Directory Standards

This is a short overview of standards for directories.

TODO: Overlaps with Configuration Locations.

Unix based

There are 2 important standards, which have their own scope:

FHS

The Filesystem Hierarchy Standard (FHS) defines the general directory layout of a computer system. It is currently maintained by The Linux Foundation at https://wiki.linuxfoundation.org/lsb/fhs. Before it was at http://www.pathname.com/fhs/ maintained by the Linux Standard Base (LSB) workgroup of freestandards.org.

The different BSD variants are no longer part. They use only

man hier(7)

.

XDG

The former X Desktop Group is today known as Freedesktop.org. Its XDG Base Directory Specification defines some rules for the home directory.

XDG variable	Default	Notes
$XDG_CONFIG_HOME	$HOME/.config	the base directory relative to which user specific configuration files should be stored.
$XDG_CONFIG_DIRS	/etc/xdg	the colon ':' seperated preference-ordered set of base directories to search for configuration files in addition to $XDG_CONFIG_HOME
$XDG_DATA_HOME	$HOME/.local/share	the base directory relative to which user specific data files should be stored.
$XDG_DATA_DIRS	usr/local/share/:/usr/share/	the colon ':' seperated preference-ordered set of base directories to search for data files in addition to $XDG_DATA_HOME
$XDG_CACHE_HOME	$HOME/.cache	the base directory relative to which user specific non-essential data files should be stored.
$XDG_RUNTIME_DIR	If it is not set applications should fall back to a replacement directory with similar capabilities and print a warning message.	Applications should use this directory for communication and synchronization purposes and should not place larger files in it, since it might reside in runtime memory and cannot necessarily be swapped out to disk...

Partly the home directory uses similar subdirectories as the system has, some with the same name like /usr/share vs. ~/.share, others with a different name like /etc vs. ~/.config. This will allow among others a fallback: if no value is found in ~/.config check /etc for the system wide default.

MS-DOS based

The KNOWNFOLDERIDs replaced in Vista the former constant special item ID list (CSIDL). .