="LEFT"
>&lt;sct@dcs.ed.ac.uk&gt;</TD
></TR
><TR
><TD
ALIGN="LEFT"
>Fred N. van Kempen</TD
><TD
ALIGN="LEFT"
>&lt;waltje@infomagic.com&gt;</TD
></TR
><TR
><TD
ALIGN="LEFT"
>Bernd Warken</TD
><TD
ALIGN="LEFT"
>&lt;bwarken@mayn.de&gt;</TD
></TR
><TR
><TD
ALIGN="LEFT"
>Christopher Yeoh</TD
><TD
ALIGN="LEFT"
>&lt;cyeoh@samba.org&gt;</TD
></TR
></TBODY
></TABLE
><P
></P
></DIV
></DIV
></DIV
></DIV
><H3
CLASS="FOOTNOTES"
>Notes</H3
><TABLE
BORDER="0"
CLASS="FOOTNOTES"
WIDTH="100%"
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN261"
HREF="#AEN261"
><SPAN
CLASS="footnote"
>[1]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
>Command binaries that are not essential enough to place into
<TT
CLASS="FILENAME"
>/bin</TT
> must be placed in
<TT
CLASS="FILENAME"
>/usr/bin</TT
>, instead.  Items that are required only
by non-root users (the X Window System, <TT
CLASS="FILENAME"
>chsh</TT
>,
etc.) are generally not essential enough to be placed into the root
partition.</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN493"
HREF="#AEN493"
><SPAN
CLASS="footnote"
>[2]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
> Programs necessary to arrange for the boot loader to be
able to boot a file must be placed in <TT
CLASS="FILENAME"
>/sbin</TT
>.
Configuration files for boot loaders must be placed in
<TT
CLASS="FILENAME"
>/etc</TT
>.</P
><P
>The GRUB bootloader reads its configurations file before
booting, so that must be placed in <TT
CLASS="FILENAME"
>/boot</TT
>.  However, it is a
configuration file, so should be in <TT
CLASS="FILENAME"
>/etc</TT
>.  The answer here is a
symbolic link such as <TT
CLASS="FILENAME"
>/etc/grub/menu.lst</TT
> -&#62; <TT
CLASS="FILENAME"
>/boot/menu.lst</TT
>.</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN507"
HREF="#AEN507"
><SPAN
CLASS="footnote"
>[3]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
>On some i386 machines, it may be necessary for
<TT
CLASS="FILENAME"
>/boot</TT
> to be located on a separate partition
located completely below cylinder 1024 of the boot device due to
hardware constraints.</P
><P
>Certain MIPS systems require a <TT
CLASS="FILENAME"
>/boot</TT
>
partition that is a mounted MS-DOS filesystem or whatever other
filesystem type is accessible for the firmware.  This may result in
restrictions with respect to usable filenames within
<TT
CLASS="FILENAME"
>/boot</TT
> (only for affected systems).</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN534"
HREF="#AEN534"
><SPAN
CLASS="footnote"
>[4]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
>The setup of command scripts invoked at boot time may resemble System
V, BSD or other models.  Further specification in this area may be
added to a future version of this standard.</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN540"
HREF="#AEN540"
><SPAN
CLASS="footnote"
>[5]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
>It is recommended that files be stored in subdirectories of
<TT
CLASS="FILENAME"
>/etc</TT
> rather than directly in
<TT
CLASS="FILENAME"
>/etc</TT
>.</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN581"
HREF="#AEN581"
><SPAN
CLASS="footnote"
>[6]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
>Systems that use the shadow password suite will have additional
configuration files in <TT
CLASS="FILENAME"
>/etc</TT
>
(<TT
CLASS="FILENAME"
>/etc/shadow</TT
> and others) and programs in
<TT
CLASS="FILENAME"
>/usr/sbin</TT
> (<B
CLASS="COMMAND"
>useradd</B
>,
<B
CLASS="COMMAND"
>usermod</B
>, and others).</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN722"
HREF="#AEN722"
><SPAN
CLASS="footnote"
>[7]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
>On some Linux systems, this may be a symbolic link to
<TT
CLASS="FILENAME"
>/proc/mounts</TT
>, in which case this exception is not
required.</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN778"
HREF="#AEN778"
><SPAN
CLASS="footnote"
>[8]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
><TT
CLASS="FILENAME"
>/etc/X11/xdm</TT
> holds the configuration files for
<TT
CLASS="FILENAME"
>xdm</TT
>.  These are most of the files previously
found in <TT
CLASS="FILENAME"
>/usr/lib/X11/xdm</TT
>.  Some local variable
data for <TT
CLASS="FILENAME"
>xdm</TT
> is stored in
<TT
CLASS="FILENAME"
>/var/lib/xdm</TT
>.</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN808"
HREF="#AEN808"
><SPAN
CLASS="footnote"
>[9]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
>Different people prefer to place user accounts in a variety of places.
This section describes only a suggested placement for user home
directories; nevertheless we recommend that all FHS-compliant
distributions use this as the default location for home
directories.</P
><P
>On small systems, each user's directory is typically one of the
many subdirectories of <TT
CLASS="FILENAME"
>/home</TT
> such as
<TT
CLASS="FILENAME"
>/home/smith</TT
>, <TT
CLASS="FILENAME"
>/home/torvalds</TT
>,
<TT
CLASS="FILENAME"
>/home/operator</TT
>, etc.  On large systems
(especially when the <TT
CLASS="FILENAME"
>/home</TT
> directories are shared
amongst many hosts using NFS) it is useful to subdivide user home
directories.  Subdivision may be accomplished by using subdirectories
such as <TT
CLASS="FILENAME"
>/home/staff</TT
>,
<TT
CLASS="FILENAME"
>/home/guests</TT
>,
<TT
CLASS="FILENAME"
>/home/students</TT
>, etc.</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN819"
HREF="#AEN819"
><SPAN
CLASS="footnote"
>[10]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
>If you want to find out a user's home directory, you should use the
<TT
CLASS="FILENAME"
>getpwent(3)</TT
> library function rather than relying
on <TT
CLASS="FILENAME"
>/etc/passwd</TT
> because user information may be
stored remotely using systems such as NIS.</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN826"
HREF="#AEN826"
><SPAN
CLASS="footnote"
>[11]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
>It is recommended that apart from autosave and lock files programs
should refrain from creating non dot files or directories in a home
directory without user intervention.</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN836"
HREF="#AEN836"
><SPAN
CLASS="footnote"
>[12]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
>Shared libraries that are only necessary for binaries in
<TT
CLASS="FILENAME"
>/usr</TT
> (such as any X Window binaries) must not be
in <TT
CLASS="FILENAME"
>/lib</TT
>. Only the shared libraries required to
run binaries in <TT
CLASS="FILENAME"
>/bin</TT
> and
<TT
CLASS="FILENAME"
>/sbin</TT
> may be here.  In particular, the library
<TT
CLASS="FILENAME"
>libm.so.*</TT
> may also be placed in
<TT
CLASS="FILENAME"
>/usr/lib</TT
> if it is not required by anything in
<TT
CLASS="FILENAME"
>/bin</TT
> or <TT
CLASS="FILENAME"
>/sbin</TT
>.</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN866"
HREF="#AEN866"
><SPAN
CLASS="footnote"
>[13]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
>The usual placement of this binary is <TT
CLASS="FILENAME"
>/usr/bin/cpp</TT
>.</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN890"
HREF="#AEN890"
><SPAN
CLASS="footnote"
>[14]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
>This is commonly used for 64-bit or 32-bit support on
systems which support multiple binary formats, but require libraries
of the same name.  In this case, <TT
CLASS="FILENAME"
>/lib32</TT
> and
<TT
CLASS="FILENAME"
>/lib64</TT
> might be the library directories, and
<TT
CLASS="FILENAME"
>/lib</TT
> a symlink to one of them.</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN900"
HREF="#AEN900"
><SPAN
CLASS="footnote"
>[15]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
><TT
CLASS="FILENAME"
>/lib&lt;qual&gt;/cpp</TT
> is still permitted: this
allows the case where <TT
CLASS="FILENAME"
>/lib</TT
> and
<TT
CLASS="FILENAME"
>/lib&lt;qual&gt;</TT
> are the same (one is a symbolic
link to the other). </P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN947"
HREF="#AEN947"
><SPAN
CLASS="footnote"
>[16]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
>A compliant implementation with two CDROM drives might have
<TT
CLASS="FILENAME"
>/media/cdrom0</TT
> and
<TT
CLASS="FILENAME"
>/media/cdrom1</TT
> with
<TT
CLASS="FILENAME"
>/media/cdrom</TT
> a symlink to either of these.</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN1037"
HREF="#AEN1037"
><SPAN
CLASS="footnote"
>[17]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
>If the home directory of the root account is not
stored on the root partition it will be necessary to make certain it
will default to <TT
CLASS="FILENAME"
>/</TT
> if it can not be
located.</P
><P
>We recommend against using the root account for tasks that can be
performed as an unprivileged user, and that it be used solely for system
administration.  For this reason, we recommend that subdirectories for
mail and other applications not appear in the root account's home
directory, and that mail for administration roles such as root,
postmaster, and webmaster be forwarded to an appropriate user.</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN1051"
HREF="#AEN1051"
><SPAN
CLASS="footnote"
>[18]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
>Originally, <TT
CLASS="FILENAME"
>/sbin</TT
> binaries were kept in
<TT
CLASS="FILENAME"
>/etc</TT
>.  </P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN1058"
HREF="#AEN1058"
><SPAN
CLASS="footnote"
>[19]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
>Deciding what things go into
<SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>"sbin"</I
></SPAN
> directories is simple: if a normal (not a
system administrator) user will ever run it directly, then it must be
placed in one of the <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>"bin"</I
></SPAN
> directories.  Ordinary
users should not have to place any of the <TT
CLASS="FILENAME"
>sbin</TT
>
directories in their path.</P
><P
>For example, files such as <B
CLASS="COMMAND"
>chfn</B
> which users
only occasionally use must still be placed in
<TT
CLASS="FILENAME"
>/usr/bin</TT
>.  <B
CLASS="COMMAND"
>ping</B
>, although it
is absolutely necessary for root (network recovery and diagnosis) is
often used by users and must live in <TT
CLASS="FILENAME"
>/bin</TT
> for
that reason.</P
><P
>We recommend that users have read and execute permission for
everything in <TT
CLASS="FILENAME"
>/sbin</TT
> except, perhaps, certain
setuid and setgid programs.  The division between
<TT
CLASS="FILENAME"
>/bin</TT
> and <TT
CLASS="FILENAME"
>/sbin</TT
> was not
created for security reasons or to prevent users from seeing the
operating system, but to provide a good partition between binaries
that everyone uses and ones that are primarily used for administration
tasks.  There is no inherent security advantage in making
<TT
CLASS="FILENAME"
>/sbin</TT
> off-limits for users.&#13;</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN1192"
HREF="#AEN1192"
><SPAN
CLASS="footnote"
>[20]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
>This is particularly important as these areas will often contain both
files initially installed by the distributor, and those added by the
administrator.</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN1299"
HREF="#AEN1299"
><SPAN
CLASS="footnote"
>[21]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
>Examples of such configuration files include
<TT
CLASS="FILENAME"
>Xconfig</TT
>, <TT
CLASS="FILENAME"
>XF86Config</TT
>, or
<TT
CLASS="FILENAME"
>system.twmrc</TT
>)</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN1389"
HREF="#AEN1389"
><SPAN
CLASS="footnote"
>[22]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
> Miscellaneous
architecture-independent application-specific static files and
subdirectories must be placed in <TT
CLASS="FILENAME"
>/usr/share</TT
>.</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN1394"
HREF="#AEN1394"
><SPAN
CLASS="footnote"
>[23]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
> For example, the <TT
CLASS="FILENAME"
>perl5</TT
> subdirectory for
Perl 5 modules and libraries.</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN1402"
HREF="#AEN1402"
><SPAN
CLASS="footnote"
>[24]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
>Some executable commands such as <B
CLASS="COMMAND"
>makewhatis</B
> and
<B
CLASS="COMMAND"
>sendmail</B
> have also been traditionally placed in
<TT
CLASS="FILENAME"
>/usr/lib</TT
>.  <B
CLASS="COMMAND"
>makewhatis</B
> is an
internal binary and must be placed in a binary directory; users access
only <B
CLASS="COMMAND"
>catman</B
>.  Newer <B
CLASS="COMMAND"
>sendmail</B
>
binaries are now placed by default in <TT
CLASS="FILENAME"
>/usr/sbin</TT
>.
Additionally, systems using a <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>sendmail</I
></SPAN
>-compatible
mail transfer agent must provide
<B
CLASS="COMMAND"
>/usr/sbin/sendmail</B
> as a symbolic link to the
appropriate executable. </P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN1418"
HREF="#AEN1418"
><SPAN
CLASS="footnote"
>[25]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
>Host-specific data for the X Window System must not be stored in
<TT
CLASS="FILENAME"
>/usr/lib/X11</TT
>.  Host-specific configuration files
such as <TT
CLASS="FILENAME"
>Xconfig</TT
> or
<TT
CLASS="FILENAME"
>XF86Config</TT
> must be stored in
<TT
CLASS="FILENAME"
>/etc/X11</TT
>.  This includes configuration data such
as <TT
CLASS="FILENAME"
>system.twmrc</TT
> even if it is only made a
symbolic link to a more global configuration file (probably in
<TT
CLASS="FILENAME"
>/usr/X11R6/lib/X11</TT
>).</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN1435"
HREF="#AEN1435"
><SPAN
CLASS="footnote"
>[26]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
>The case where <TT
CLASS="FILENAME"
>/usr/lib</TT
> and <TT
CLASS="FILENAME"
>/usr/lib&lt;qual&gt;</TT
> are the
same (one is a symbolic link to the other) these files and the
per-application subdirectories will exist.</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN1450"
HREF="#AEN1450"
><SPAN
CLASS="footnote"
>[27]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
>Software placed in <TT
CLASS="FILENAME"
>/</TT
> or
<TT
CLASS="FILENAME"
>/usr</TT
> may be overwritten by system upgrades
(though we recommend that distributions do not overwrite data in
<TT
CLASS="FILENAME"
>/etc</TT
> under these circumstances).  For this
reason, local software must not be placed outside of
<TT
CLASS="FILENAME"
>/usr/local</TT
> without good reason.</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN1530"
HREF="#AEN1530"
><SPAN
CLASS="footnote"
>[28]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
><TT
CLASS="FILENAME"
>/usr/local/man</TT
> may be deprecated in future FHS
releases, so if all else is equal, making that one a symlink seems
sensible.</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN1540"
HREF="#AEN1540"
><SPAN
CLASS="footnote"
>[29]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
>Locally installed system administration programs should be placed in
<TT
CLASS="FILENAME"
>/usr/local/sbin</TT
>.</P
><P
></P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN1550"
HREF="#AEN1550"
><SPAN
CLASS="footnote"
>[30]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
>Much of this data originally lived in <TT
CLASS="FILENAME"
>/usr</TT
>
(<TT
CLASS="FILENAME"
>man</TT
>, <TT
CLASS="FILENAME"
>doc</TT
>) or
<TT
CLASS="FILENAME"
>/usr/lib</TT
> (<TT
CLASS="FILENAME"
>dict</TT
>,
<TT
CLASS="FILENAME"
>terminfo</TT
>, <TT
CLASS="FILENAME"
>zoneinfo</TT
>).</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN1701"
HREF="#AEN1701"
><SPAN
CLASS="footnote"
>[31]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
>Obviously, there are no manual pages in <TT
CLASS="FILENAME"
>/</TT
>
because they are not required at boot time nor are they required in
emergencies. Really.</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN1741"
HREF="#AEN1741"
><SPAN
CLASS="footnote"
>[32]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
>For example, if <TT
CLASS="FILENAME"
>/usr/local/man</TT
>
has no manual pages in section 4 (Devices), then
<TT
CLASS="FILENAME"
>/usr/local/man/man4</TT
> may be omitted.</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN1797"
HREF="#AEN1797"
><SPAN
CLASS="footnote"
>[33]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
> A major exception to this rule is the
United Kingdom, which is `GB' in the ISO 3166, but `UK' for most email
addresses.</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN1944"
HREF="#AEN1944"
><SPAN
CLASS="footnote"
>[34]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
>Some such files include:


<TT
[44] NIS should not be confused with Sun NIS+, which uses a different
CLASS="FILENAME"
    directory, /var/nis.
>airport</TT
>, <TT
CLASS="FILENAME"
> birthtoken</TT
>, <TT
CLASS="FILENAME"
>eqnchar</TT
>, <TT
CLASS="FILENAME"
> getopt</TT
>, <TT
CLASS="FILENAME"
>gprof.callg</TT
>, <TT
CLASS="FILENAME"
> gprof.flat</TT
>, <TT
CLASS="FILENAME"
>inter.phone</TT
>, <TT
CLASS="FILENAME"
> ipfw.samp.filters</TT
>,
<TT
CLASS="FILENAME"
> ipfw.samp.scripts</TT
>, <TT
CLASS="FILENAME"
>keycap.pcvt</TT
>, <TT
CLASS="FILENAME"
> mail.help</TT
>, <TT
CLASS="FILENAME"
>mail.tildehelp</TT
>, <TT
CLASS="FILENAME"
> man.template</TT
>,
<TT
CLASS="FILENAME"
>map3270</TT
>, <TT
CLASS="FILENAME"
> mdoc.template</TT
>,
<TT
CLASS="FILENAME"
>more.help</TT
>, <TT
CLASS="FILENAME"
> na.phone</TT
>,
<TT
CLASS="FILENAME"
>nslookup.help</TT
>, <TT
CLASS="FILENAME"
> operator</TT
>,
<TT
CLASS="FILENAME"
>scsi_modes</TT
>, <TT
CLASS="FILENAME"
> sendmail.hf</TT
>,
<TT
CLASS="FILENAME"
>style</TT
>, <TT
CLASS="FILENAME"
> units.lib</TT
>,
<TT
CLASS="FILENAME"
>vgrindefs</TT
>, <TT
CLASS="FILENAME"
> vgrindefs.db</TT
>,
<TT
CLASS="FILENAME"
>zipcodes</TT
>&#13;</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN2042"
HREF="#AEN2042"
><SPAN
CLASS="footnote"
>[35]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
>Generally, source should not be built within this hierarchy.</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN2209"
HREF="#AEN2209"
><SPAN
CLASS="footnote"
>[36]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
>This standard does not currently incorporate the TeX Directory
Structure (a document that describes the layout TeX files and
directories), but it may be useful reading.  It is located at
<A
HREF="ftp://ctan.tug.org/tex/"
TARGET="_top"
>ftp://ctan.tug.org/tex/</A
></P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN2244"
HREF="#AEN2244"
><SPAN
CLASS="footnote"
>[37]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
>For example, <TT
CLASS="FILENAME"
>/usr/share/man/man1/ls.1</TT
> is
formatted into <TT
CLASS="FILENAME"
>/var/cache/man/cat1/ls.1</TT
>, and
<TT
CLASS="FILENAME"
>/usr/X11R6/man/&lt;locale&gt;/man3/XtClass.3x</TT
> into
<TT
CLASS="FILENAME"
>/var/cache/man/X11R6/&lt;locale&gt;/cat3/XtClass.3x</TT
>.</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN2295"
HREF="#AEN2295"
><SPAN
CLASS="footnote"
>[38]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
>An important difference between this version of this standard and
previous ones is that applications are now required to use a
subdirectory of <TT
CLASS="FILENAME"
>/var/lib</TT
>.  </P
><P
></P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN2381"
HREF="#AEN2381"
><SPAN
CLASS="footnote"
>[39]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
>This hierarchy should contain files stored in
<TT
CLASS="FILENAME"
>/var/db</TT
> in current BSD releases.  These include
<TT
CLASS="FILENAME"
>locate.database</TT
> and
<TT
CLASS="FILENAME"
>mountdtab</TT
>, and the kernel symbol database(s).</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN2396"
HREF="#AEN2396"
><SPAN
CLASS="footnote"
>[40]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
>Then, anything wishing to use <TT
CLASS="FILENAME"
>/dev/ttyS0</TT
>
can read the lock file and act accordingly (all locks in
<TT
CLASS="FILENAME"
>/var/lock</TT
> should be world-readable).</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN2437"
HREF="#AEN2437"
><SPAN
CLASS="footnote"
>[41]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
>Note that <TT
CLASS="FILENAME"
>/var/mail</TT
> may be a symbolic link to
another directory.</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN2469"
HREF="#AEN2469"
><SPAN
CLASS="footnote"
>[42]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
><TT
CLASS="FILENAME"
>/var/run</TT
> should be unwritable for unprivileged
users (root or users running daemons); it is a major security problem
if any user can write in this directory.</P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN2493"
HREF="#AEN2493"
><SPAN
CLASS="footnote"
>[43]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
>UUCP lock files must be placed in <TT
CLASS="FILENAME"
>/var/lock</TT
>.  See
the above section on <TT
CLASS="FILENAME"
>/var/lock</TT
>.  </P
></TD
></TR
><TR
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="5%"
><A
NAME="FTN.AEN2582"
HREF="#AEN2582"
><SPAN
CLASS="footnote"
>[44]</SPAN
></A
></TD
><TD
ALIGN="LEFT"
VALIGN="TOP"
WIDTH="95%"
><P
>NIS should not be confused with Sun NIS+, which uses a different
directory, <TT
CLASS="FILENAME"
>/var/nis</TT
>.</P
></TD
></TR
></TABLE
></BODY
></HTML
>

Revision as of 03:47, 13 November 2008

Filesystem Hierarchy Standard

Filesystem Hierarchy Standard Group

Edited by

Rusty Russell

Daniel Quinlan

Christopher Yeoh

Copyright © 1994-2004 Daniel Quinlan

Copyright © 2001-2004 Paul 'Rusty' Russell

Copyright © 2003-2004 Christopher Yeoh

This standard consists of a set of requirements and guidelines for file and directory placement under UNIX-like operating systems. The guidelines are intended to support interoperability of applications, system administration tools, development tools, and scripts as well as greater uniformity of documentation for these systems.

All trademarks and copyrights are owned by their owners, unless specifically noted otherwise. Use of a term in this document should not be regarded as affecting the validity of any trademark or service mark.

Permission is granted to make and distribute verbatim copies of this standard provided the copyright and this permission notice are preserved on all copies.

Permission is granted to copy and distribute modified versions of this standard under the conditions for verbatim copying, provided also that the title page is labeled as modified including a reference to the original standard, provided that information on retrieving the original standard is included, and provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one.

Permission is granted to copy and distribute translations of this standard into another language, under the above conditions for modified versions, except that this permission notice may be stated in a translation approved by the copyright holder.

Here is the home of the Filesystem Hierarchy Standard (FHS). The copy you are reading is version 2.3. It was announced on January 29, 2004. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

Table of Contents 1. Introduction 

   Purpose
   Conventions

2. The Filesystem 3. The Root Filesystem 

   Purpose
   Requirements
   Specific Options
   /bin : Essential user command binaries (for use by all users)

       Purpose
       Requirements
       Specific Options

   /boot : Static files of the boot loader

       Purpose
       Specific Options

   /dev : Device files

       Purpose
       Specific Options

   /etc : Host-specific system configuration

       Purpose
       Requirements
       Specific Options
       /etc/opt : Configuration files for /opt
       /etc/X11 : Configuration for the X Window System (optional)
       /etc/sgml : Configuration files for SGML (optional)
       /etc/xml : Configuration files for XML (optional)

   /home : User home directories (optional)

       Purpose
       Requirements

   /lib : Essential shared libraries and kernel modules

       Purpose
       Requirements
       Specific Options

   /lib<qual> : Alternate format essential shared libraries (optional)

       Purpose
       Requirements

   /media : Mount point for removeable media

       Purpose
       Specific Options

   /mnt : Mount point for a temporarily mounted filesystem

       Purpose

   /opt : Add-on application software packages

       Purpose
       Requirements

   /root : Home directory for the root user (optional)

       Purpose

   /sbin : System binaries

       Purpose
       Requirements
       Specific Options

   /srv : Data for services provided by this system

       Purpose

   /tmp : Temporary files

       Purpose

4. The /usr Hierarchy 

   Purpose
   Requirements
   Specific Options
   /usr/X11R6 : X Window System, Version 11 Release 6 (optional)

       Purpose
       Specific Options

   /usr/bin : Most user commands

       Purpose
       Specific Options

   /usr/include : Directory for standard include files.

       Purpose
       Specific Options

   /usr/lib : Libraries for programming and packages

       Purpose
       Specific Options

   /usr/lib<qual> : Alternate format libraries (optional)

       Purpose
       /usr/local : Local hierarchy

   /usr/local/share
   /usr/sbin : Non-essential standard system binaries

       Purpose

   /usr/share : Architecture-independent data

       Purpose
       Requirements
       Specific Options
       /usr/share/dict : Word lists (optional)
       /usr/share/man : Manual pages
       /usr/share/misc : Miscellaneous architecture-independent data
       /usr/share/sgml : SGML data (optional)
       /usr/share/xml : XML data (optional)

   /usr/src : Source code (optional)

       Purpose

5. The /var Hierarchy 

   Purpose
   Requirements
   Specific Options
   /var/account : Process accounting logs (optional)

       Purpose

   /var/cache : Application cache data

       Purpose
       Specific Options
       /var/cache/fonts : Locally-generated fonts (optional)
       /var/cache/man : Locally-formatted manual pages (optional)

   /var/crash : System crash dumps (optional)

       Purpose

   /var/games : Variable game data (optional)

       Purpose

   /var/lib : Variable state information

       Purpose
       Requirements
       Specific Options
       /var/lib/<editor> : Editor backup files and state (optional)
       /var/lib/hwclock : State directory for hwclock (optional)
       /var/lib/misc : Miscellaneous variable data

   /var/lock : Lock files

       Purpose

   /var/log : Log files and directories

       Purpose
       Specific Options

   /var/mail : User mailbox files (optional)

       Purpose

   /var/opt : Variable data for /opt

       Purpose

   /var/run : Run-time variable data

       Purpose
       Requirements

   /var/spool : Application spool data

       Purpose
       Specific Options
       /var/spool/lpd : Line-printer daemon print queues (optional)
       /var/spool/rwho : Rwhod files (optional)

   /var/tmp : Temporary files preserved between system reboots

       Purpose

   /var/yp : Network Information Service (NIS) database files (optional)

       Purpose

6. Operating System Specific Annex 

   Linux

       / : Root directory
       /bin : Essential user command binaries (for use by all users)
       /dev : Devices and special files
       /etc : Host-specific system configuration
       /lib64 and /lib32 : 64/32-bit libraries (architecture dependent)
       /proc : Kernel and process information virtual filesystem
       /sbin : Essential system binaries
       /usr/include : Header files included by C programs
       /usr/src : Source code
       /var/spool/cron : cron and at jobs

7. Appendix 

   The FHS mailing list
   Background of the FHS
   General Guidelines
   Scope
   Acknowledgments
   Contributors

━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

Chapter 1. Introduction

Purpose

This standard enables: 

 • Software to predict the location of installed files and directories, and

 • Users to predict the location of installed files and directories.

We do this by: 

 • Specifying guiding principles for each area of the filesystem,

 • Specifying the minimum files and directories required,

 • Enumerating exceptions to the principles, and

 • Enumerating specific cases where there has been historical conflict.

The FHS document is used by: 

 • Independent software suppliers to create applications which are FHS
   compliant, and work with distributions which are FHS complaint,

 • OS creators to provide systems which are FHS compliant, and

 • Users to understand and maintain the FHS compliance of a system.

The FHS document has a limited scope: 

 • Local placement of local files is a local issue, so FHS does not attempt to
   usurp system administrators.

 • FHS addresses issues where file placements need to be coordinated between
   multiple parties such as local sites, distributions, applications,
   documentation, etc.

━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

Conventions

We recommend that you read a typeset version of this document rather than the plain text version. In the typeset version, the names of files and directories are displayed in a constant-width font.

Components of filenames that vary are represented by a description of the contents enclosed in "<" and ">" characters, <thus>. Electronic mail addresses are also enclosed in "<" and ">" but are shown in the usual typeface.

Optional components of filenames are enclosed in "[" and "]" characters and may be combined with the "<" and ">" convention. For example, if a filename is allowed to occur either with or without an extension, it might be represented by <filename>[.<extension>].

Variable substrings of directory names and filenames are indicated by "*".

The sections of the text marked as Rationale are explanatory and are non-normative.

━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

Chapter 2. The Filesystem

This standard assumes that the operating system underlying an FHS-compliant file system supports the same basic security features found in most UNIX filesystems.

It is possible to define two independent distinctions among files: shareable vs. unshareable and variable vs. static. In general, files that differ in either of these respects should be located in different directories. This makes it easy to store files with different usage characteristics on different filesystems.

"Shareable" files are those that can be stored on one host and used on others. "Unshareable" files are those that are not shareable. For example, the files in user home directories are shareable whereas device lock files are not.

"Static" files include binaries, libraries, documentation files and other files that do not change without system administrator intervention. "Variable" files are files that are not static. 

   Rationale: Shareable files can be stored on one host and used on several
   others. Typically, however, not all files in the filesystem hierarchy are
   shareable and so each system has local storage containing at least its
   unshareable files. It is convenient if all the files a system requires that
   are stored on a foreign host can be made available by mounting one or a few
   directories from the foreign host.

   Static and variable files should be segregated because static files, unlike
   variable files, can be stored on read-only media and do not need to be
   backed up on the same schedule as variable files.

   Historical UNIX-like filesystem hierarchies contained both static and
   variable files under both /usr and /etc. In order to realize the advantages
   mentioned above, the /var hierarchy was created and all variable files were
   transferred from /usr to /var. Consequently /usr can now be mounted
   read-only (if it is a separate filesystem). Variable files have been
   transferred from /etc to /var over a longer period as technology has
   permitted.

   Here is an example of a FHS-compliant system. (Other FHS-compliant layouts
   are possible.)

   ┌────────┬───────────────┬───────────┐
   │        │   shareable   │unshareable│
   ├────────┼───────────────┼───────────┤
   │static  │/usr           │/etc       │
   ├────────┼───────────────┼───────────┤
   │        │/opt           │/boot      │
   ├────────┼───────────────┼───────────┤
   │variable│/var/mail      │/var/run   │
   ├────────┼───────────────┼───────────┤
   │        │/var/spool/news│/var/lock  │
   └────────┴───────────────┴───────────┘

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Chapter 3. The Root Filesystem

Purpose

The contents of the root filesystem must be adequate to boot, restore, recover, and/or repair the system. 

 • To boot a system, enough must be present on the root partition to mount
   other filesystems. This includes utilities, configuration, boot loader
   information, and other essential start-up data. /usr, /opt, and /var are
   designed such that they may be located on other partitions or filesystems.

 • To enable recovery and/or repair of a system, those utilities needed by an
   experienced maintainer to diagnose and reconstruct a damaged system must be
   present on the root filesystem.

 • To restore a system, those utilities needed to restore from system backups
   (on floppy, tape, etc.) must be present on the root filesystem.

   Rationale: The primary concern used to balance these considerations, which
   favor placing many things on the root filesystem, is the goal of keeping
   root as small as reasonably possible. For several reasons, it is desirable
   to keep the root filesystem small:

     □ It is occasionally mounted from very small media.

     □ The root filesystem contains many system-specific configuration files.
       Possible examples include a kernel that is specific to the system, a
       specific hostname, etc. This means that the root filesystem isn't
       always shareable between networked systems. Keeping it small on servers
       in networked systems minimizes the amount of lost space for areas of
       unshareable files. It also allows workstations with smaller local hard
       drives.

     □ While you may have the root filesystem on a large partition, and may be
       able to fill it to your heart's content, there will be people with
       smaller partitions. If you have more files installed, you may find
       incompatibilities with other systems using root filesystems on smaller
       partitions. If you are a developer then you may be turning your
       assumption into a problem for a large number of users.

     □ Disk errors that corrupt data on the root filesystem are a greater
       problem than errors on any other partition. A small root filesystem is
       less prone to corruption as the result of a system crash.

Applications must never create or require special files or subdirectories in the root directory. Other locations in the FHS hierarchy provide more than enough flexibility for any package. 

   Rationale: There are several reasons why creating a new subdirectory of the
   root filesystem is prohibited:

     □ It demands space on a root partition which the system administrator may
       want kept small and simple for either performance or security reasons.

     □ It evades whatever discipline the system administrator may have set up
       for distributing standard file hierarchies across mountable volumes.

   Distributions should not create new directories in the root hierarchy
   without extremely careful consideration of the consequences including for
   application portability.

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Requirements

The following directories, or symbolic links to directories, are required in /.

Directory Description bin Essential command binaries boot Static files of the boot loader dev Device files etc Host-specific system configuration lib Essential shared libraries and kernel modules media Mount point for removeable media mnt Mount point for mounting a filesystem temporarily opt Add-on application software packages sbin Essential system binaries srv Data for services provided by this system tmp Temporary files usr Secondary hierarchy var Variable data

Each directory listed above is specified in detail in separate subsections below. /usr and /var each have a complete section in this document due to the complexity of those directories.

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Specific Options

The following directories, or symbolic links to directories, must be in /, if the corresponding subsystem is installed:

Directory Description home User home directories (optional) lib<qual> Alternate format essential shared libraries (optional) root Home directory for the root user (optional)

Each directory listed above is specified in detail in separate subsections below.

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/bin : Essential user command binaries (for use by all users)

Purpose

/bin contains commands that may be used by both the system administrator and by users, but which are required when no other filesystems are mounted (e.g. in single user mode). It may also contain commands which are used indirectly by scripts. [1]

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Requirements

There must be no subdirectories in /bin.

The following commands, or symbolic links to commands, are required in /bin.

Command Description cat Utility to concatenate files to standard output chgrp Utility to change file group ownership chmod Utility to change file access permissions chown Utility to change file owner and group cp Utility to copy files and directories date Utility to print or set the system data and time dd Utility to convert and copy a file df Utility to report filesystem disk space usage dmesg Utility to print or control the kernel message buffer echo Utility to display a line of text false Utility to do nothing, unsuccessfully hostname Utility to show or set the system's host name kill Utility to send signals to processes ln Utility to make links between files login Utility to begin a session on the system ls Utility to list directory contents mkdir Utility to make directories mknod Utility to make block or character special files more Utility to page through text mount Utility to mount a filesystem mv Utility to move/rename files ps Utility to report process status pwd Utility to print name of current working directory rm Utility to remove files or directories rmdir Utility to remove empty directories sed The `sed' stream editor sh The Bourne command shell stty Utility to change and print terminal line settings su Utility to change user ID sync Utility to flush filesystem buffers true Utility to do nothing, successfully umount Utility to unmount file systems uname Utility to print system information

If /bin/sh is not a true Bourne shell, it must be a hard or symbolic link to the real shell command.

The [ and test commands must be placed together in either /bin or /usr/bin. 

   Rationale: For example bash behaves differently when called as sh or bash.
   The use of a symbolic link also allows users to easily see that /bin/sh is
   not a true Bourne shell.

   The requirement for the [ and test commands to be included as binaries
   (even if implemented internally by the shell) is shared with the POSIX.2
   standard.

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Specific Options

The following programs, or symbolic links to programs, must be in /bin if the corresponding subsystem is installed:

Command Description csh The C shell (optional) ed The `ed' editor (optional) tar The tar archiving utility (optional) cpio The cpio archiving utility (optional) gzip The GNU compression utility (optional) gunzip The GNU uncompression utility (optional) zcat The GNU uncompression utility (optional) netstat The network statistics utility (optional) ping The ICMP network test utility (optional)

If the gunzip and zcat programs exist, they must be symbolic or hard links to gzip. /bin/csh may be a symbolic link to /bin/tcsh or /usr/bin/tcsh. 

   Rationale: The tar, gzip and cpio commands have been added to make
   restoration of a system possible (provided that / is intact).

   Conversely, if no restoration from the root partition is ever expected,
   then these binaries might be omitted (e.g., a ROM chip root, mounting /usr
   through NFS). If restoration of a system is planned through the network,
   then ftp or tftp (along with everything necessary to get an ftp connection)
   must be available on the root partition.

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/boot : Static files of the boot loader

Purpose

This directory contains everything required for the boot process except configuration files not needed at boot time and the map installer. Thus /boot stores data that is used before the kernel begins executing user-mode programs. This may include saved master boot sectors and sector map files. [2]

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Specific Options

The operating system kernel must be located in either / or /boot. [3]

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/dev : Device files

Purpose

The /dev directory is the location of special or device files.

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Specific Options

If it is possible that devices in /dev will need to be manually created, /dev must contain a command named MAKEDEV, which can create devices as needed. It may also contain a MAKEDEV.local for any local devices.

If required, MAKEDEV must have provisions for creating any device that may be found on the system, not just those that a particular implementation installs.

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/etc : Host-specific system configuration

Purpose

The /etc hierarchy contains configuration files. A "configuration file" is a local file used to control the operation of a program; it must be static and cannot be an executable binary. [4]

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Requirements

No binaries may be located under /etc. [5]

The following directories, or symbolic links to directories are required in / etc:

Directory Description opt Configuration for /opt X11 Configuration for the X Window system (optional) sgml Configuration for SGML (optional) xml Configuration for XML (optional)

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Specific Options

The following directories, or symbolic links to directories must be in /etc, if the corresponding subsystem is installed:

Directory Description opt Configuration for /opt

The following files, or symbolic links to files, must be in /etc if the corresponding subsystem is installed: [6] 

  File                                 Description

csh.login Systemwide initialization file for C shell logins (optional) exports NFS filesystem access control list (optional) fstab Static information about filesystems (optional) ftpusers FTP daemon user access control list (optional) gateways File which lists gateways for routed (optional) gettydefs Speed and terminal settings used by getty (optional) group User group file (optional) host.conf Resolver configuration file (optional) hosts Static information about host names (optional) hosts.allow Host access file for TCP wrappers (optional) hosts.deny Host access file for TCP wrappers (optional) hosts.equiv List of trusted hosts for rlogin, rsh, rcp (optional) hosts.lpd List of trusted hosts for lpd (optional) inetd.conf Configuration file for inetd (optional) inittab Configuration file for init (optional) issue Pre-login message and identification file (optional) ld.so.conf List of extra directories to search for shared libraries (optional) motd Post-login message of the day file (optional) mtab Dynamic information about filesystems (optional) mtools.conf Configuration file for mtools (optional) networks Static information about network names (optional) passwd The password file (optional) printcap The lpd printer capability database (optional) profile Systemwide initialization file for sh shell logins (optional) protocols IP protocol listing (optional) resolv.conf Resolver configuration file (optional) rpc RPC protocol listing (optional) securetty TTY access control for root login (optional) services Port names for network services (optional) shells Pathnames of valid login shells (optional) syslog.conf Configuration file for syslogd (optional)

mtab does not fit the static nature of /etc: it is excepted for historical reasons. [7]

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/etc/opt : Configuration files for /opt

Purpose

Host-specific configuration files for add-on application software packages must be installed within the directory /etc/opt/<subdir>, where <subdir> is the name of the subtree in /opt where the static data from that package is stored.

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Requirements

No structure is imposed on the internal arrangement of /etc/opt/<subdir>.

If a configuration file must reside in a different location in order for the package or system to function properly, it may be placed in a location other than /etc/opt/<subdir>. 

   Rationale: Refer to the rationale for /opt.

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/etc/X11 : Configuration for the X Window System (optional)

Purpose

/etc/X11 is the location for all X11 host-specific configuration. This directory is necessary to allow local control if /usr is mounted read only.

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Specific Options

The following files, or symbolic links to files, must be in /etc/X11 if the corresponding subsystem is installed: 

  File                              Description

Xconfig The configuration file for early versions of XFree86 (optional) XF86Config The configuration file for XFree86 versions 3 and 4 (optional) Xmodmap Global X11 keyboard modification file (optional)

Subdirectories of /etc/X11 may include those for xdm and for any other programs (some window managers, for example) that need them. [8] We recommend that window managers with only one configuration file which is a default .*wmrc file must name it system.*wmrc (unless there is a widely-accepted alternative name) and not use a subdirectory. Any window manager subdirectories must be identically named to the actual window manager binary.

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/etc/sgml : Configuration files for SGML (optional)

Purpose

Generic configuration files defining high-level parameters of the SGML systems are installed here. Files with names *.conf indicate generic configuration files. File with names *.cat are the DTD-specific centralized catalogs, containing references to all other catalogs needed to use the given DTD. The super catalog file catalog references all the centralized catalogs.

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/etc/xml : Configuration files for XML (optional)

Purpose

Generic configuration files defining high-level parameters of the XML systems are installed here. Files with names *.conf indicate generic configuration files. The super catalog file catalog references all the centralized catalogs.

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/home : User home directories (optional)

Purpose

/home is a fairly standard concept, but it is clearly a site-specific filesystem. [9] The setup will differ from host to host. Therefore, no program should rely on this location. [10]

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Requirements

User specific configuration files for applications are stored in the user's home directory in a file that starts with the '.' character (a "dot file"). If an application needs to create more than one dot file then they should be placed in a subdirectory with a name starting with a '.' character, (a "dot directory"). In this case the configuration files should not start with the '.' character. [11]

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/lib : Essential shared libraries and kernel modules

Purpose

The /lib directory contains those shared library images needed to boot the system and run the commands in the root filesystem, ie. by binaries in /bin and /sbin. [12]

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Requirements

At least one of each of the following filename patterns are required (they may be files, or symbolic links): 

 File                    Description

libc.so.* The dynamically-linked C library (optional) ld* The execution time linker/loader (optional)

If a C preprocessor is installed, /lib/cpp must be a reference to it, for historical reasons. [13]

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Specific Options

The following directories, or symbolic links to directories, must be in /lib, if the corresponding subsystem is installed:

Directory Description modules Loadable kernel modules (optional)

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/lib<qual> : Alternate format essential shared libraries (optional)

Purpose

There may be one or more variants of the /lib directory on systems which support more than one binary format requiring separate libraries. [14]

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Requirements

If one or more of these directories exist, the requirements for their contents are the same as the normal /lib directory, except that /lib<qual>/cpp is not required. [15]

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/media : Mount point for removeable media

Purpose

This directory contains subdirectories which are used as mount points for removeable media such as floppy disks, cdroms and zip disks. 

   Rationale: Historically there have been a number of other different places
   used to mount removeable media such as /cdrom, /mnt or /mnt/cdrom. Placing
   the mount points for all removeable media directly in the root directory
   would potentially result in a large number of extra directories in /.
   Although the use of subdirectories in /mnt as a mount point has recently
   been common, it conflicts with a much older tradition of using /mnt
   directly as a temporary mount point.

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Specific Options

The following directories, or symbolic links to directories, must be in /media, if the corresponding subsystem is installed:

Directory Description floppy Floppy drive (optional) cdrom CD-ROM drive (optional) cdrecorder CD writer (optional) zip Zip drive (optional)

On systems where more than one device exists for mounting a certain type of media, mount directories can be created by appending a digit to the name of those available above starting with '0', but the unqualified name must also exist. [16]

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/mnt : Mount point for a temporarily mounted filesystem

Purpose

This directory is provided so that the system administrator may temporarily mount a filesystem as needed. The content of this directory is a local issue and should not affect the manner in which any program is run.

This directory must not be used by installation programs: a suitable temporary directory not in use by the system must be used instead.

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/opt : Add-on application software packages

Purpose

/opt is reserved for the installation of add-on application software packages.

A package to be installed in /opt must locate its static files in a separate / opt/<package> or /opt/<provider> directory tree, where <package> is a name that describes the software package and <provider> is the provider's LANANA registered name.

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Requirements

Directory Description <package> Static package objects <provider> LANANA registered provider name

The directories /opt/bin, /opt/doc, /opt/include, /opt/info, /opt/lib, and /opt /man are reserved for local system administrator use. Packages may provide "front-end" files intended to be placed in (by linking or copying) these reserved directories by the local system administrator, but must function normally in the absence of these reserved directories.

Programs to be invoked by users must be located in the directory /opt/<package> /bin or under the /opt/<provider> hierarchy. If the package includes UNIX manual pages, they must be located in /opt/<package>/share/man or under the / opt/<provider> hierarchy, and the same substructure as /usr/share/man must be used.

Package files that are variable (change in normal operation) must be installed in /var/opt. See the section on /var/opt for more information.

Host-specific configuration files must be installed in /etc/opt. See the section on /etc for more information.

No other package files may exist outside the /opt, /var/opt, and /etc/opt hierarchies except for those package files that must reside in specific locations within the filesystem tree in order to function properly. For example, device lock files must be placed in /var/lock and devices must be located in /dev.

Distributions may install software in /opt, but must not modify or delete software installed by the local system administrator without the assent of the local system administrator. 

   Rationale: The use of /opt for add-on software is a well-established
   practice in the UNIX community. The System V Application Binary Interface
   [AT&T 1990], based on the System V Interface Definition (Third Edition),
   provides for an /opt structure very similar to the one defined here.

   The Intel Binary Compatibility Standard v. 2 (iBCS2) also provides a
   similar structure for /opt.

   Generally, all data required to support a package on a system must be
   present within /opt/<package>, including files intended to be copied into /
   etc/opt/<package> and /var/opt/<package> as well as reserved directories in
   /opt.

   The minor restrictions on distributions using /opt are necessary because
   conflicts are possible between distribution-installed and locally-installed
   software, especially in the case of fixed pathnames found in some binary
   software.

   The structure of the directories below /opt/<provider> is left up to the
   packager of the software, though it is recommended that packages are
   installed in /opt/<provider>/<package> and follow a similar structure to
   the guidelines for /opt/package. A valid reason for diverging from this
   structure is for support packages which may have files installed in /opt/
   <provider>/lib or /opt/<provider>/bin.

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/root : Home directory for the root user (optional)

Purpose

The root account's home directory may be determined by developer or local preference, but this is the recommended default location. [17]

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/sbin : System binaries

Purpose

Utilities used for system administration (and other root-only commands) are stored in /sbin, /usr/sbin, and /usr/local/sbin. /sbin contains binaries essential for booting, restoring, recovering, and/or repairing the system in addition to the binaries in /bin. [18] Programs executed after /usr is known to be mounted (when there are no problems) are generally placed into /usr/sbin. Locally-installed system administration programs should be placed into /usr/ local/sbin. [19]

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Requirements

The following commands, or symbolic links to commands, are required in /sbin.

Command Description shutdown Command to bring the system down.

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Specific Options

The following files, or symbolic links to files, must be in /sbin if the corresponding subsystem is installed:

Command Description fastboot Reboot the system without checking the disks (optional) fasthalt Stop the system without checking the disks (optional) fdisk Partition table manipulator (optional) fsck File system check and repair utility (optional) fsck.* File system check and repair utility for a specific filesystem 

        (optional)

getty The getty program (optional) halt Command to stop the system (optional) ifconfig Configure a network interface (optional) init Initial process (optional) mkfs Command to build a filesystem (optional) mkfs.* Command to build a specific filesystem (optional) mkswap Command to set up a swap area (optional) reboot Command to reboot the system (optional) route IP routing table utility (optional) swapon Enable paging and swapping (optional) swapoff Disable paging and swapping (optional) update Daemon to periodically flush filesystem buffers (optional)

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/srv : Data for services provided by this system

Purpose

/srv contains site-specific data which is served by this system. 


   Rationale: This main purpose of specifying this is so that users may find
   the location of the data files for particular service, and so that services
   which require a single tree for readonly data, writable data and scripts
   (such as cgi scripts) can be reasonably placed. Data that is only of
   interest to a specific user should go in that users' home directory.

   The methodology used to name subdirectories of /srv is unspecified as there
   is currently no consensus on how this should be done. One method for
   structuring data under /srv is by protocol, eg. ftp, rsync, www, and cvs.
   On large systems it can be useful to structure /srv by administrative
   context, such as /srv/physics/www, /srv/compsci/cvs, etc. This setup will
   differ from host to host. Therefore, no program should rely on a specific
   subdirectory structure of /srv existing or data necessarily being stored in
   /srv. However /srv should always exist on FHS compliant systems and should
   be used as the default location for such data.

   Distributions must take care not to remove locally placed files in these
   directories without administrator permission. [20]


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/tmp : Temporary files

Purpose

The /tmp directory must be made available for programs that require temporary files.

Programs must not assume that any files or directories in /tmp are preserved between invocations of the program. 

   Rationale: IEEE standard P1003.2 (POSIX, part 2) makes requirements that
   are similar to the above section.

   Although data stored in /tmp may be deleted in a site-specific manner, it
   is recommended that files and directories located in /tmp be deleted
   whenever the system is booted.

   FHS added this recommendation on the basis of historical precedent and
   common practice, but did not make it a requirement because system
   administration is not within the scope of this standard.

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Chapter 4. The /usr Hierarchy

Purpose

/usr is the second major section of the filesystem. /usr is shareable, read-only data. That means that /usr should be shareable between various FHS-compliant hosts and must not be written to. Any information that is host-specific or varies with time is stored elsewhere.

Large software packages must not use a direct subdirectory under the /usr hierarchy.

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Requirements

The following directories, or symbolic links to directories, are required in / usr.

Directory Description bin Most user commands include Header files included by C programs lib Libraries local Local hierarchy (empty after main installation) sbin Non-vital system binaries share Architecture-independent data

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Specific Options

Directory Description X11R6 XWindow System, version 11 release 6 (optional) games Games and educational binaries (optional) lib<qual> Alternate Format Libraries (optional) src Source code (optional)

An exception is made for the X Window System because of considerable precedent and widely-accepted practice.

The following symbolic links to directories may be present. This possibility is based on the need to preserve compatibility with older systems until all implementations can be assumed to use the /var hierarchy. 

   /usr/spool -> /var/spool
   /usr/tmp -> /var/tmp
   /usr/spool/locks -> /var/lock

Once a system no longer requires any one of the above symbolic links, the link may be removed, if desired.

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/usr/X11R6 : X Window System, Version 11 Release 6 (optional)

Purpose

This hierarchy is reserved for the X Window System, version 11 release 6, and related files.

To simplify matters and make XFree86 more compatible with the X Window System on other systems, the following symbolic links must be present if /usr/X11R6 exists: 

   /usr/bin/X11 -> /usr/X11R6/bin
   /usr/lib/X11 -> /usr/X11R6/lib/X11
   /usr/include/X11 -> /usr/X11R6/include/X11

In general, software must not be installed or managed via the above symbolic links. They are intended for utilization by users only. The difficulty is related to the release version of the X Window System — in transitional periods, it is impossible to know what release of X11 is in use.

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Specific Options

Host-specific data in /usr/X11R6/lib/X11 should be interpreted as a demonstration file. Applications requiring information about the current host must reference a configuration file in /etc/X11, which may be linked to a file in /usr/X11R6/lib. [21]

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/usr/bin : Most user commands

Purpose

This is the primary directory of executable commands on the system.

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Specific Options

The following directories, or symbolic links to directories, must be in /usr/ bin, if the corresponding subsystem is installed:

Directory Description mh Commands for the MH mail handling system (optional)

/usr/bin/X11 must be a symlink to /usr/X11R6/bin if the latter exists.

The following files, or symbolic links to files, must be in /usr/bin, if the corresponding subsystem is installed:

Command Description perl The Practical Extraction and Report Language (optional) python The Python interpreted language (optional) tclsh Simple shell containing Tcl interpreter (optional) wish Simple Tcl/Tk windowing shell (optional) expect Program for interactive dialog (optional) 

   Rationale: Because shell script interpreters (invoked with #!<path> on the
   first line of a shell script) cannot rely on a path, it is advantageous to
   standardize their locations. The Bourne shell and C-shell interpreters are
   already fixed in /bin, but Perl, Python, and Tcl are often found in many
   different places. They may be symlinks to the physical location of the
   shell interpreters.

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/usr/include : Directory for standard include files.

Purpose

This is where all of the system's general-use include files for the C programming language should be placed.

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Specific Options

The following directories, or symbolic links to directories, must be in /usr/ include, if the corresponding subsystem is installed:

Directory Description bsd BSD compatibility include files (optional)

The symbolic link /usr/include/X11 must link to /usr/X11R6/include/X11 if the latter exists.

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/usr/lib : Libraries for programming and packages

Purpose

/usr/lib includes object files, libraries, and internal binaries that are not intended to be executed directly by users or shell scripts. [22]

Applications may use a single subdirectory under /usr/lib. If an application uses a subdirectory, all architecture-dependent data exclusively used by the application must be placed within that subdirectory. [23]

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Specific Options

For historical reasons, /usr/lib/sendmail must be a symbolic link to /usr/sbin/ sendmail if the latter exists. [24]

If /lib/X11 exists, /usr/lib/X11 must be a symbolic link to /lib/X11, or to whatever /lib/X11 is a symbolic link to. [25]

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/usr/lib<qual> : Alternate format libraries (optional)

Purpose

/usr/lib<qual> performs the same role as /usr/lib for an alternate binary format, except that the symbolic links /usr/lib<qual>/sendmail and /usr/lib <qual>/X11 are not required. [26]

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/usr/local : Local hierarchy

Purpose

The /usr/local hierarchy is for use by the system administrator when installing software locally. It needs to be safe from being overwritten when the system software is updated. It may be used for programs and data that are shareable amongst a group of hosts, but not found in /usr.

Locally installed software must be placed within /usr/local rather than /usr unless it is being installed to replace or upgrade software in /usr. [27]

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Requirements

The following directories, or symbolic links to directories, must be in /usr/ local

Directory Description bin Local binaries etc Host-specific system configuration for local binaries games Local game binaries include Local C header files lib Local libraries man Local online manuals sbin Local system binaries share Local architecture-independent hierarchy src Local source code

No other directories, except those listed below, may be in /usr/local after first installing a FHS-compliant system.

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Specific Options

If directories /lib<qual> or /usr/lib<qual> exist, the equivalent directories must also exist in /usr/local.

/usr/local/etc may be a symbolic link to /etc/local. 

   Rationale: The consistency of /usr/local/etc is beneficial to installers,
   and is already used in other systems. As all of /usr/local needs to be
   backed up to reproduce a system, it introduces no additional maintenance
   overhead, but a symlink to /etc/local is suitable if systems want alltheir
   configuration under one hierarchy.

   Note that /usr/etc is still not allowed: programs in /usr should place
   configuration files in /etc.

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/usr/local/share

The requirements for the contents of this directory are the same as /usr/share. The only additional constraint is that /usr/local/share/man and /usr/local/man directories must be synonomous (usually this means that one of them must be a symbolic link). [28]

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/usr/sbin : Non-essential standard system binaries

Purpose

This directory contains any non-essential binaries used exclusively by the system administrator. System administration programs that are required for system repair, system recovery, mounting /usr, or other essential functions must be placed in /sbin instead. [29]

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/usr/share : Architecture-independent data

Purpose

The /usr/share hierarchy is for all read-only architecture independent data files. [30]

This hierarchy is intended to be shareable among all architecture platforms of a given OS; thus, for example, a site with i386, Alpha, and PPC platforms might maintain a single /usr/share directory that is centrally-mounted. Note, however, that /usr/share is generally not intended to be shared by different OSes or by different releases of the same OS.

Any program or package which contains or requires data that doesn't need to be modified should store that data in /usr/share (or /usr/local/share, if installed locally). It is recommended that a subdirectory be used in /usr/share for this purpose.

Game data stored in /usr/share/games must be purely static data. Any modifiable files, such as score files, game play logs, and so forth, should be placed in / var/games.

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Requirements

The following directories, or symbolic links to directories, must be in /usr/ share

Directory Description man Online manuals misc Miscellaneous architecture-independent data

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Specific Options

The following directories, or symbolic links to directories, must be in /usr/ share, if the corresponding subsystem is installed:

Directory Description dict Word lists (optional) doc Miscellaneous documentation (optional) games Static data files for /usr/games (optional) info GNU Info system s primary directory (optional) locale Locale information (optional) nls Message catalogs for Native language support (optional) sgml SGML data (optional) terminfo Directories for terminfo database (optional) tmac troff macros not distributed with groff (optional) xml XML data (optional) zoneinfo Timezone information and configuration (optional)

It is recommended that application-specific, architecture-independent directories be placed here. Such directories include groff, perl, ghostscript, texmf, and kbd (Linux) or syscons (BSD). They may, however, be placed in /usr/ lib for backwards compatibility, at the distributor's discretion. Similarly, a /usr/lib/games hierarchy may be used in addition to the /usr/share/games hierarchy if the distributor wishes to place some game data there.

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/usr/share/dict : Word lists (optional)

Purpose

This directory is the home for word lists on the system; Traditionally this directory contains only the English words file, which is used by look(1) and various spelling programs. words may use either American or British spelling. 

   Rationale: The reason that only word lists are located here is that they
   are the only files common to all spell checkers.

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Specific Options

The following files, or symbolic links to files, must be in /usr/share/dict, if the corresponding subsystem is installed:

File Description words List of English words (optional)

Sites that require both American and British spelling may link words to ­/usr/ share/dict/american-english or ­/usr/share/dict/british-english.

Word lists for other languages may be added using the English name for that language, e.g., /usr/share/dict/french, /usr/share/dict/danish, etc. These should, if possible, use an ISO 8859 character set which is appropriate for the language in question; if possible the Latin1 (ISO 8859-1) character set should be used (this is often not possible).

Other word lists must be included here, if present.

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/usr/share/man : Manual pages

Purpose

This section details the organization for manual pages throughout the system, including /usr/share/man. Also refer to the section on /var/cache/man.

The primary <mandir> of the system is /usr/share/man. /usr/share/man contains manual information for commands and data under the / and /usr filesystems. [31]

Manual pages are stored in <mandir>/<locale>/man<section>/<arch>. An explanation of <mandir>, <locale>, <section>, and <arch> is given below.

A description of each section follows: 

 • man1: User programs Manual pages that describe publicly accessible commands
   are contained in this chapter. Most program documentation that a user will
   need to use is located here.

 • man2: System calls This section describes all of the system calls (requests
   for the kernel to perform operations).

 • man3: Library functions and subroutines Section 3 describes program library
   routines that are not direct calls to kernel services. This and chapter 2
   are only really of interest to programmers.

 • man4: Special files Section 4 describes the special files, related driver
   functions, and networking support available in the system. Typically, this
   includes the device files found in /dev and the kernel interface to
   networking protocol support.

 • man5: File formats The formats for many data files are documented in the
   section 5. This includes various include files, program output files, and
   system files.

 • man6: Games This chapter documents games, demos, and generally trivial
   programs. Different people have various notions about how essential this
   is.

 • man7: Miscellaneous Manual pages that are difficult to classify are
   designated as being section 7. The troff and other text processing macro
   packages are found here.

 • man8: System administration Programs used by system administrators for
   system operation and maintenance are documented here. Some of these
   programs are also occasionally useful for normal users.

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Specific Options

The following directories, or symbolic links to directories, must be in /usr/ share/<mandir>/<locale>, unless they are empty: [32]

Directory Description man1 User programs (optional) man2 System calls (optional) man3 Library calls (optional) man4 Special files (optional) man5 File formats (optional) man6 Games (optional) man7 Miscellaneous (optional) man8 System administration (optional)

The component <section> describes the manual section.

Provisions must be made in the structure of /usr/share/man to support manual pages which are written in different (or multiple) languages. These provisions must take into account the storage and reference of these manual pages. Relevant factors include language (including geographical-based differences), and character code set.

This naming of language subdirectories of /usr/share/man is based on Appendix E of the POSIX 1003.1 standard which describes the locale identification string — the most well-accepted method to describe a cultural environment. The <locale> string is:

<language>[_<territory>][.<character-set>][,<version>]

The <language> field must be taken from ISO 639 (a code for the representation of names of languages). It must be two characters wide and specified with lowercase letters only.

The <territory> field must be the two-letter code of ISO 3166 (a specification of representations of countries), if possible. (Most people are familiar with the two-letter codes used for the country codes in email addresses.) It must be two characters wide and specified with uppercase letters only. [33]

The <character-set> field must represent the standard describing the character set. If the ­<character-set> field is just a numeric specification, the number represents the number of the international standard describing the character set. It is recommended that this be a numeric representation if possible (ISO standards, especially), not include additional punctuation symbols, and that any letters be in lowercase.

A parameter specifying a <version> of the profile may be placed after the ­ <character-set> field, delimited by a comma. This may be used to discriminate between different cultural needs; for instance, dictionary order versus a more systems-oriented collating order. This standard recommends not using the <version> field, unless it is necessary.

Systems which use a unique language and code set for all manual pages may omit the <locale> substring and store all manual pages in <mandir>. For example, systems which only have English manual pages coded with ASCII, may store manual pages (the man<section> directories) directly in /usr/share/man. (That is the traditional circumstance and arrangement, in fact.)

Countries for which there is a well-accepted standard character code set may omit the ­<character-set> field, but it is strongly recommended that it be included, especially for countries with several competing standards.

Various examples:

Language Territory Character Set Directory English — ASCII /usr/share/man/en English United Kingdom ISO 8859-15 /usr/share/man/en_GB English United States ASCII /usr/share/man/en_US French Canada ISO 8859-1 /usr/share/man/fr_CA French France ISO 8859-1 /usr/share/man/fr_FR German Germany ISO 646 /usr/share/man/de_DE.646 German Germany ISO 6937 /usr/share/man/de_DE.6937 German Germany ISO 8859-1 /usr/share/man/de_DE.88591 German Switzerland ISO 646 /usr/share/man/de_CH.646 Japanese Japan JIS /usr/share/man/ja_JP.jis Japanese Japan SJIS /usr/share/man/ja_JP.sjis Japanese Japan UJIS (or EUC-J) /usr/share/man/ja_JP.ujis

Similarly, provision must be made for manual pages which are architecture-dependent, such as documentation on device-drivers or low-level system administration commands. These must be placed under an <arch> directory in the appropriate man<section> directory; for example, a man page for the i386 ctrlaltdel(8) command might be placed in /usr/share/man/<locale>/man8/i386/ ctrlaltdel.8.

Manual pages for commands and data under /usr/local are stored in /usr/local/ man. Manual pages for X11R6 are stored in /usr/X11R6/man. It follows that all manual page hierarchies in the system must have the same structure as /usr/ share/man.

The cat page sections (cat<section>) containing formatted manual page entries are also found within subdirectories of <mandir>/<locale>, but are not required nor may they be distributed in lieu of nroff source manual pages.

The numbered sections "1" through "8" are traditionally defined. In general, the file name for manual pages located within a particular section end with . <section>.

In addition, some large sets of application-specific manual pages have an additional suffix appended to the manual page filename. For example, the MH mail handling system manual pages must have mh appended to all MH manuals. All X Window System manual pages must have an x appended to the filename.

The practice of placing various language manual pages in appropriate subdirectories of /usr/share/man also applies to the other manual page hierarchies, such as /usr/local/man and /usr/X11R6/man. (This portion of the standard also applies later in the section on the optional /var/cache/man structure.)

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/usr/share/misc : Miscellaneous architecture-independent data

This directory contains miscellaneous architecture-independent files which don't require a separate subdirectory under /usr/share.

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Specific Options

The following files, or symbolic links to files, must be in /usr/share/misc, if the corresponding subsystem is installed: 

  File                             Description

ascii ASCII character set table (optional) magic Default list of magic numbers for the file command (optional) termcap Terminal capability database (optional) termcap.db Terminal capability database (optional)

Other (application-specific) files may appear here, but a distributor may place them in /usr/lib at their discretion. [34]

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/usr/share/sgml : SGML data (optional)

Purpose

/usr/share/sgml contains architecture-independent files used by SGML applications, such as ordinary catalogs (not the centralized ones, see /etc/ sgml), DTDs, entities, or style sheets.

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Specific Options

The following directories, or symbolic links to directories, must be in /usr/ share/sgml, if the corresponding subsystem is installed:

Directory Description docbook docbook DTD (optional) tei tei DTD (optional) html html DTD (optional) mathml mathml DTD (optional)

Other files that are not specific to a given DTD may reside in their own subdirectory.

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/usr/share/xml : XML data (optional)

Purpose

/usr/share/xml contains architecture-independent files used by XML applications, such as ordinary catalogs (not the centralized ones, see /etc/ sgml), DTDs, entities, or style sheets.

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Specific Options

The following directories, or symbolic links to directories, must be in /usr/ share/xml, if the corresponding subsystem is installed:

Directory Description docbook docbook XML DTD (optional) xhtml XHTML DTD (optional) mathml MathML DTD (optional)

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/usr/src : Source code (optional)

Purpose

Source code may be place placed in this subdirectory, only for reference purposes. [35]

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Chapter 5. The /var Hierarchy

Purpose

/var contains variable data files. This includes spool directories and files, administrative and logging data, and transient and temporary files.

Some portions of /var are not shareable between different systems. For instance, /var/log, /var/lock, and /var/run. Other portions may be shared, notably /var/mail, /var/cache/man, /var/cache/fonts, and /var/spool/news.

/var is specified here in order to make it possible to mount /usr read-only. Everything that once went into /usr that is written to during system operation (as opposed to installation and software maintenance) must be in /var.

If /var cannot be made a separate partition, it is often preferable to move / var out of the root partition and into the /usr partition. (This is sometimes done to reduce the size of the root partition or when space runs low in the root partition.) However, /var must not be linked to /usr because this makes separation of /usr and /var more difficult and is likely to create a naming conflict. Instead, link /var to /usr/var.

Applications must generally not add directories to the top level of /var. Such directories should only be added if they have some system-wide implication, and in consultation with the FHS mailing list.

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Requirements

The following directories, or symbolic links to directories, are required in / var.

Directory Description cache Application cache data lib Variable state information local Variable data for /usr/local lock Lock files log Log files and directories opt Variable data for /opt run Data relevant to running processes spool Application spool data tmp Temporary files preserved between system reboots

Several directories are `reserved' in the sense that they must not be used arbitrarily by some new application, since they would conflict with historical and/or local practice. They are: 

   /var/backups
   /var/cron
   /var/msgs
   /var/preserve

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Specific Options

The following directories, or symbolic links to directories, must be in /var, if the corresponding subsystem is installed:

Directory Description account Process accounting logs (optional) crash System crash dumps (optional) games Variable game data (optional) mail User mailbox files (optional) yp Network Information Service (NIS) database files (optional)

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/var/account : Process accounting logs (optional)

Purpose

This directory holds the current active process accounting log and the composite process usage data (as used in some UNIX-like systems by lastcomm and sa).

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/var/cache : Application cache data

Purpose

/var/cache is intended for cached data from applications. Such data is locally generated as a result of time-consuming I/O or calculation. The application must be able to regenerate or restore the data. Unlike /var/spool, the cached files can be deleted without data loss. The data must remain valid between invocations of the application and rebooting the system.

Files located under /var/cache may be expired in an application specific manner, by the system administrator, or both. The application must always be able to recover from manual deletion of these files (generally because of a disk space shortage). No other requirements are made on the data format of the cache directories. 

   Rationale: The existence of a separate directory for cached data allows
   system administrators to set different disk and backup policies from other
   directories in /var.

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Specific Options

Directory Description fonts Locally-generated fonts (optional) man Locally-formatted manual pages (optional) www WWW proxy or cache data (optional) <package> Package specific cache data (optional)

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/var/cache/fonts : Locally-generated fonts (optional)

Purpose

The directory /var/cache/fonts should be used to store any dynamically-created fonts. In particular, all of the fonts which are automatically generated by mktexpk must be located in appropriately-named subdirectories of /var/cache/ fonts. [36]

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Specific Options

Other dynamically created fonts may also be placed in this tree, under appropriately-named subdirectories of /var/cache/fonts.

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/var/cache/man : Locally-formatted manual pages (optional)

Purpose

This directory provides a standard location for sites that provide a read-only /usr partition, but wish to allow caching of locally-formatted man pages. Sites that mount /usr as writable (e.g., single-user installations) may choose not to use /var/cache/man and may write formatted man pages into the cat<section> directories in /usr/share/man directly. We recommend that most sites use one of the following options instead: 

 • Preformat all manual pages alongside the unformatted versions.

 • Allow no caching of formatted man pages, and require formatting to be done
   each time a man page is brought up.

 • Allow local caching of formatted man pages in /var/cache/man.

The structure of /var/cache/man needs to reflect both the fact of multiple man page hierarchies and the possibility of multiple language support.

Given an unformatted manual page that normally appears in <path>/man/<locale>/ man<section>, the directory to place formatted man pages in is /var/cache/man/ <catpath>/<locale>/cat<section>, where <catpath> is derived from <path> by removing any leading usr and/or trailing share pathname components. (Note that the <locale> component may be missing.) [37]

Man pages written to /var/cache/man may eventually be transferred to the appropriate preformatted directories in the source man hierarchy or expired; likewise formatted man pages in the source man hierarchy may be expired if they are not accessed for a period of time.

If preformatted manual pages come with a system on read-only media (a CD-ROM, for instance), they must be installed in the source man hierarchy (e.g. /usr/ share/man/cat<section>). /var/cache/man is reserved as a writable cache for formatted manual pages. 

   Rationale: Release 1.2 of the standard specified /var/catman for this
   hierarchy. The path has been moved under /var/cache to better reflect the
   dynamic nature of the formatted man pages. The directory name has been
   changed to man to allow for enhancing the hierarchy to include
   post-processed formats other than "cat", such as PostScript, HTML, or DVI.

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/var/crash : System crash dumps (optional)

Purpose

This directory holds system crash dumps. As of the date of this release of the standard, system crash dumps were not supported under Linux but may be supported by other systems which may comply with the FHS.

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/var/games : Variable game data (optional)

Purpose

Any variable data relating to games in /usr should be placed here. /var/games should hold the variable data previously found in /usr; static data, such as help text, level descriptions, and so on, must remain elsewhere, such as /usr/ share/games. 

   Rationale: /var/games has been given a hierarchy of its own, rather than
   leaving it merged in with the old /var/lib as in release 1.2. The
   separation allows local control of backup strategies, permissions, and disk
   usage, as well as allowing inter-host sharing and reducing clutter in /var/
   lib. Additionally, /var/games is the path traditionally used by BSD.

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/var/lib : Variable state information

Purpose

This hierarchy holds state information pertaining to an application or the system. State information is data that programs modify while they run, and that pertains to one specific host. Users must never need to modify files in /var/ lib to configure a package's operation.

State information is generally used to preserve the condition of an application (or a group of inter-related applications) between invocations and between different instances of the same application. State information should generally remain valid after a reboot, should not be logging output, and should not be spooled data.

An application (or a group of inter-related applications) must use a subdirectory of /var/lib for its data. There is one required subdirectory, /var /lib/misc, which is intended for state files that don't need a subdirectory; the other subdirectories should only be present if the application in question is included in the distribution. [38]

/var/lib/<name> is the location that must be used for all distribution packaging support. Different distributions may use different names, of course.

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Requirements

The following directories, or symbolic links to directories, are required in / var/lib:

Directory Description misc Miscellaneous state data

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Specific Options

The following directories, or symbolic links to directories, must be in /var/ lib, if the corresponding subsystem is installed:

Directory Description <editor> Editor backup files and state (optional) <pkgtool> Packaging support files (optional) <package> State data for packages and subsystems (optional) hwclock State directory for hwclock (optional) xdm X display manager variable data (optional)

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/var/lib/<editor> : Editor backup files and state (optional)

Purpose

These directories contain saved files generated by any unexpected termination of an editor (e.g., elvis, jove, nvi).

Other editors may not require a directory for crash-recovery files, but may require a well-defined place to store other information while the editor is running. This information should be stored in a subdirectory under /var/lib (for example, GNU Emacs would place lock files in /var/lib/emacs/lock).

Future editors may require additional state information beyond crash-recovery files and lock files — this information should also be placed under /var/lib/ <editor>. 

   Rationale: Previous Linux releases, as well as all commercial vendors, use
   /var/preserve for vi or its clones. However, each editor uses its own
   format for these crash-recovery files, so a separate directory is needed
   for each editor.

   Editor-specific lock files are usually quite different from the device or
   resource lock files that are stored in /var/lock and, hence, are stored
   under /var/lib.

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/var/lib/hwclock : State directory for hwclock (optional)

Purpose

This directory contains the file /var/lib/hwclock/adjtime. 

   Rationale: In FHS 2.1, this file was /etc/adjtime, but as hwclock updates
   it, that was obviously incorrect.

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/var/lib/misc : Miscellaneous variable data

Purpose

This directory contains variable data not placed in a subdirectory in /var/lib. An attempt should be made to use relatively unique names in this directory to avoid namespace conflicts. [39]

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/var/lock : Lock files

Purpose

Lock files should be stored within the /var/lock directory structure.

Lock files for devices and other resources shared by multiple applications, such as the serial device lock files that were originally found in either /usr/ spool/locks or /usr/spool/uucp, must now be stored in /var/lock. The naming convention which must be used is "LCK.." followed by the base name of the device. For example, to lock /dev/ttyS0 the file "LCK..ttyS0" would be created. [40]

The format used for the contents of such lock files must be the HDB UUCP lock file format. The HDB format is to store the process identifier (PID) as a ten byte ASCII decimal number, with a trailing newline. For example, if process 1230 holds a lock file, it would contain the eleven characters: space, space, space, space, space, space, one, two, three, zero, and newline.

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/var/log : Log files and directories

Purpose

This directory contains miscellaneous log files. Most logs must be written to this directory or an appropriate subdirectory.

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Specific Options

The following files, or symbolic links to files, must be in /var/log, if the corresponding subsystem is installed: 

 File              Description

lastlog record of last login of each user messages system messages from syslogd wtmp record of all logins and logouts

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/var/mail : User mailbox files (optional)

Purpose

The mail spool must be accessible through /var/mail and the mail spool files must take the form <username>. [41]

User mailbox files in this location must be stored in the standard UNIX mailbox format. 

   Rationale: The logical location for this directory was changed from /var/
   spool/mail in order to bring FHS in-line with nearly every UNIX
   implementation. This change is important for inter-operability since a
   single /var/mail is often shared between multiple hosts and multiple UNIX
   implementations (despite NFS locking issues).

   It is important to note that there is no requirement to physically move the
   mail spool to this location. However, programs and header files must be
   changed to use /var/mail.

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/var/opt : Variable data for /opt

Purpose

Variable data of the packages in /opt must be installed in /var/opt/<subdir>, where <subdir> is the name of the subtree in /opt where the static data from an add-on software package is stored, except where superseded by another file in / etc. No structure is imposed on the internal arrangement of /var/opt/<subdir>. 

   Rationale: Refer to the rationale for /opt.

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/var/run : Run-time variable data

Purpose

This directory contains system information data describing the system since it was booted. Files under this directory must be cleared (removed or truncated as appropriate) at the beginning of the boot process. Programs may have a subdirectory of /var/run; this is encouraged for programs that use more than one run-time file. [42] Process identifier (PID) files, which were originally placed in /etc, must be placed in /var/run. The naming convention for PID files is <program-name>.pid. For example, the crond PID file is named /var/run/ crond.pid.

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Requirements

The internal format of PID files remains unchanged. The file must consist of the process identifier in ASCII-encoded decimal, followed by a newline character. For example, if crond was process number 25, /var/run/crond.pid would contain three characters: two, five, and newline.

Programs that read PID files should be somewhat flexible in what they accept; i.e., they should ignore extra whitespace, leading zeroes, absence of the trailing newline, or additional lines in the PID file. Programs that create PID files should use the simple specification located in the above paragraph.

The utmp file, which stores information about who is currently using the system, is located in this directory.

System programs that maintain transient UNIX-domain sockets must place them in this directory.

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/var/spool : Application spool data

Purpose

/var/spool contains data which is awaiting some kind of later processing. Data in /var/spool represents work to be done in the future (by a program, user, or administrator); often data is deleted after it has been processed. [43]

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Specific Options

The following directories, or symbolic links to directories, must be in /var/ spool, if the corresponding subsystem is installed:

Directory Description lpd Printer spool directory (optional) mqueue Outgoing mail queue (optional) news News spool directory (optional) rwho Rwhod files (optional) uucp Spool directory for UUCP (optional)

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/var/spool/lpd : Line-printer daemon print queues (optional)

Purpose

The lock file for lpd, lpd.lock, must be placed in /var/spool/lpd. It is suggested that the lock file for each printer be placed in the spool directory for that specific printer and named lock.

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Specific Options

Directory Description printer Spools for a specific printer (optional)

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/var/spool/rwho : Rwhod files (optional)

Purpose

This directory holds the rwhod information for other systems on the local net. 

   Rationale: Some BSD releases use /var/rwho for this data; given its
   historical location in /var/spool on other systems and its approximate fit
   to the definition of `spooled' data, this location was deemed more
   appropriate.

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/var/tmp : Temporary files preserved between system reboots

Purpose

The /var/tmp directory is made available for programs that require temporary files or directories that are preserved between system reboots. Therefore, data stored in /var/tmp is more persistent than data in /tmp.

Files and directories located in /var/tmp must not be deleted when the system is booted. Although data stored in /var/tmp is typically deleted in a site-specific manner, it is recommended that deletions occur at a less frequent interval than /tmp.

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/var/yp : Network Information Service (NIS) database files (optional)

Purpose

Variable data for the Network Information Service (NIS), formerly known as the Sun Yellow Pages (YP), must be placed in this directory. 

   Rationale: /var/yp is the standard directory for NIS (YP) data and is
   almost exclusively used in NIS documentation and systems. [44]

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Chapter 6. Operating System Specific Annex

This section is for additional requirements and recommendations that only apply to a specific operating system. The material in this section should never conflict with the base standard.

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Linux

This is the annex for the Linux operating system.

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/ : Root directory

On Linux systems, if the kernel is located in /, we recommend using the names vmlinux or vmlinuz, which have been used in recent Linux kernel source packages.

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/bin : Essential user command binaries (for use by all users)

Linux systems which require them place these additional files into /bin: 

 • setserial

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/dev : Devices and special files

The following devices must exist under /dev.

/dev/null 

   All data written to this device is discarded. A read from this device will
   return an EOF condition.

/dev/zero 

   This device is a source of zeroed out data. All data written to this device
   is discarded. A read from this device will return as many bytes containing
   the value zero as was requested.

/dev/tty 

   This device is a synonym for the controlling terminal of a process. Once
   this device is opened, all reads and writes will behave as if the actual
   controlling terminal device had been opened.

   Rationale: Previous versions of the FHS had stricter requirements for /dev.
   Other devices may also exist in /dev. Device names may exist as symbolic
   links to other device nodes located in /dev or subdirectories of /dev.
   There is no requirement concerning major/minor number values.


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/etc : Host-specific system configuration

Linux systems which require them place these additional files into /etc. 

 • lilo.conf

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/lib64 and /lib32 : 64/32-bit libraries (architecture dependent) 

The 64-bit architectures PPC64, s390x, sparc64 and AMD64 must place 64-bit

libraries in /lib64, and 32-bit (or 31-bit on s390) libraries in /lib.

The 64-bit architecture IA64 must place 64-bit libraries in /lib. 


   Rationale: This is a refinement of the general rules for /lib<qual> and /
   usr/lib<qual>. The architectures PPC64, s390x, sparc64 and AMD64 support
   support both 32-bit (for s390 more precise 31-bit) and 64-bit programs.
   Using lib for 32-bit binaries allows existing binaries from the 32-bit
   systems to work without any changes: such binaries are expected to be
   numerous. IA-64 uses a different scheme, reflecting the deprecation of
   32-bit binaries (and hence libraries) on that architecture.

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/proc : Kernel and process information virtual filesystem

The proc filesystem is the de-facto standard Linux method for handling process and system information, rather than /dev/kmem and other similar methods. We strongly encourage this for the storage and retrieval of process information as well as other kernel and memory information.

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/sbin : Essential system binaries

Linux systems place these additional files into /sbin. 

 • Second extended filesystem commands (optional):

     □ badblocks

     □ dumpe2fs

     □ e2fsck

     □ mke2fs

     □ mklost+found

     □ tune2fs

 • Boot-loader map installer (optional):

     □ lilo

Optional files for /sbin: 

 • Static binaries:

     □ ldconfig

     □ sln

     □ ssync

   Static ln (sln) and static sync (ssync) are useful when things go wrong.
   The primary use of sln (to repair incorrect symlinks in /lib after a poorly
   orchestrated upgrade) is no longer a major concern now that the ldconfig
   program (usually located in /usr/sbin) exists and can act as a guiding hand
   in upgrading the dynamic libraries. Static sync is useful in some emergency
   situations. Note that these need not be statically linked versions of the
   standard ln and sync, but may be.

   The ldconfig binary is optional for /sbin since a site may choose to run
   ldconfig at boot time, rather than only when upgrading the shared
   libraries. (It's not clear whether or not it is advantageous to run
   ldconfig on each boot.) Even so, some people like ldconfig around for the
   following (all too common) situation:

    1. I've just removed /lib/<file>.

    2. I can't find out the name of the library because ls is dynamically
       linked, I'm using a shell that doesn't have ls built-in, and I don't
       know about using "echo *" as a replacement.

    3. I have a static sln, but I don't know what to call the link.

 • Miscellaneous:

     □ ctrlaltdel

     □ kbdrate

   So as to cope with the fact that some keyboards come up with such a high
   repeat rate as to be unusable, kbdrate may be installed in /sbin on some
   systems.

   Since the default action in the kernel for the Ctrl-Alt-Del key combination
   is an instant hard reboot, it is generally advisable to disable the
   behavior before mounting the root filesystem in read-write mode. Some init
   suites are able to disable Ctrl-Alt-Del, but others may require the
   ctrlaltdel program, which may be installed in /sbin on those systems.

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/usr/include : Header files included by C programs

These symbolic links are required if a C or C++ compiler is installed and only for systems not based on glibc. 

   /usr/include/asm -> /usr/src/linux/include/asm-<arch>
   /usr/include/linux -> /usr/src/linux/include/linux

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/usr/src : Source code

For systems based on glibc, there are no specific guidelines for this directory. For systems based on Linux libc revisions prior to glibc, the following guidelines and rationale apply:

The only source code that should be placed in a specific location is the Linux kernel source code. It is located in /usr/src/linux.

If a C or C++ compiler is installed, but the complete Linux kernel source code is not installed, then the include files from the kernel source code must be located in these directories: 

   /usr/src/linux/include/asm-<arch>
   /usr/src/linux/include/linux

<arch> is the name of the system architecture. 

   Note: /usr/src/linux may be a symbolic link to a kernel source code tree.

   Rationale: It is important that the kernel include files be located in /usr
   /src/linux and not in /usr/include so there are no problems when system
   administrators upgrade their kernel version for the first time.

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/var/spool/cron : cron and at jobs

This directory contains the variable data for the cron and at programs.

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Chapter 7. Appendix

The FHS mailing list

The FHS mailing list is located at <freestandards-fhs-discuss@lists.sourceforge.net>. You can subscribe to the mailing list at this page http://sourceforge.net/projects/freestandards/.

Thanks to Network Operations at the University of California at San Diego who allowed us to use their excellent mailing list server.

As noted in the introduction, please do not send mail to the mailing list without first contacting the FHS editor or a listed contributor.

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Background of the FHS

The process of developing a standard filesystem hierarchy began in August 1993 with an effort to restructure the file and directory structure of Linux. The FSSTND, a filesystem hierarchy standard specific to the Linux operating system, was released on February 14, 1994. Subsequent revisions were released on October 9, 1994 and March 28, 1995.

In early 1995, the goal of developing a more comprehensive version of FSSTND to address not only Linux, but other UNIX-like systems was adopted with the help of members of the BSD development community. As a result, a concerted effort was made to focus on issues that were general to UNIX-like systems. In recognition of this widening of scope, the name of the standard was changed to Filesystem Hierarchy Standard or FHS for short.

Volunteers who have contributed extensively to this standard are listed at the end of this document. This standard represents a consensus view of those and other contributors.

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General Guidelines

Here are some of the guidelines that have been used in the development of this standard: 

 • Solve technical problems while limiting transitional difficulties.

 • Make the specification reasonably stable.

 • Gain the approval of distributors, developers, and other decision-makers in
   relevant development groups and encourage their participation.

 • Provide a standard that is attractive to the implementors of different
   UNIX-like systems.

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Scope

This document specifies a standard filesystem hierarchy for FHS filesystems by specifying the location of files and directories, and the contents of some system files.

This standard has been designed to be used by system integrators, package developers, and system administrators in the construction and maintenance of FHS compliant filesystems. It is primarily intended to be a reference and is not a tutorial on how to manage a conforming filesystem hierarchy.

The FHS grew out of earlier work on FSSTND, a filesystem organization standard for the Linux operating system. It builds on FSSTND to address interoperability issues not just in the Linux community but in a wider arena including 4.4BSD-based operating systems. It incorporates lessons learned in the BSD world and elsewhere about multi-architecture support and the demands of heterogeneous networking.

Although this standard is more comprehensive than previous attempts at filesystem hierarchy standardization, periodic updates may become necessary as requirements change in relation to emerging technology. It is also possible that better solutions to the problems addressed here will be discovered so that our solutions will no longer be the best possible solutions. Supplementary drafts may be released in addition to periodic updates to this document. However, a specific goal is backwards compatibility from one release of this document to the next.

Comments related to this standard are welcome. Any comments or suggestions for changes may be directed to the FHS editor (Daniel Quinlan <quinlan@pathname.com>) or the FHS mailing list. Typographical or grammatical comments should be directed to the FHS editor.

Before sending mail to the mailing list it is requested that you first contact the FHS editor in order to avoid excessive re-discussion of old topics.

Questions about how to interpret items in this document may occasionally arise. If you have need for a clarification, please contact the FHS editor. Since this standard represents a consensus of many participants, it is important to make certain that any interpretation also represents their collective opinion. For this reason it may not be possible to provide an immediate response unless the inquiry has been the subject of previous discussion.

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Acknowledgments

The developers of the FHS wish to thank the developers, system administrators, and users whose input was essential to this standard. We wish to thank each of the contributors who helped to write, compile, and compose this standard.

The FHS Group also wishes to thank those Linux developers who supported the FSSTND, the predecessor to this standard. If they hadn't demonstrated that the FSSTND was beneficial, the FHS could never have evolved.

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Contributors

Brandon S. Allbery <bsa@kf8nh.wariat.org> Keith Bostic <bostic@cs.berkeley.edu> Drew Eckhardt <drew@colorado.edu> Rik Faith <faith@cs.unc.edu> Stephen Harris <sweh@spuddy.mew.co.uk> Ian Jackson <ijackson@cus.cam.ac.uk> Andreas Jaeger <aj@suse.de> John A. Martin <jmartin@acm.org> Ian McCloghrie <ian@ucsd.edu> Chris Metcalf <metcalf@lcs.mit.edu> Ian Murdock <imurdock@debian.org> David C. Niemi <niemidc@clark.net> Daniel Quinlan <quinlan@pathname.com> Eric S. Raymond <esr@thyrsus.com> Rusty Russell <rusty@rustcorp.com.au> Mike Sangrey <mike@sojurn.lns.pa.us> David H. Silber <dhs@glowworm.firefly.com> Thomas Sippel-Dau <t.sippel-dau@ic.ac.uk> Theodore Ts'o <tytso@athena.mit.edu> Stephen Tweedie <sct@dcs.ed.ac.uk> Fred N. van Kempen <waltje@infomagic.com> Bernd Warken <bwarken@mayn.de> Christopher Yeoh <cyeoh@samba.org>

Notes

[1] Command binaries that are not essential enough to place into /bin must be 

    placed in /usr/bin, instead. Items that are required only by non-root
    users (the X Window System, chsh, etc.) are generally not essential enough
    to be placed into the root partition.

[2] Programs necessary to arrange for the boot loader to be able to boot a 

    file must be placed in /sbin. Configuration files for boot loaders must be
    placed in /etc.

    The GRUB bootloader reads its configurations file before booting, so that
    must be placed in /boot. However, it is a configuration file, so should be
    in /etc. The answer here is a symbolic link such as /etc/grub/menu.lst ->
    /boot/menu.lst.

[3] On some i386 machines, it may be necessary for /boot to be located on a 

    separate partition located completely below cylinder 1024 of the boot
    device due to hardware constraints.

    Certain MIPS systems require a /boot partition that is a mounted MS-DOS
    filesystem or whatever other filesystem type is accessible for the
    firmware. This may result in restrictions with respect to usable filenames
    within /boot (only for affected systems).

[4] The setup of command scripts invoked at boot time may resemble System V, 

    BSD or other models. Further specification in this area may be added to a
    future version of this standard.

[5] It is recommended that files be stored in subdirectories of /etc rather 

    than directly in /etc.

[6] Systems that use the shadow password suite will have additional 

    configuration files in /etc (/etc/shadow and others) and programs in /usr/
    sbin (useradd, usermod, and others).

[7] On some Linux systems, this may be a symbolic link to /proc/mounts, in 

    which case this exception is not required.

[8] /etc/X11/xdm holds the configuration files for xdm. These are most of the 

    files previously found in /usr/lib/X11/xdm. Some local variable data for
    xdm is stored in /var/lib/xdm.

[9] Different people prefer to place user accounts in a variety of places. 

    This section describes only a suggested placement for user home
    directories; nevertheless we recommend that all FHS-compliant
    distributions use this as the default location for home directories.

    On small systems, each user's directory is typically one of the many
    subdirectories of /home such as /home/smith, /home/torvalds, /home/
    operator, etc. On large systems (especially when the /home directories are
    shared amongst many hosts using NFS) it is useful to subdivide user home
    directories. Subdivision may be accomplished by using subdirectories such
    as /home/staff, /home/guests, /home/students, etc.

[10] If you want to find out a user's home directory, you should use the 

    getpwent(3) library function rather than relying on /etc/passwd because
    user information may be stored remotely using systems such as NIS.

[11] It is recommended that apart from autosave and lock files programs should 

    refrain from creating non dot files or directories in a home directory
    without user intervention.

[12] Shared libraries that are only necessary for binaries in /usr (such as any 

    X Window binaries) must not be in /lib. Only the shared libraries required
    to run binaries in /bin and /sbin may be here. In particular, the library
    libm.so.* may also be placed in /usr/lib if it is not required by anything
    in /bin or /sbin.

[13] The usual placement of this binary is /usr/bin/cpp.

[14] This is commonly used for 64-bit or 32-bit support on systems which 

    support multiple binary formats, but require libraries of the same name.
    In this case, /lib32 and /lib64 might be the library directories, and /lib
    a symlink to one of them.

[15] /lib<qual>/cpp is still permitted: this allows the case where /lib and / 

    lib<qual> are the same (one is a symbolic link to the other).

[16] A compliant implementation with two CDROM drives might have /media/cdrom0 

    and /media/cdrom1 with /media/cdrom a symlink to either of these.

[17] If the home directory of the root account is not stored on the root 

    partition it will be necessary to make certain it will default to / if it
    can not be located.

    We recommend against using the root account for tasks that can be
    performed as an unprivileged user, and that it be used solely for system
    administration. For this reason, we recommend that subdirectories for mail
    and other applications not appear in the root account's home directory,
    and that mail for administration roles such as root, postmaster, and
    webmaster be forwarded to an appropriate user.

[18] Originally, /sbin binaries were kept in /etc.

[19] Deciding what things go into "sbin" directories is simple: if a normal 

    (not a system administrator) user will ever run it directly, then it must
    be placed in one of the "bin" directories. Ordinary users should not have
    to place any of the sbin directories in their path.

    For example, files such as chfn which users only occasionally use must
    still be placed in /usr/bin. ping, although it is absolutely necessary for
    root (network recovery and diagnosis) is often used by users and must live
    in /bin for that reason.

    We recommend that users have read and execute permission for everything in
    /sbin except, perhaps, certain setuid and setgid programs. The division
    between /bin and /sbin was not created for security reasons or to prevent
    users from seeing the operating system, but to provide a good partition
    between binaries that everyone uses and ones that are primarily used for
    administration tasks. There is no inherent security advantage in making /
    sbin off-limits for users.

[20] This is particularly important as these areas will often contain both 

    files initially installed by the distributor, and those added by the
    administrator.

[21] Examples of such configuration files include Xconfig, XF86Config, or 

    system.twmrc)

[22] Miscellaneous architecture-independent application-specific static files 

    and subdirectories must be placed in /usr/share.

[23] For example, the perl5 subdirectory for Perl 5 modules and libraries.

[24] Some executable commands such as makewhatis and sendmail have also been 

    traditionally placed in /usr/lib. makewhatis is an internal binary and
    must be placed in a binary directory; users access only catman. Newer
    sendmail binaries are now placed by default in /usr/sbin. Additionally,
    systems using a sendmail-compatible mail transfer agent must provide /usr/
    sbin/sendmail as a symbolic link to the appropriate executable.

[25] Host-specific data for the X Window System must not be stored in /usr/lib/ 

    X11. Host-specific configuration files such as Xconfig or XF86Config must
    be stored in /etc/X11. This includes configuration data such as
    system.twmrc even if it is only made a symbolic link to a more global
    configuration file (probably in /usr/X11R6/lib/X11).

[26] The case where /usr/lib and /usr/lib<qual> are the same (one is a symbolic 

    link to the other) these files and the per-application subdirectories will
    exist.

[27] Software placed in / or /usr may be overwritten by system upgrades (though 

    we recommend that distributions do not overwrite data in /etc under these
    circumstances). For this reason, local software must not be placed outside
    of /usr/local without good reason.

[28] /usr/local/man may be deprecated in future FHS releases, so if all else is 

    equal, making that one a symlink seems sensible.

[29] Locally installed system administration programs should be placed in /usr/ 

    local/sbin.

[30] Much of this data originally lived in /usr (man, doc) or /usr/lib (dict, 

    terminfo, zoneinfo).

[31] Obviously, there are no manual pages in / because they are not required at 

    boot time nor are they required in emergencies. Really.

[32] For example, if /usr/local/man has no manual pages in section 4 (Devices), 

    then /usr/local/man/man4 may be omitted.

[33] A major exception to this rule is the United Kingdom, which is `GB' in the 

    ISO 3166, but `UK' for most email addresses.

[34] Some such files include: airport, birthtoken, eqnchar, getopt, 

    gprof.callg, gprof.flat, inter.phone, ipfw.samp.filters,
    ipfw.samp.scripts, keycap.pcvt, mail.help, mail.tildehelp, man.template,
    map3270, mdoc.template, more.help, na.phone, nslookup.help, operator,
    scsi_modes, sendmail.hf, style, units.lib, vgrindefs, vgrindefs.db,
    zipcodes

[35] Generally, source should not be built within this hierarchy.

[36] This standard does not currently incorporate the TeX Directory Structure 

    (a document that describes the layout TeX files and directories), but it
    may be useful reading. It is located at ftp://ctan.tug.org/tex/

[37] For example, /usr/share/man/man1/ls.1 is formatted into /var/cache/man/ 

    cat1/ls.1, and /usr/X11R6/man/<locale>/man3/XtClass.3x into /var/cache/man
    /X11R6/<locale>/cat3/XtClass.3x.

[38] An important difference between this version of this standard and previous 

    ones is that applications are now required to use a subdirectory of /var/
    lib.

[39] This hierarchy should contain files stored in /var/db in current BSD 

    releases. These include locate.database and mountdtab, and the kernel
    symbol database(s).

[40] Then, anything wishing to use /dev/ttyS0 can read the lock file and act 

    accordingly (all locks in /var/lock should be world-readable).

[41] Note that /var/mail may be a symbolic link to another directory.

[42] /var/run should be unwritable for unprivileged users (root or users 

    running daemons); it is a major security problem if any user can write in
    this directory.

[43] UUCP lock files must be placed in /var/lock. See the above section on /var 

    /lock.

[44] NIS should not be confused with Sun NIS+, which uses a different 

    directory, /var/nis.
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