# XDG - Base Directory Specification

XDG environment variables are not set by default on Debian, as per the XDG Base Directory Specification, which defines them as optional. If unset, applications fall back to default paths like $HOME/.config, $HOME/.local/share, and $HOME/.cache.

To ensure XDG variables are set system-wide, define them in /etc/security/pam_env.conf using the DEFAULT syntax, which is reliably loaded during graphical login and session initialization:

conf_print_xdg() {
cat <<EOF
XDG_CONFIG_HOME DEFAULT=@{HOME}/.config
XDG_CACHE_HOME DEFAULT=@{HOME}/.cache
XDG_DATA_HOME DEFAULT=@{HOME}/.local/share
XDG_STATE_HOME DEFAULT=@{HOME}/.local/state
EOF
}
conf_print_xdg | sudo tee /etc/security/pam_env.conf

Alternatively, for shell environments, set them in /etc/profile.d/xdg.sh:

conf_print_xdg() {
cat <<EOF
export XDG_CONFIG_HOME="${XDG_CONFIG_HOME:-$HOME/.config}"
export XDG_CACHE_HOME="${XDG_CACHE_HOME:-$HOME/.cache}"
export XDG_DATA_HOME="${XDG_DATA_HOME:-$HOME/.local/share}"
export XDG_STATE_HOME="${XDG_STATE_HOME:-$HOME/.local/state}"
EOF
}
conf_print_xdg | sudo tee /etc/profile.d/xdg.sh

    ⚠️ Note: Variables set in shell files like .zshrc or .profile may not be
    available during graphical sessions (e.g., via a display manager). Use PAM
    for system-wide, session-aware consistency.

## Base

The intended use-case for BaseDirectories is to query the paths of user-
invisible standard directories that have been defined according to the
conventions of the operating system the library is running on.

If you want to compute the location of cache, config or data folders for your
own application or project, use ProjectDirectories instead.

| Type | Purpose    | XDG Environment Variable | Linux / BSD                          | MacOS                             |
| ---- | ---------- | ------------------------ | ------------------------------------ | --------------------------------- |
| Base | home       | HOME                     | $HOME                                | $HOME                             |
| Base | cache      | XDG_CACHE_HOME           | $XDG_CACHE_HOME or $HOME/.cache      | $HOME/Library/Caches              |
| Base | config     | XDG_CONFIG_HOME          | $XDG_CONFIG_HOME or $HOME/.config    | $HOME/Library/Application Support |
| Base | data       | XDG_DATA_HOME            | $XDG_DATA_HOME or $HOME/.local/share | $HOME/Library/Application Support |
| Base | dataLocal  | XDG_DATA_HOME            | $XDG_DATA_HOME or $HOME/.local/share | $HOME/Library/Application Support |
| Base | executable | XDG_BIN_HOME             | $XDG_BIN_HOME or $HOME/.local/bin    | null                              |
| Base | preference | XDG_CONFIG_HOME          | $XDG_CONFIG_HOME or $HOME/.config    | $HOME/Library/Preferences         |
| Base | runtime    | XDG_RUNTIME_DIR          | $XDG_RUNTIME_DIR or null             | null                              |

## User

The intended use-case for UserDirectories is to query the paths of user-facing
standard directories that have been defined according to the conventions of the
operating system the library is running on.

| Type | Purpose  | XDG Environment Variable | Linux / BSD                                      | MacOS               |
| ---- | -------- | ------------------------ | ------------------------------------------------ | ------------------- |
| User | audio    | XDG_MUSIC_DIR            | $XDG_MUSIC_DIR                                   | $HOME/Music         |
| User | desktop  | XDG_DESKTOP_DIR          | $XDG_DESKTOP_DIR                                 | $HOME/Desktop       |
| User | document | XDG_DOCUMENTS_DIR        | $XDG_DOCUMENTS_DIR                               | $HOME/Documents     |
| User | download | XDG_DOWNLOAD_DIR         | $XDG_DOWNLOAD_DIR                                | $HOME/Downloads     |
| User | font     | XDG_DATA_HOME            | $XDG_DATA_HOME/fonts or $HOME/.local/share/fonts | $HOME/Library/Fonts |
| User | picture  | XDG_PICTURES_DIR         | $XDG_PICTURES_DIR                                | $HOME/Pictures      |
| User | public   | XDG_PUBLICSHARE_DIR      | $XDG_PUBLICSHARE_DIR                             | $HOME/Public        |
| User | template | XDG_TEMPLATES_DIR        | $XDG_TEMPLATES_DIR                               | null                |
| User | video    | XDG_VIDEOS_DIR           | $XDG_VIDEOS_DIR                                  | $HOME/Movies        |

## Project

The intended use-case for ProjectDirectories is to compute the location of
cache, config or data folders for your own application or project, which are
derived from the standard directories.

| Type    | Purpose    | XDG Environment Variable       | Linux / BSD                                         | MacOS                                            |
| ------- | ---------- | ------------------------------ | --------------------------------------------------- | ------------------------------------------------ |
| Project | cache      | XDG_CACHE_HOME/<project_path>  | $XDG_CACHE_HOME or $HOME/.cache/<project_path>      | $HOME/Library/Caches/<project_path>              |
| Project | config     | XDG_CONFIG_HOME/<project_path> | $XDG_CONFIG_HOME or $HOME/.config/<project_path>    | $HOME/Library/Preferences/<project_path>         |
| Project | data       | XDG_CONFIG_HOME/<project_path> | $XDG_CONFIG_HOME or $HOME/.config/<project_path>    | $HOME/Library/Application Support/<project_path> |
| Project | dataLocal  | XDG_DATA_HOME/<project_path>   | $XDG_DATA_HOME or $HOME/.local/share/<project_path> | $HOME/Library/Application Support/<project_path> |
| Project | preference | XDG_DATA_HOME/<project_path>   | $XDG_DATA_HOME or $HOME/.local/share/<project_path> | $HOME/Library/Application Support/<project_path> |
| Project | runtime    | XDG_RUNTIME_DIR/<project_path> | $XDG_RUNTIME_DIR/<project_path>                     | null                                             |