Editing Filesystem Hierarchy Standard

{{Short description|Linux standard for directory structure}}
{{Use dmy dates|date=November 2021}}
{{Infobox technology standard
| title             = Filesystem Hierarchy Standard
| status            = Published
| year_started      = {{Start date and age|1994|02|14|df=yes}}
| version           = 3.0
| version_date      = {{Start date and age|2015|06|03|df=yes}}
| organization      = [[Linux Foundation]]
| related_standards = 
| abbreviation      = FHS
| domain            = [[Directory structure]]
| website           = {{Official website|https://refspecs.linuxfoundation.org/fhs.shtml}}<br>{{Official website|http://www.pathname.com/fhs/|Official website (Historical)}}
}}

The '''Filesystem Hierarchy Standard''' ('''FHS''') is a reference describing the conventions used for the layout of [[Unix-like]] systems. It has been made popular by its use in [[Linux distribution]]s, but it is used by other Unix-like systems as well.<ref>{{Cite web|url=https://wiki.linuxfoundation.org/lsb/fhs|title=FHS|website=The Linux Foundation Wiki|access-date=2022-01-04}}</ref> It is maintained by the [[Linux Foundation]]. The latest version is 3.0, released on 3 June 2015.<ref>{{Cite web |title=lsb:fhs-30 [Wiki] |url=https://wiki.linuxfoundation.org/lsb/fhs-30 |access-date=2023-02-22 |website=wiki.linuxfoundation.org}}</ref>

==Directory structure==
[[File:Root directory hierarchy on Linux screenshot.webp|300px|thumb|Filesystem hierarchy in [[openSUSE]]]]
In the FHS, all files and [[directory (file systems)|directories]] appear under the [[root directory]] <code>/</code>, even if they are stored on different physical or virtual devices. Some of these directories only exist in a particular system if certain subsystems, such as the [[X Window System]], are installed.

Most of these directories exist in all [[Unix-like]] operating systems and are generally used in much the same way; however, the descriptions here are those used specifically for the FHS and are not considered authoritative for platforms other than Linux.

{| class="wikitable" summary="A description of the hierarchy specified in the FHS."
|-
!Directory
!Description
|-
|<code>/</code>
|''Primary hierarchy'' root and [[root directory]] of the entire file system hierarchy.
|-
|<code>/bin</code>
|Essential command [[executable|binaries]] that need to be available in [[single-user mode]], including to bring up the system or repair it,<ref>{{Cite web|title=hier(7) - Linux manual page|url=https://man7.org/linux/man-pages/man7/hier.7.html|access-date=2021-01-06|website=man7.org}}</ref> for all users (e.g., [[cat (Unix)|cat]], [[ls]], [[cp (Unix)|cp]]).
|-
|<code>[[Boot folder|/boot]]</code>
|[[Boot loader]] files (e.g., [[Kernel (operating system)|kernel]]s, [[initrd]]).
|-
|<code>[[/dev]]</code>
|[[Device file]]s (e.g., <code>[[Null device|/dev/null]]</code>, <code>/dev/disk0</code>,  <code>/dev/sda1</code>, <code>/dev/tty</code>, <code>[[%2Fdev%2Frandom]]</code>).
|-
|<code>/etc</code>
<!-- Please see the talk page before changing this -->
|Host-specific system-wide [[configuration file]]s.<br />
There has been controversy over the meaning of the name itself. In early versions of the UNIX Implementation Document from Bell Labs, <code>/etc</code> is referred to as the ''[[et cetera|etcetera]] directory'',<ref>{{cite book |author=J. DeFelicc |title=Preliminary Release of UNIX Implementation Document |date=1972-03-17 |id=IMO.1-1 |section=E.0 |page=8 |issue=D |url=http://www.bitsavers.org/pdf/att/unix/Early_UNIX/PreliminaryUnixImplementationDocument_Jun72.pdf |access-date=6 June 2024}}</ref> as this directory historically held everything that did not belong elsewhere (however, the FHS restricts <code>/etc</code> to static configuration files and may not contain binaries).<ref name="/etc">{{cite web |url= http://www.pathname.com/fhs/pub/fhs-2.3.html#ETCHOSTSPECIFICSYSTEMCONFIGURATION |title=/etc : Host-specific system configuration |work=Filesystem Hierarchy Standard 2.3|access-date=18 February 2016}}</ref> Since the publication of early documentation, the directory name has been re-explained in various ways. Recent interpretations include [[backronym]]s such as "Editable Text Configuration" or "Extended Tool Chest".<ref>[http://ask.slashdot.org/article.pl?sid=07/03/03/028258 Define - /etc?], Posted by Cliff, 3 March 2007 - Slashdot.</ref>
|-
|<code>/etc/opt</code>
|Configuration files for add-on packages stored in <code>/opt</code>.
|-
|<code>/etc/sgml</code>
|Configuration files, such as catalogs, for software that processes [[SGML]].
|-
|<code>/etc/X11</code>
|Configuration files for the [[X Window System]], version 11.
|-
|<code>/etc/xml</code>
|Configuration files, such as catalogs, for software that processes [[XML]].
|-
|<code>/home</code>
|Users' [[home directory|home directories]], containing saved files, personal settings, etc.
|-
|<code>/lib</code>
|[[Library (computer science)|Libraries]] essential for the [[binaries]] in <code>/bin</code> and <code>/sbin</code>.
|-
|<code>/lib&lt;qual&gt;</code>
|Alternate format essential libraries. These are typically used on systems that support more than one executable code format, such as systems supporting [[32-bit]] and [[64-bit]] versions of an [[instruction set]].  Such directories are optional, but if they exist, they have some requirements.
|-
|<code>/media</code>
|Mount points for [[removable media]] such as [[CD-ROM]]s (appeared in FHS-2.3 in 2004).
|-
|<code>/mnt</code>
|Temporarily [[mount (computing)|mounted]] filesystems.
|-
|<code>/opt</code>
|Add-on [[application software]] [[Software package (installation)|packages]].<ref name="/opt">{{cite web |url=http://www.pathname.com/fhs/pub/fhs-2.3.html#OPTADDONAPPLICATIONSOFTWAREPACKAGES |title=/opt : Add-on application software packages |work=Filesystem Hierarchy Standard 2.3 |access-date=18 February 2016}}</ref>
|-
|<code>[[/proc]]</code>
|Virtual [[File system|filesystem]] providing [[process (computing)|process]] and [[kernel (operating system)|kernel]] information as files. In Linux, corresponds to a [[procfs]] mount. Generally, automatically generated and populated by the system, on the fly.
|-
|<code>/root</code>
|[[Home directory]] for the [[superuser|root]] user.
|-
|<code>/run</code>
|Run-time variable data: Information about the running system since last boot, e.g., currently logged-in users and running [[Daemon (computer software)|daemons]]. Files under this directory must be either removed or truncated at the beginning of the boot process, but this is not necessary on systems that provide this directory as a [[temporary filesystem]] ([[tmpfs]]) (appeared in FHS-3.0 in 2015). 
|-
|<code>/sbin</code>
|Essential system binaries (e.g., [[fsck]], [[init]], [[route (command)|route]]).
|-
|<code>/srv</code>
|Site-specific data served by this system, such as data and scripts for web servers, data offered by [[FTP]] servers, and repositories for [[version control systems]] (appeared in FHS-2.3 in 2004).
|-
|<code>[[/sys]]</code>
|Contains information about devices, drivers, and some kernel features.<ref name="/sys">{{cite web |url=https://refspecs.linuxfoundation.org/FHS_3.0/fhs/ch06.html#sysKernelAndSystemInformation |title=/sys : Kernel and system information virtual filesystem |work=Filesystem Hierarchy Standard 3.0 |access-date=4 June 2017}}</ref>
|-
|<code>/tmp</code>
|[[Temporary folder|Directory for temporary files]] (see also <code>/var/tmp</code>). Often not preserved between system reboots and may be severely size-restricted. 
|-
|<code>/usr</code>
<!-- ##### Please SEE THE TALK PAGE before changing this ##### -->
|''Secondary hierarchy'' for read-only user data; contains the majority of ([[multi-user|multi-]])user utilities and applications.  Should be shareable and read-only.<ref>{{cite web|url=https://refspecs.linuxfoundation.org/FHS_2.3/fhs-2.3.html#THEUSRHIERARCHY|work=Filesystem Hierarchy Standard 2.3|title=Chapter 4. The /usr Hierarchy}}</ref><ref>{{cite web|url=https://refspecs.linuxfoundation.org/FHS_3.0/fhs-3.0.html#purpose18|work=Filesystem Hierarchy Standard 3.0|title=Chapter 4. The /usr Hierarchy, Section 4.1 Purpose}}</ref>
<!-- ##### /usr is NOT anything but the above. This has been rehashed plenty of times before and reverting misled souls like yourself is taking up roughly a third of every edit on this page (another third being the edits of misled souls such as yourself). This time, Wikipedia is right. ##### -->
|-
|<code>/usr/bin</code>
|Non-essential command [[executable|binaries]] (not needed in [[single-user mode]]); for all users.
|-
|<code>/usr/include</code>
|Standard [[header file|include files]].
|-
|<code>/usr/lib</code>
|[[Library (computer science)|Libraries]] for the [[binaries]] in <code>/usr/bin</code> and <code>/usr/sbin</code>.
|-
|<code>/usr/libexec</code>
|Binaries run by other programs that are not intended to be executed directly by users or shell scripts (optional).
|-
|<code>/usr/lib&lt;qual&gt;</code>
|Alternative-format libraries (e.g., <code>/usr/lib32</code> for 32-bit libraries on a 64-bit machine (optional)).
|-
|<code>/usr/local</code>
|''Tertiary hierarchy'' for local data, specific to this host. Typically has further subdirectories (e.g., <code>bin</code>, <code>lib</code>, <code>share</code>).<ref group="NB">Historically and strictly according to the standard, <code>/usr/local</code> is for data that must be stored on the local host (as opposed to <code>/usr</code>, which may be mounted across a network). Most of the time <code>/usr/local</code> is used for installing software/data that are ''not'' part of the standard operating system distribution (in such case, <code>/usr</code> would only contain software/data that ''are'' part of the standard operating system distribution). It is possible that the FHS standard may in the future be changed to reflect this de facto convention.</ref>
|-
|<code>/usr/sbin</code>
|Non-essential system binaries (e.g., [[Daemon (computer software)|daemons]] for various [[network service]]s).
|-
|<code>/usr/share</code>
|Architecture-independent (shared) data.
|-
|<code>/usr/src</code>
|[[Source code]] (e.g., the kernel source code with its header files).
|-
|<code>/usr/X11R6</code>
|[[X Window System]], Version 11, Release 6 (up to FHS-2.3, optional).
|-
|<code>/var</code>
|Variable files: files whose content is expected to continually change during normal operation of the system, such as logs, spool files, and temporary e-mail files.
|-
|<code>/var/cache</code>
|Application cache data. Such data are locally generated as a result of time-consuming I/O or calculation. The application must be able to regenerate or restore the data. The cached files can be deleted without loss of data.
|-
|<code>/var/lib</code>
|State information. Persistent data modified by programs as they run (e.g., databases, packaging system metadata, etc.).
|-
|<code>/var/lock</code>
|Lock files. Files keeping track of resources currently in use.
|-
|<code>/var/log</code>
|Log files. Various logs.
|-
|<code>/var/mail</code>
|Mailbox files. In some distributions, these files may be located in the deprecated <code>/var/spool/mail</code>.
|-
|<code>/var/opt</code>
|Variable data from add-on packages that are stored in <code>/opt</code>.
|-
|<code>/var/run</code>
|Run-time variable data. This directory contains system information data describing the system since it was booted.<ref>{{cite web |url=https://refspecs.linuxfoundation.org/FHS_2.3/fhs-2.3.html#VARRUNRUNTIMEVARIABLEDATA |title=/var/run : Run-time variable data |work=Filesystem Hierarchy Standard 2.3}}</ref><br />
In FHS 3.0, <code>/var/run</code> is replaced by <code>/run</code>; a system should either continue to provide a <code>/var/run</code> directory or provide a symbolic link from <code>/var/run</code> to <code>/run</code> for backwards compatibility.<ref>{{cite web |url=https://refspecs.linuxfoundation.org/FHS_3.0/fhs/ch05s13.html |title=5.13. /var/run : Run-time variable data |work=Filesystem Hierarchy Standard 3.0}}</ref>
|-
|<code>/var/spool</code>
|[[Spooling|Spool]] for tasks waiting to be processed (e.g., print queues and outgoing mail queue).
|-
|<code>/var/spool/mail</code>
|[[Deprecated]] location for users' mailboxes.<ref>{{cite web |title=File System Standard |url=https://refspecs.linuxfoundation.org/FHS_2.3/fhs-2.3.pdf |publisher=Linux Foundation |page=5.11.1}}</ref> 
|-
|<code>/var/tmp</code>
|Temporary files to be preserved between reboots.
|}

== FHS compliance ==
Most [[Linux distribution]]s follow the Filesystem Hierarchy Standard and declare it their own policy to maintain FHS compliance.<ref>[[Red Hat]] reference guide on [https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html-single/Storage_Administration_Guide/index.html#s1-filesystem-fhs file system structure].</ref><ref>[[SuSE Linux]] Enterprise Server Administration, Novell authorized courseware, by Jason W. Eckert, Novell; Course Technology, 2006; {{ISBN|1-4188-3731-8}}, {{ISBN|978-1-4188-3731-0}}.</ref><ref>[[Debian]] policy on [https://www.debian.org/doc/debian-policy/#file-system-hierarchy FHS compliance].</ref><ref>[[Ubuntu]] [https://help.ubuntu.com/community/LinuxFilesystemTreeOverview Linux File system Tree Overview]{{snd}} Community Ubuntu Documentation.</ref> [[GoboLinux]]<ref>{{cite web | title = The Unix tree rethought: an introduction to GoboLinux | url = http://www.gobolinux.org/?page=k5 | author = Hisham Muhammad | date = 9 May 2003 | access-date = 2016-10-04}}</ref> and [[NixOS]]<ref>{{cite conference |last1=Dolstra |first1=E. |last2=Löh |first2=A. |url=https://nixos.org/~eelco/pubs/nixos-icfp2008-final.pdf |title=NixOS: A Purely Functional Linux Distribution |conference-url=http://www.icfpconference.org/icfp2008/ |conference=ICFP 2008: 13th ACM SIGPLAN International Conference on Functional Programming |pages=367–378 |location=Victoria, British Columbia, Canada |date=September 2008}}</ref> provide examples of intentionally non-compliant filesystem implementations.

Some distributions generally follow the standard but deviate from it in some areas. The FHS is a "trailing standard", and so documents common practices at a point in time. Of course, times change, and distribution goals and needs call for experimentation. Some common deviations include:
* Modern Linux distributions include a <code>/sys</code> directory as a [[virtual filesystem]] ([[sysfs]], comparable to <code>/proc</code>, which is a [[procfs]]), which stores and allows modification of the devices connected to the system,<ref>{{cite web |title=5.3 About the /sys Virtual File System |url=http://docs.oracle.com/cd/E37670_01/E41138/html/ol_sysfs.html |website=docs.oracle.com |publisher=Oracle |access-date=8 July 2016 |archive-url=https://web.archive.org/web/20160708193213/https://docs.oracle.com/cd/E37670_01/E41138/html/ol_sysfs.html |archive-date=8 July 2016}}</ref> whereas many traditional [[Unix-like]] operating systems use <code>/sys</code> as a [[symbolic link]] to the [[Kernel (operating system)|kernel]] source tree.<ref>{{cite book |last1=Lehey |first1=Greg |title=The Complete FreeBSD: Documentation from the Source |date=May 2003 |publisher=O'Reilly Media, Incorporated |isbn=9780596005160 |pages=188, 609 |edition=Fourth |url=https://books.google.com/books?id=7Y5kfaRmtKUC}}</ref>
* Many modern Unix-like systems (such as [[FreeBSD]] and [[OpenBSD]]) via their [[Ports collection|ports systems]] install third-party packages into <code>/usr/local</code>, while keeping code considered part of the operating system in <code>/usr</code>.
* Some Linux distributions no longer differentiate between <code>/lib</code> and <code>/usr/lib</code> and have <code>/lib</code> symlinked to <code>/usr/lib</code>.<ref>{{cite web |author1=Allan McRae |title=Arch Linux – News: The /lib directory becomes a symlink |url=https://www.archlinux.org/news/the-lib-directory-becomes-a-symlink/ |website=archlinux.org |access-date=14 December 2019 |archive-url=https://web.archive.org/web/20140909234433/https://www.archlinux.org/news/the-lib-directory-becomes-a-symlink/ |archive-date=9 September 2014 |url-status=live}}</ref>
* Some Linux distributions no longer differentiate between <code>/bin</code> and <code>/usr/bin</code> and between <code>/sbin</code> and <code>/usr/sbin</code>. They may symlink <code>/bin</code> to <code>/usr/bin</code> and <code>/sbin</code> to <code>/usr/sbin</code>. Other distributions choose to consolidate all four, symlinking them to <code>/usr/bin</code>.<ref>{{cite web |author1=Allan McRae |title=Arch Linux – News: Binaries move to /usr/bin requiring update intervention |url=https://www.archlinux.org/news/binaries-move-to-usrbin-requiring-update-intervention/ |website=archlinux.org |access-date=15 December 2019 |archive-url=https://web.archive.org/web/20140910093202/https://www.archlinux.org/news/binaries-move-to-usrbin-requiring-update-intervention/ |archive-date=10 September 2014 |url-status=live}}</ref>

Modern Linux distributions include a <code>/run</code> directory as a [[temporary filesystem]] ([[tmpfs]]), which stores volatile runtime data, following the FHS version 3.0. According to the FHS version 2.3, such data were stored in <code>/var/run</code>, but this was a problem in some cases because this directory is not always available at early boot. As a result, these programs have had to resort to trickery, such as using <code>/dev/.udev</code>, <code>/dev/.mdadm</code>, <code>/dev/.systemd</code> or <code>/dev/.mount</code> directories, even though the device directory is not intended for such data.<ref>{{cite mailing list |url=https://www.mail-archive.com/devel@lists.fedoraproject.org/msg23576.html |title=What's this /run directory doing on my system and where does it come from? |author=Lennart Poettering |date=30 March 2011 |mailing-list=devel@lists.fedoraproject.org}}</ref> Among other advantages, this makes the system easier to use normally with the root filesystem mounted read-only.
For example, below are the changes [[Debian]] made in its 2013 Wheezy release:<ref>{{cite web |url=http://wiki.debian.org/ReleaseGoals/RunDirectory |title=ReleaseGoalsRunDirectory |website=Debian Wiki}}</ref>
* <code>/dev/.*</code> → <code>/run/*</code>
* <code>/dev/shm</code> → <code>/run/shm</code>
* <code>/dev/shm/*</code> → <code>/run/*</code>
* <code>/etc/*</code> (writeable files) → <code>/run/* </code>
* <code>/lib/init/rw</code> → <code>/run</code>
* <code>/var/lock</code> → <code>/run/lock</code>
* <code>/var/run</code> → <code>/run</code>
* <code>/tmp</code> → <code>/run/tmp</code>

== History ==

=== The name of <code>usr</code> ===
<code>/usr</code> originally stood for "user".<ref>{{Cite web |title=/usr |url=https://tldp.org/LDP/Linux-Filesystem-Hierarchy/html/usr.html |access-date=2023-12-10 |website=tldp.org}}</ref> This was an artifact of early Unix programming. Specifically, when [[Ken Thompson]] and [[Dennis Ritchie]] were migrating Unix to a PDP-11, the contents of the <code>/bin</code> and <code>/lib</code> directories, which were to be the first directories mounted on startup and to contain all essentials for the OS to function, became too large to fit on an [[RK05]] disk drive. So they put some of those files on a second RK05, making sure that the first drive contained everything required for loading the second one. The rest of the files were put into the <code>/usr</code> directory.<ref>{{cite web |author-link=Doug McIlroy |author=M. D. McIlroy |date=1987 |url=http://www.cs.dartmouth.edu/~doug/reader.pdf |title=A Research Unix reader: annotated excerpts from the Programmer's Manual, 1971–1986 |id=CSTR 139 |publisher=Bell Labs}}</ref> When they got a third drive, users' files were moved to a new directory named <code>/home</code>.<ref>{{cite mailing list |url=http://lists.busybox.net/pipermail/busybox/2010-December/074114.html |title=Understanding the bin, sbin, usr/bin , usr/sbin split |mailing-list=busybox |first=Rob |last=Landley |date=December 9, 2010}}</ref>

FHS was created as the FSSTND (short for "Filesystem Standard"<ref>{{cite web |url=http://www.ibiblio.org/pub/Linux/docs/fsstnd/old/FSSTND-FAQ |title=FSSTND FAQ page |access-date=2016-05-10}}</ref>), largely based on similar standards for other [[Unix-like]] operating systems. Notable examples are these: the {{mono|hier(7)}} description of file system layout,<ref>{{man|7|hier|FreeBSD}}.</ref> which has existed since the release of [[Version 7 Unix]] (in 1979);<ref>{{man|7|hier|v7}}</ref> the [[SunOS]] {{mono|filesystem(7)}}<ref>[http://www.freebsd.org/cgi/man.cgi?query=filesystem&manpath=SunOS+4.1.3 SunOS 4.1.3 manual page for filesystem(7)], dated 10 January 1988 (from the FreeBSD Man Pages library).</ref> and its successor, the [[Solaris (operating system)|Solaris]] {{mono|filesystem(7)}}.<ref>{{man|7|filesystem|Solaris}}.</ref><ref>{{cite web |url=http://manpages.unixforum.co.uk/man-pages/unix/solaris-10-11_06/5/filesystem-man-page.html |archive-url=https://archive.today/20070704090908/http://manpages.unixforum.co.uk/man-pages/unix/solaris-10-11_06/5/filesystem-man-page.html |url-status=dead |archive-date=2007-07-04 |title=filesystem man page – Solaris 10 11/06 Man Pages |access-date=2011-10-15 }}</ref>

===Release history===

{| class="wikitable"
|-
! Version
! Release date
! Notes
|-
| {{Version|o|1.0}}
| 1994-02-14
| FSSTND<ref>{{cite web |url=http://www.ibiblio.org/pub/Linux/docs/fsstnd/old/fsstnd-1.0/ |title=Index of /pub/Linux/docs/fsstnd/old/fsstnd-1.0/ |publisher=Ibiblio.org |access-date=2012-10-16}}</ref>
|-
| {{Version|o|1.1}}
| 1994-10-09
| FSSTND<ref>{{cite web |url=http://www.ibiblio.org/pub/Linux/docs/fsstnd/old/fsstnd-1.1/ |title=Index of /pub/Linux/docs/fsstnd/old/fsstnd-1.1/ |publisher=Ibiblio.org |access-date=2012-10-16}}</ref>
|-
| {{Version|o|1.2}}
| 1995-03-28
| FSSTND<ref>{{cite web |url=http://www.ibiblio.org/pub/Linux/docs/fsstnd/old/ |title=Index of /pub/Linux/docs/fsstnd/old/ |publisher=Ibiblio.org |access-date=2012-10-16}}</ref>
|-
| {{Version|o|2.0}}
| 1997-10-26
| FHS 2.0 is the direct successor for FSSTND 1.2. Name of the standard was changed to Filesystem Hierarchy Standard.<ref>{{cite web|url=http://www.pathname.com/fhs/announce-2.0.html |title=FHS 2.0 Announcement |publisher=Pathname.com |access-date=2012-10-16}}</ref><ref name="Saborio">{{citation |url=http://www.informatica.co.cr/linux/research/1997/1117.htm |title=FHS 2.0 Announcement |first=Daniel |last=Quinlan |work=BSD, Linux, Unix and The Internet – Research by Kenneth R. Saborio |date=14 March 2012 |orig-year=1997 |publisher=Kenneth R. Saborio |location=San Jose, Costa Rica |access-date=18 February 2016 |archive-url=https://web.archive.org/web/20160305100804/http://www.informatica.co.cr/linux/research/1997/1117.htm |archive-date=5 March 2016 |url-status=dead }}.</ref><ref>{{cite web |url=http://www.ibiblio.org/pub/Linux/docs/fsstnd/ |title=Index of /pub/Linux/docs/fsstnd/ |publisher=Ibiblio.org |access-date=2012-10-16}}</ref>
|-
| {{Version|o|2.1}}
| 2000-04-12
| FHS<ref>{{cite web |url=http://www.pathname.com/fhs/announce-2.1.html |title=FHS 2.1 Announcement |publisher=Pathname.com |access-date=2012-10-16}}</ref><ref>{{cite web |url=http://lists.debian.org/lsb-spec/2000/04/msg00005.html |title=FHS 2.1 is released |publisher=Lists.debian.org |date=2000-04-13 |access-date=2012-10-16}}</ref><ref name="jdiamond">{{cite web |url=http://cs.acadiau.ca/~jdiamond/Acadia-Linux-template-tutorial/resources/fhs-2.1.pdf |title=Filesystem Hierarchy Standard – Version 2.1, Filesystem Hierarchy Standard Group |first=Daniel |last=Quinlan |work=Acadia Linux Tutorials |publisher=Jodrey School of Computer Science, [[Acadia University]] |location=Wolfville, Nova Scotia, Canada |date=12 April 2000 |access-date=18 October 2012 |archive-url=https://web.archive.org/web/20120327075156/http://cs.acadiau.ca/~jdiamond/Acadia-Linux-template-tutorial/resources/fhs-2.1.pdf |archive-date=27 March 2012}}</ref>
|-
| {{Version|o|2.2}}
| 2001-05-23
| FHS<ref name="fhs-2.2">{{cite web |url=http://www.pathname.com/fhs/pub/fhs-2.2.pdf |title=Filesystem Hierarchy Standard – Version 2.2 final Filesystem Hierarchy Standard Group |editor1-first=Rusty |editor1-last=Russell |editor1-link=Rusty Russell |editor2-first=Daniel |editor2-last=Quinlan |work=Filesystem Hierarchy Standard |date=23 May 2001 |access-date=18 February 2016 }}</ref>
|-
| {{Version|o|2.3}}
| 2004-01-29
| FHS<ref name="fhs-2.3">{{cite web |url=https://refspecs.linuxfoundation.org/FHS_2.3/fhs-2.3.pdf |title=Filesystem Hierarchy Standard - Filesystem Hierarchy Standard Group |editor1-first=Rusty |editor1-last=Russell |editor1-link=Rusty Russell |editor2-first=Daniel |editor2-last=Quinlan |editor3-first=Christopher |editor3-last=Yeoh |date=28 January 2004 |access-date=2014-11-29}}</ref>
|-
| {{Version|c|3.0}}
| 2015-05-18
| FHS<ref>{{cite web |url=https://refspecs.linuxfoundation.org/FHS_3.0/fhs-3.0.pdf |title=Filesystem Hierarchy Standard |editor1-first=Christopher |editor1-last=Yeoh |editor2-first=Rusty |editor2-last=Russell |editor3-first=Daniel |editor3-last=Quinlan |publisher=[[The Linux Foundation]] |date=19 March 2015  |access-date=2015-05-20}}</ref>
|-
| colspan="3" | <small>{{Version |l |show=110100}}</small>
|}

== See also ==
*[[Hierarchical file system]]
*[[Unix directory structure]]
*[[Freedesktop.org#Base Directory Specification|XDG Base Directory Specification]]

== Notes ==
{{Reflist|group=NB}}

== References ==

{{Reflist|30em}}

==External links==
* {{Official website|https://wiki.linuxfoundation.org/lsb/fhs|Official Home of the Filesystem Hierarchy Standard (FHS) at The Linux Foundation}}
** [https://refspecs.linuxfoundation.org/fhs.shtml Full specification texts]
* {{cite web| archive-url=https://web.archive.org/web/20211016063611/http://objectroot.org/| title=Objectroot| url=http://objectroot.org/| archive-date=2021-10-16| url-status=usurped}} A proposal for a new filesystem hierarchy, based on object-oriented design principles.
* {{cite web| title=Dotted Standard Filename Hierarchy| archive-url=https://web.archive.org/web/20050508015157/http://ftp.gwdg.de/pub/cLIeNUX/descriptive/DSFH.html| url=http://ftp.gwdg.de/pub/cLIeNUX/descriptive/DSFH.html| archive-date=2005-05-08| url-status=dead}} Yet another very different hierarchy (used in cLIeNUX).
* {{man|7|hier|Linux}}

{{Computer files}}
{{Linux}}

[[Category:Computer standards]]
[[Category:File system directories| ]]
[[Category:Linux]]
[[Category:System administration]]
[[Category:Unix file system technology]]