🐾MEOW🐾

XDG compliance, or the overwhelming lack thereof

Quick; no time for questions! Open a terminal and run:

ls -A | wc -l

That’s the number of files, folders and other tidbits that have been placed in your $HOME (with or without your blessing). Can you justify that number? Do you even know what is going on there? Personally, I like to keep my home as clean as possible, so let’s take a look and try to do a little spring-cleaning.

A brief background on XDG

XDG or “Cross Desktop Group” (previously known as X Desktop Group) is an ongoing project with the goal of improving UNIX-like operating systems’ interoperability. They have a multitude of software projects and specifications which you can find over at https://freedesktop.org. While their other projects are also interesting, the one we’re focused on during this rant is the “XDG Desktop Base Directories” specification - basedir for short.

At ~800 words, basedir is a short document which provides sensible defaults for the storage location of user-specific files. It also defines some environment variables that can be set to override the default locations. There are seven base directories for the following file types:

File type	Default value	Environment Variable
data files	`$HOME/.local/share`	`XDG_DATA_HOME` / `XDG_DATA_DIRS`
configuration files	`$HOME/.config`	`XDG_CONFIG_HOME` / `XDG_CONFIG_DIRS`
state data	`$HOME/.local/state`	`XDG_STATE_HOME`
non-essential (cached) data	`$HOME/.cache`	`XDG_CACHE_HOME`
runtime files and other file objects	(no default value)	`XDG_RUNTIME_DIR`
executable files	`$HOME/.local/bin`	(no environment variable)

To put this information into context, let’s say we are writing an application called send-bees. It sends bees over TCP/IP to a conveniently preexisting beehive, keeps a record of how many bees were sent in a single bee-sending session, as well as the total number of bees sent. It also keeps a log of your activity per session.

If send-bees respects the basedir, it will behave something like this:

Look for the config file with the default amount of bees to send, beehive address, log policy, etc. under $XDG_CONFIG_HOME/send-bees/config (The file name itself is not specified, so anything goes here, e.g. send-bees.config).
Store the total quantity of bees sent in $XDG_STATE_HOME/send-bees/current.
Open a socket under $XDG_RUNTIME_DIR/send-bees/beehive-socket (once again, file names don’t matter - folders do)
cache any bees sent during the current session in $XDG_CACHE_HOME/send-bees/session, which later may get dumped to the total bees file

There are some benefits to this beyond than having things neatly structured. It also seems to be bothering me enough - to the point I feel it became rant-worthy. Let’s see what advantages we get from complying with the spec:

config files are all in a single directory
$XDG_CONFIG_HOME contains only text files and can sensibly be version-controlled with git
configuring a new device to your liking is as simple as cp -r /backup/.config ~ (or git clone git@host:user/config .config if you are cool)
data and state files are in an expected location, as opposed to ｓｏｍｅｗｈｅｒｅ, depending on how the developer was feeling that day, and can easily be removed/analyzed/backed up
your $XDG_CACHE_HOME can be moved to a tmpfs

What our application should most definitely not do, is to automatically create the $HOME/.send-bees/ directory and dump everything in there, or perhaps even more perplexing, use $XDG_CONFIG_HOME, implying it complies with basedir, but then dump everything, including cache, state, runtime files, etc. into it and call it a day, effectively rendering any kind of version controlling ineffective.

Unfortunately, most applications do not follow basedir, or require setting some environment variables to look in the right places:

Firefox, as well as any forks (e.g. LibreWolf) insist on creating ~/.mozilla/
Thunderbird behaves similarly to Firefox
Android Studio claims ~/.android, even though it allows you to configure what folders it should look in
Dart, Nim, Gradle, and other languages insist in creating their own ~/.{language} folders
Anything Chromium based (that includes every single Electron application) dumps all its files in $XDG_CONFIG_HOME/app/

… and the list goes on.

Many of these have a workaround, but that’s usually it - a hack. Meaning, every time I install a new piece of software, I have to look up if it will fill my ~/.config with junk.

There are tools like xdg-ninja which can help in cleaning up, but it would be great if more applications simply respected the spec.

*sigh*