dirs

A low-level library that provides config/cache/data paths, following the respective conventions on Linux, macOS and Windows (port of the Rust dirs library to LFE/Erlang)

Introduction

• a tiny low-level library with a minimal API
• that provides the platform-specific, user-accessible locations
• for retrieving and storing configuration, cache and other data
• on Linux, Redox, Windows (≥ Vista), macOS and other platforms.

The library provides the location of these directories by leveraging the mechanisms defined by

• the XDG base directory and the XDG user directory specifications on Linux and Redox
• the Known Folder API on Windows
• the Standard Directories guidelines on macOS

Platforms

This library is written in LFE but can be used transparently in Erlang or Elixir projects (that support rebar3) as if it was an Erlang library. It supports Linux and macOS; Windows support is pending.

Usage

Library run by user alice in Erlang:

1> dirs:home().
%% Lin: /home/alice
%% Win: C:\Users\Alice
%% Mac: /Users/Alice

2> dirs:audio().
%% Lin: /home/alice/Music
%% Win: C:\Users\Alice\Music
%% Mac: /Users/Alice/Music

3> dirs:config().
%% Lin: /home/alice/.config
%% Win: C:\Users\Alice\AppData\Roaming
%% Mac: /Users/Alice/Library/Application Support

4> dirs:executable().
%% Lin: /home/alice/.local/bin
%% Win: undefined
%% Mac: undefined

In LFE:

lfe> (dirs:home)
;; Lin: /home/alice
;; Win: C:\Users\Alice
;; Mac: /Users/Alice

lfe> (dirs:audio)
;; Lin: /home/alice/Music
;; Win: C:\Users\Alice\Music
;; Mac: /Users/Alice/Music

lfe> (dirs:config)
;; Lin: /home/alice/.config
;; Win: C:\Users\Alice\AppData\Roaming
;; Mac: /Users/Alice/Library/Application Support

lfe> (dirs:executable)
;; Lin: /home/alice/.local/bin
;; Win: undefined
;; Mac: undefined

Note that all dirs:* functions support an additional arity, allowing one to append one or more path segments to the given directory:

1> dirs:home("lab").
"/Users/oubiwann/lab"
2> dirs:home(["lab", "lfe"]).
"/Users/oubiwann/lab/lfe"
3> dirs:video(["Conferences", "EUC", 2019, drafts]).
"/Users/oubiwann/Movies/Conferences/EUC/2019/drafts"
4> dirs:cache([2023,11,27,d34db33fcafe,0,1,5,12,42]).
"/Users/oubiwann/Library/Caches/2023/11/27/d34db33fcafe/0/1/5/12/42"

Design Goals

• The dirs library is a low-level one, designed to provide the paths to standard directories as defined by operating systems rules or conventions.
  If your requirements are more complex, e. g. computing cache, config, etc. paths for specific applications or projects, consider writing something higher-level that uses dirs -- let us know if you do, and we'll link to it!
• This library does not create directories or check for their existence. The library only provides information on what the path to a certain directory should be.
  How this information is used is a decision that developers need to make based on the requirements of each individual application.
• This library is intentionally focused on providing information on user-writable directories only, as there is no discernible benefit in returning a path that points to a user-level, writable directory on one operating system, but a system-level, read-only directory on another.
  The confusion and unexpected failure modes of such an approach would be immense.
  • executable is specified to provide the path to a user-writable directory for binaries.
    As such a directory only commonly exists on Linux, it returns undefined on macOS and Windows.
  • font is specified to provide the path to a user-writable directory for fonts.
    As such a directory only exists on Linux and macOS, it returns undefined on Windows.
  • runtime is specified to provide the path to a directory for non-essential runtime data. It is required that this directory is created when the user logs in, is only accessible by the user itself, is deleted when the user logs out, and supports all filesystem features of the operating system.
    As such a directory only commonly exists on Linux, it returns undefined on macOS and Windows.

Features

Function name	Value on Linux/Redox	Value on Windows (not yet impl)	Value on macOS
dirs:home	$HOME	{FOLDERID_Profile}	$HOME
dirs:cache	$XDG_CACHE_HOME or $HOME/.cache	{FOLDERID_LocalAppData}	$HOME/Library/Caches
dirs:config	$XDG_CONFIG_HOME or $HOME/.config	{FOLDERID_RoamingAppData}	$HOME/Library/Application Support
dirs:config_local and dirs:config-local	$XDG_CONFIG_HOME or $HOME/.config	{FOLDERID_LocalAppData}	$HOME/Library/Application Support
dirs:data	$XDG_DATA_HOME or $HOME/.local/share	{FOLDERID_RoamingAppData}	$HOME/Library/Application Support
dirs:data_local and dirs::data-local	$XDG_DATA_HOME or $HOME/.local/share	{FOLDERID_LocalAppData}	$HOME/Library/Application Support
dirs:executable	$XDG_BIN_HOME or $HOME/.local/bin	undefined	undefined
dirs:preference	$XDG_CONFIG_HOME or $HOME/.config	{FOLDERID_RoamingAppData}	$HOME/Library/Preferences
dirs:runtime	$XDG_RUNTIME_DIR or undefined	undefined	undefined
dirs:state	$XDG_STATE_HOME or $HOME/.local/state	undefined	undefined
dirs:audio	XDG_MUSIC_DIR or undefined	{FOLDERID_Music}	$HOME/Music
dirs:desktop	XDG_DESKTOP_DIR or undefined	{FOLDERID_Desktop}	$HOME/Desktop
dirs:document	XDG_DOCUMENTS_DIR or undefined	{FOLDERID_Documents}	$HOME/Documents
dirs:download	XDG_DOWNLOAD_DIR or undefined	{FOLDERID_Downloads}	$HOME/Downloads
dirs:font	$XDG_DATA_HOME/fonts or $HOME/.local/share/fonts	undefined	$HOME/Library/Fonts
dirs:picture	XDG_PICTURES_DIR or undefined	{FOLDERID_Pictures}	$HOME/Pictures
dirs:public	XDG_PUBLICSHARE_DIR or undefined	{FOLDERID_Public}	$HOME/Public
dirs:template	XDG_TEMPLATES_DIR or undefined	{FOLDERID_Templates}	undefined
dirs:video	XDG_VIDEOS_DIR or undefined	{FOLDERID_Videos}	$HOME/Movies

License

Apache License, Version 2.0

Copyright © 2023-2024, Duncan McGreggor oubiwann@gmail.com.