Filesystem Hierarchy Standard
The Filesystem Hierarchy Standard (FHS) defines the main directories and their contents in GNU/Linux and other Unix-like computer operating systems.
Overview
The process of developing a standard FileSystem hierarchy began in August 1993 with an effort to restructure the file and directory structure of GNU/Linux. The FSSTND (Filesystem Standard), a filesystem hierarchy standard specific to the GNU/Linux operating system, was released on February 14, 1994. Subsequent revisions were released on October 9, 1994 and March 28, 1995.
In early 1996, the goal of developing a more comprehensive version of FSSTND to address not only GNU/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.
The FHS is maintained by the Free Standards Group, a non-profit organization consisting of major software and hardware vendors, such as HP, IBM and Dell. Still, the vast majority of the GNU/Linux distributions, including those developed by members of the Free Standards Group, do not follow this proposed standard. In particular, paths specifically created by the FHS editors, such as /media/ and /srv/, do not see widespread usage. Some Unix and GNU/Linux systems break with the FHS in favour of a different approach, as in Gobo GNU/Linux.
Directory structure
All files and directories appear under the root_directory “/”, even if stored on different physical devices.
A description of the hierarchy specified in the FHS:
| Directory | Description |
|---|---|
| /bin | Essential user command binaries. |
| /boot | Static files of the boot loader |
| /dev | Device files |
| /etc | Host-specific system configuration |
| /etc/local | Host-specific system configuration for Local binaries |
| /etc/opt | Host-specific system configuration for Add-on application software packages |
| /home | User home directories |
| /lib | Essential shared libraries |
| /libexec | Essential binaries run by other programs (BSD descendant systems only) |
| /lib/modules | Loadable kernel modules (monolitic kernel package only) |
| /lib32 | Essential shared libraries for 32bit binaries (multilib packages only) |
| /media | Mount point for removable media |
| /mnt | Mount point for temporarily mounted filesystem / Mount point for mounting a filesystem temporary |
| /opt | Add-on application software packages |
| /proc | Kernel and process information virtual filesystem (mounted with procfs) |
| /root | Home directory for the root user |
| /run | Run-time variable data / Data relevant to running processes |
| /sbin | Essential system command binaries |
| /srv | Data for services provided by this system |
| /sys | Kernel and system information virtual filesystem (Linux* kernel only; mounted with sysfs) |
| /tmp | Temporary files (mounted with tmpfs) |
| /usr | Secondary hierarchy |
| /usr/bin | Most user command binaries |
| /usr/games | Games and educational binaries |
| /usr/include | Directory for standard include files / Header files included by program languages |
| /usr/lib | Shared libraries |
| /usr/lib/games | Shared libraries for game binaries |
| /usr/lib32 | Shared libraries for 32bit binaries (multilib packages only) |
| /usr/lib32/games | Shared libraries for 32bit game binaries (multilib packages only) |
| /usr/libexec | Binaries run by other programs |
| /usr/local | Local hierarchy (for personal installation only) |
| /usr/local/bin | Local user binaries |
| /usr/local/games | Local games and educational binaries |
| /usr/local/include | Local directory for standard include files / Local header files included by program languages |
| /usr/local/lib | Local shared libraries |
| /usr/local/lib/games | Local shared libraries for game binaries |
| /usr/local/lib32 | Local shared libraries for 32bit binaries (multilib packages only) |
| /usr/local/lib32/games | Local shared libraries for 32bit game binaries (multilib packages only) |
| /usr/local/libexec | Local binaries run by other programs |
| /usr/local/sbin | Local system binaries |
| /usr/local/share | Local architecture-independent data |
| /usr/local/share/doc | Local miscellaneous documentation (documentation packages only) |
| /usr/local/share/games | Local static data files for game binaries |
| /usr/local/share/info | Local primary directory for GNU Info system (texinfo package only) |
| /usr/local/share/man | Local online manuals / Local manual pages |
| /usr/local/share/misc | Local miscellaneous architecture-independent data |
| /usr/local/src | Local source code (source code packages only) |
| /usr/sbin | Non-vital system command binaries |
| /usr/share | Architecture-independent data |
| /usr/share/doc | Miscellaneous documentation (documentation packages only) |
| /usr/share/games | Static data files for game binaries |
| /usr/share/info | Primary directory for GNU Info system (texinfo package only) |
| /usr/share/man | Online manuals / Manual pages |
| /usr/share/misc | Miscellaneous architecture-independent data |
| /usr/src | Source code (source code packages only) |
| /var | Variable data |
| /var/cache | Application cache data |
| /var/crash | Kernel crash dumps (Linux* kernels not supported) |
| /var/games | Variable game data |
| /var/lib | Variable state information |
| /var/lib/misc | Miscellaneous state data |
| /var/local | Variable data for Local binaries |
| /var/lock | Lock files |
| /var/log | Log files |
| /var/mail | User mailbox files |
| /var/opt | Variable data for Add-on application software packages |
| /var/spool | Application spool data |
| /var/tmp | Temporary files preserved between system reboots |
Acknowledgement
This wiki article is based on DebianWiki. We may have removed non-FSDG bits from it.