.\" (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
.\" This file can be distributed under the terms of the GNU General Public
.\" License.
.\" Modified Sun Jul 25 11:05:58 1993 by Rik Faith (faith@cs.unc.edu)
.TH HIER 7  "April 24, 1993" "Linux" "Linux Programmer's Manual"
.SH NAME
hier \- Description of the file system 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 executed often,
are needed to bring the system up or repair it.
.TP
.I /dev
Special or device files, which refer to physical devices.  See
mknod(1).
.TP
.I /dos
If both MS\-DOS and Linux are run on one computer, this is a typical
place to mount a DOS file system.
.TP
.I /etc
contains programs and other files necessary to system administration;
normal users don't need any of this.  Usually, this directory is not
in their
.BR $PATH .
.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/lilo
The Linux Loader for booting the system goes here.
.TP
.I /install
This is used by some installations scripts to keep track of which
packages have been installed.
.TP
.I /lib
Frequently\-used object code libaries, including dynamic libraries,
which are linked at the time an executable starts up, plus some
executables which usually are not called directly.
.TP
.I /proc
This is the directory where information about running processes can be
obtained.
.TP
.I /proc/[0-9]+
This directory contains information about the process associated with
its number; it has such files as the command line, the environment,
the memory contents, or statistics about the process.
.TP
.I /proc/[0-9]+/fd
A directory containing the file descriptors associated with the
process.
.TP
.I /proc/[0-9]+/lib
A directory containing the dynamic libraries associated with a process.
.TP
.I /proc/self
This is a link to the directory associated with the calling process.
.TP
.I /tmp
This directory contains temporary files which may be deleted with no
notice, such as by a regular job or at system bootup.
.TP
.I /user
This often is an empty directory, which can be used as a mount point
for floppy disks.
.TP
.I /usr
Less\-frequently used commands and other things; this is often a mount
point for a separate partition or volume.
.TP
.I /usr/TeX
The TeX typesetting system.
.TP
.I /usr/TeX/bin
Binary commands for the TeX system.
.I /usr/TeX/lib
This contains data files connected with TeX, and may contain further
subdirectories.
.TP
.I /usr/TeX/man
Manual pages with the TeX system.
.TP
.I /usr/TeX/src
Sources associates with TeX.
.TP
.I /usr/X386
The X-\Windows system.
.TP
.I /usr/X386/bin
Binaries which belong to the X\-Windows system; often, there is a
symbolic link from the more traditional
.I /usr/bin/X11
to here.
.TP
.I /usr/X386/lib
Data files associated with the X\-Windows system.
.TP
.I /usr/X386/lib/X11
These contain miscellaneous files needed to run X; among them
configuration files.  Often, there is a symbolic link from
.I /usr/lib/X11
to this directory.
.TP
.I /usr/adm
This often contains various logfiles.
.TP
.I /usr/bin
This contains binaries which are not needed so often, or are not
needed for bringing the system up or repairing it.  The descision
wether to put something in
.I /bin
or
.I /usr/bin
shoud be guided by the simple consideration:  "If I put it in
.I /usr/bin
and
.I /usr
is not available on boot, do I still get the system up?"
.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/X386/bin .
.TP
.I /usr/g++-include
Include files to use with the GNU C++ compiler.
.TP
.I /usr/homes
This contains the home directories for normal users.
.TP
.I /usr/include
Include files for the C compiler.
.TP
.I /usr/include/X11
Incude files for the C compiler and the X\-Windows system.
.TP
.I /usr/include/asm
Include files which declare some assembler functions.  This should 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 should be a symbolic link to
.I /usr/src/linux/include/linux
to get at operating system specific information.
.TP
.I /usr/lib
Less -\ frequently used 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/X386/lib/X11 .
.TP
.I /usr/lib/X11/app-defaults
X applications store their default resource (in other words,
application defaults) here.  If you want to change the way a certain
program looks, this is the place to look.
.TP
.I /usr/lib/X11/config
This directory is used for the
.BR imake (1)
utility which incorporates information about the system into
Makefiles.
.TP
.I /usr/lib/X11/twm
Files for the
.BR twm (1)
window manager.
.TP
.I /usr/lib/X11/xinit
Files for starting up the X Windows system.
.TP
.I /usr/lib/gcc-lib
contains configuration files for the system's C compiler,
.BR gcc (1).
.TP
.I /usr/lib/groff
Files for the groff document formatting system.
.TP
.I /usr/lib/uucp
Files for 
.BR uucp (1).
.TP
.I /usr/lib/zoneinfo
Files for timezone information.
.TP
.I /usr/local
This is where programs which are local to the site typically go in.
Some program packages, such as EMACS, may have their own
subdirectories there.
.TP
.I /usr/local/bin
Binaries for programs local to the site go there.
.TP
.I /usr/local/lib
Files associated with locally installed programs go there.
.TP
.I /usr/local/man
Manpages associated with locally installed programs go there.
.TP
.I /usr/man
Manpages go in there, into their subdirectories.
.TP
.I /usr/man/cat[1-9]
These directories contain preformatted manual pages according to their
manpage section.
.TP
.I /usr/man/man[1-9]
These directories contain manual pagaes which are in source code form.
.TP
.I /usr/openwin
Files associated with the Open Windows Window manager for X go there.
.TP
.I /usr/preserve
This is where
.BR vi (1)
saves edit sessions so they can be restored later.
.TP
.I /usr/spool
Spooled (or queued) files for various programs.
.TP
.I /usr/spool/atjobs
Spooled jobs for
.BR at (1).
.TP
.I /usr/spool/cron
Spooled jobs for
.BR cron (1).
.TP
.I /usr/spool/lp1
Spooled files for a printer.
.TP
.I /usr/spool/mail
User's mailboxes.
.TP
.I /usr/spool/smail
Spooled files for the
.BR smail (1)
mail delivery program.
.TP
.I /usr/spool/uucp
Spooled files for
.BR uucp (1).
.TP
.I /usr/src
Source files for different parts of the system.
.TP
.I /usr/src/libc-linux
Sources for the C library.
.TP
.I /usr/src/linux
This contains the sources for the operating system itself.
.TP
.I /usr/tmp
An alternative place to store temporary files; often used if the files
will be huge.
.TP
.I /var
On soqme systems with more of a BSD flavour to them, this directory
contains all the files which may change in size, such as spool and log
files, and
.I /usr
only contains static files.  Often,
.I /var
is just a symbolic link to
.IR /usr .
.SH "CONFORMS TO"
The layout of this file system generally follows System V
conventions.
.SH BUGS
This list is not exhaustive; different systems may be configured
differently.
.SH SEE ALSO
.BR find "(1), " ln "(1), " mount (1)