clone.2, getpid.2, credentials.7: Replace reference to namespaces(7) with pid_namespa...

[man-pages.git] / man7 / hier.7

.\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
.\"
.\" %%%LICENSE_START(VERBATIM)
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Permission is granted to copy and distribute modified versions of this
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one.
.\"
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date.  The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein.  The author(s) may not
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.\" %%%LICENSE_END
.\"
.\" Modified Sun Jul 25 11:05:58 1993 by Rik Faith (faith@cs.unc.edu)
.\" Modified Sat Feb 10 16:18:03 1996 by Urs Thuermann (urs@isnogud.escape.de)
.\" Modified Mon Jun 16 20:02:00 1997 by Nicolás Lichtmaier <nick@debian.org>
.\" Modified Mon Feb  6 16:41:00 1999 by Nicolás Lichtmaier <nick@debian.org>
.\" Modified Tue Feb  8 16:46:45 2000 by Chris Pepper <pepper@tgg.com>
.\" Modified Fri Sep  7 20:32:45 2001 by Tammy Fox <tfox@redhat.com>
.TH HIER 7 2012-08-05 "Linux" "Linux Programmer's Manual"
.SH NAME
hier \- description of the filesystem hierarchy
.SH DESCRIPTION
A typical Linux system has, among others, the following directories:
.TP
.I /
This is the root directory.
This is where the whole tree starts.
.TP
.I /bin
This directory contains executable programs which are needed in
single user mode and to bring the system up or repair it.
.TP
.I /boot
Contains static files for the boot loader.
This directory holds only
the files which are needed during the boot process.
The map installer
and configuration files should go to
.I /sbin
and
.IR /etc .
.TP
.I /dev
Special or device files, which refer to physical devices.
See
.BR mknod (1).
.TP
.I /etc
Contains configuration files which are local to the machine.
Some
larger software packages, like X11, can have their own subdirectories
below
.IR /etc .
Site-wide configuration files may be placed here or in
.IR /usr/etc .
Nevertheless, programs should always look for these files in
.I /etc
and you may have links for these files to
.IR /usr/etc .
.TP
.I /etc/opt
Host-specific configuration files for add-on applications installed
in
.IR /opt .
.TP
.I /etc/sgml
This directory contains the configuration files for SGML and XML (optional).
.TP
.I /etc/skel
When a new user account is created, files from this directory are
usually copied into the user's home directory.
.TP
.I /etc/X11
Configuration files for the X11 window system (optional).
.TP
.I /home
On machines with home directories for users, these are usually beneath
this directory, directly or not.
The structure of this directory
depends on local administration decisions.
.TP
.I /lib
This directory should hold those shared libraries that are necessary
to boot the system and to run the commands in the root filesystem.
.TP
.I /media
This directory contains mount points for removable media such as CD
and DVD disks or USB sticks.
.TP
.I /mnt
This directory is a mount point for a temporarily mounted filesystem.
In some distributions,
.I /mnt
contains subdirectories intended to be used as mount points for several
temporary filesystems.
.TP
.I /opt
This directory should contain add-on packages that contain static files.
.TP
.I /proc
This is a mount point for the
.I proc
filesystem, which provides information about running processes and
the kernel.
This pseudo-filesystem is described in more detail in
.BR proc (5).
.TP
.I /root
This directory is usually the home directory for the root user (optional).
.TP
.I /sbin
Like
.IR /bin ,
this directory holds commands needed to boot the system, but which are
usually not executed by normal users.
.TP
.I /srv
This directory contains site-specific data that is served by this system.
.TP
.I /tmp
This directory contains temporary files which may be deleted with no
notice, such as by a regular job or at system boot up.
.TP
.I /usr
This directory is usually mounted from a separate partition.
It should hold only sharable, read-only data, so that it can be mounted
by various machines running Linux.
.TP
.I /usr/X11R6
The X\-Window system, version 11 release 6 (optional).
.TP
.I /usr/X11R6/bin
Binaries which belong to the X\-Window system; often, there is a
symbolic link from the more traditional
.I /usr/bin/X11
to here.
.TP
.I /usr/X11R6/lib
Data files associated with the X\-Window system.
.TP
.I /usr/X11R6/lib/X11
These contain miscellaneous files needed to run X;  Often, there is a
symbolic link from
.I /usr/lib/X11
to this directory.
.TP
.I /usr/X11R6/include/X11
Contains include files needed for compiling programs using the X11
window system.
Often, there is a symbolic link from
.I /usr/include/X11
to this directory.
.TP
.I /usr/bin
This is the primary directory for executable programs.
Most programs
executed by normal users which are not needed for booting or for
repairing the system and which are not installed locally should be
placed in this directory.
.TP
.I /usr/bin/X11
is the traditional place to look for X11 executables; on Linux, it
usually is a symbolic link to
.IR /usr/X11R6/bin .
.TP
.I /usr/dict
Replaced by
.IR /usr/share/dict .
.TP
.I /usr/doc
Replaced by
.IR /usr/share/doc .
.TP
.I /usr/etc
Site-wide configuration files to be shared between several machines
may be stored in this directory.
However, commands should always
reference those files using the
.I /etc
directory.
Links from files in
.I /etc
should point to the appropriate files in
.IR /usr/etc .
.TP
.I /usr/games
Binaries for games and educational programs (optional).
.TP
.I /usr/include
Include files for the C compiler.
.TP
.I /usr/include/X11
Include files for the C compiler and the X\-Window system.
This is
usually a symbolic link to
.IR /usr/X11R6/include/X11 .
.TP
.I /usr/include/asm
Include files which declare some assembler functions.
This used to be a
symbolic link to
.IR /usr/src/linux/include/asm .
.TP
.I /usr/include/linux
This contains information which may change from system release to
system release and used to be a symbolic link to
.I /usr/src/linux/include/linux
to get at operating-system-specific information.

(Note that one should have include files there that work correctly with
the current libc and in user space.
However, Linux kernel source is not
designed to be used with user programs and does not know anything
about the libc you are using.
It is very likely that things will break
if you let
.I /usr/include/asm
and
.I /usr/include/linux
point at a random kernel tree.
Debian systems don't do this
and use headers from a known good kernel
version, provided in the libc*-dev package.)
.TP
.I /usr/include/g++
Include files to use with the GNU C++ compiler.
.TP
.I /usr/lib
Object libraries, including dynamic libraries, plus some executables
which usually are not invoked directly.
More complicated programs may
have whole subdirectories there.
.TP
.I /usr/lib/X11
The usual place for data files associated with X programs, and
configuration files for the X system itself.
On Linux, it usually is
a symbolic link to
.IR /usr/X11R6/lib/X11 .
.TP
.I /usr/lib/gcc-lib
contains executables and include files for the GNU C compiler,
.BR gcc (1).
.TP
.I /usr/lib/groff
Files for the GNU groff document formatting system.
.TP
.I /usr/lib/uucp
Files for
.BR uucp (1).
.TP
.I /usr/local
This is where programs which are local to the site typically go.
.TP
.I /usr/local/bin
Binaries for programs local to the site.
.TP
.I /usr/local/doc
Local documentation.
.TP
.I /usr/local/etc
Configuration files associated with locally installed programs.
.TP
.I /usr/local/games
Binaries for locally installed games.
.TP
.I /usr/local/lib
Files associated with locally installed programs.
.TP
.I /usr/local/include
Header files for the local C compiler.
.TP
.I /usr/local/info
Info pages associated with locally installed programs.
.TP
.I /usr/local/man
Man pages associated with locally installed programs.
.TP
.I /usr/local/sbin
Locally installed programs for system administration.
.TP
.I /usr/local/share
Local application data that can be shared among different architectures
of the same OS.
.TP
.I /usr/local/src
Source code for locally installed software.
.TP
.I /usr/man
Replaced by
.IR /usr/share/man .
.TP
.I /usr/sbin
This directory contains program binaries for system administration
which are not essential for the boot process, for mounting
.IR /usr ,
or for system repair.
.TP
.I /usr/share
This directory contains subdirectories with specific application data, that
can be shared among different architectures of the same OS.
Often one finds stuff here that used to live in
.I /usr/doc
or
.I /usr/lib
or
.IR /usr/man .
.TP
.I /usr/share/dict
Contains the word lists used by spell checkers.
.TP
.I /usr/share/doc
Documentation about installed programs.
.TP
.I /usr/share/games
Static data files for games in
.IR /usr/games .
.TP
.I /usr/share/info
Info pages go here.
.TP
.I /usr/share/locale
Locale information goes here.
.TP
.I /usr/share/man
Manual pages go here in subdirectories according to the man page sections.
.TP
.I /usr/share/man/<locale>/man[1\-9]
These directories contain manual pages for the
specific locale in source code form.
Systems which use a unique language and code set for all manual pages
may omit the <locale> substring.
.TP
.I /usr/share/misc
Miscellaneous data that can be shared among different architectures of the
same OS.
.TP
.I /usr/share/nls
The message catalogs for native language support go here.
.TP
.I /usr/share/sgml
Files for SGML and XML.
.TP
.I /usr/share/terminfo
The database for terminfo.
.TP
.I /usr/share/tmac
Troff macros that are not distributed with groff.
.TP
.I /usr/share/zoneinfo
Files for timezone information.
.TP
.I /usr/src
Source files for different parts of the system, included with some packages
for reference purposes.
Don't work here with your own projects, as files
below /usr should be read-only except when installing software.
.TP
.I /usr/src/linux
This was the traditional place for the kernel source.
Some distributions put here the source for the default kernel they ship.
You should probably use another directory when building your own kernel.
.TP
.I /usr/tmp
Obsolete.
This should be a link
to
.IR /var/tmp .
This link is present only for compatibility reasons and shouldn't be used.
.TP
.I /var
This directory contains files which may change in size, such as spool
and log files.
.TP
.I /var/adm
This directory is superseded by
.I /var/log
and should be a symbolic link to
.IR /var/log .
.TP
.I /var/backups
Reserved for historical reasons.
.TP
.I /var/cache
Data cached for programs.
.TP
.IR /var/catman/cat[1\-9] " or " /var/cache/man/cat[1\-9]
These directories contain preformatted manual pages according to their
man page section.
(The use of preformatted manual pages is deprecated.)
.TP
.I /var/cron
Reserved for historical reasons.
.TP
.I /var/lib
Variable state information for programs.
.TP
.I /var/local
Variable data for
.IR /usr/local .
.TP
.I /var/lock
Lock files are placed in this directory.
The naming convention for
device lock files is
.I LCK..<device>
where
.I <device>
is the device's name in the filesystem.
The format used is that of HDU UUCP lock files, that is, lock files
contain a PID as a 10-byte ASCII decimal number, followed by a newline
character.
.TP
.I /var/log
Miscellaneous log files.
.TP
.I /var/opt
Variable data for
.IR /opt .
.TP
.I /var/mail
Users' mailboxes.
Replaces
.IR /var/spool/mail .
.TP
.I /var/msgs
Reserved for historical reasons.
.TP
.I /var/preserve
Reserved for historical reasons.
.TP
.I /var/run
Run-time variable files, like files holding process identifiers (PIDs)
and logged user information
.IR (utmp) .
Files in this directory are usually cleared when the system boots.
.TP
.I /var/spool
Spooled (or queued) files for various programs.
.TP
.I /var/spool/at
Spooled jobs for
.BR at (1).
.TP
.I /var/spool/cron
Spooled jobs for
.BR cron (8).
.TP
.I /var/spool/lpd
Spooled files for printing.
.TP
.I /var/spool/mail
Replaced by
.IR /var/mail .
.TP
.I /var/spool/mqueue
Queued outgoing mail.
.TP
.I /var/spool/news
Spool directory for news.
.TP
.I /var/spool/rwho
Spooled files for
.BR rwhod (8).
.TP
.I /var/spool/smail
Spooled files for the
.BR smail (1)
mail delivery program.
.TP
.I /var/spool/uucp
Spooled files for
.BR uucp (1).
.TP
.I /var/tmp
Like
.IR /tmp ,
this directory holds temporary files stored for an unspecified duration.
.TP
.I /var/yp
Database files for NIS.
.SH CONFORMING TO
The Filesystem Hierarchy Standard, Version 2.2
.UR http://www.pathname.com\:/fhs/
.UE .
.SH BUGS
This list is not exhaustive; different systems may be configured
differently.
.SH SEE ALSO
.BR find (1),
.BR ln (1),
.BR proc (5),
.BR mount (8)

The Filesystem Hierarchy Standard