xdg-basedirs

XDG Base Directory Specification defines places where applications/scipts/etc should put configs, cache and data. Specifically, it introduces the $XDG_DATA_HOME, $XDG_CONFIG_HOME, $XDG_DATA_DIRS, $XDG_CONFIG_DIRS, $XDG_CACHE_HOME and $XDG_RUNTIME_DIR environment variables, which (when they're set) should to be used by applications/scripts/etc (instead of hard-coding values like ~/.local/share, ~/.config, /usr/local/share:/usr/share, /etc/xdg, ~/.cache, /run/user/<user-id>, which are typical but not obligatory). However, the XDG Base Directory Specification doesn't say that application/script/etc, you're writing, is allowed to expect that all of these variables are initially set -- it instead states default values that must be used when corresponding variable is unset/empty.

This repository provides two very simple (public domain) helper scripts, which hopefully will save you few minutes if you're writing a shell script that works with ~/.config, ~/.cache, ~/.local/share or /run/user/<uid> directories. Just copy-paste (one or both of) these helper scripts at the beginning of your shell script, or include them using dot command, e.g.:

. xdg-basedirs
. xdg-runtime-dir

Please note, that as purpose of these helper scripts is to set shell variables (XDG_XXX), it is absolutely useless to execute them in usual way (e.g. ./xdg-basedirs or sh xdg-runtime-dir), because neither environment variables, nor shell variables set by child process are visible by the parent process.

So:

1. The xdg-basedirs sets $XDG_DATA_HOME, $XDG_CONFIG_HOME, $XDG_DATA_DIRS, $XDG_CONFIG_DIRS and $XDG_CACHE_HOME variables (i.e. all except $XDG_RUNTIME_DIR) -- if they're unset/empty -- to values specified by the XDG Base Directory Specification as defaults.

   Note, that it doesn't check whether the directories really exist (so that it's your duty to do something like mkdir -p "$XDG_CONFIG_HOME", or better mkdir -p "$XDG_CONFIG_HOME/your-app-name").

2. The xdg-runtime-dir sets $XDG_RUNTIME_DIR variable -- if it is empty/unset. Unlike all other variables from XDG Base Directory Specification, $XDG_RUNTIME_DIR is non-trivial to fill: XDG Base Directory Specification doesn't provide exact default value for it, but instead specifies several very specific requirements. Although xdg-runtime-dir cannot satisfy all these requirements (e.g. purge on user logout), it tries to gracefully handle at least some (e.g. permissions, purge on shutdown, warning message) -- so it can be used as fallback mechanism for systems that may provide $XDG_RUNTIME_DIR themselves.

Both of these helper scripts set shell variables, not environment variables -- i.e. they don't do export -- so newly-set values affect only your script, not the applications/scripts/etc that your script will execute.

For any questions you can connect me via the GitHub.