Help keeping ~/.config/emacs clean

The default paths used to store configuration files and persistent data are not consistent across Emacs packages. This isn’t just a problem with third-party packages but even with built-in packages.

Some packages put these files directly in user-emacs-directory or $HOME or in a subdirectory of either of the two or elsewhere. Furthermore sometimes file names are used that don’t provide any insight into what package might have created them.

This package sets out to fix this by changing the values of path variables to put configuration files in no-littering-etc-directory (defaulting to “etc/” under user-emacs-directory, thus usually “$HOME/.config/emacs/etc/”) and persistent data files in no-littering-var-directory (defaulting to “var/” under user-emacs-directory, thus usually “$HOME/.config/emacs/var/”), and by using descriptive file names and subdirectories when appropriate. This is similar to a color-theme; a “path-theme” if you will.

We still have a long way to go until most built-in and many third-party path variables are properly “themed”. Like a color-theme, this package depends on user contributions to accomplish decent coverage. Pull requests are highly welcome (but please follow the conventions described below and in the pull request template).

This package does not automatically migrate existing files to their new locations, but unless you want to, you also do not have to do it completely by hand. The contributed migrate.org provides some guidance and tools to help with the migration.

Usage

Load the feature no-littering as early as possible in your init file. Make sure you load it at least before you change any path variables using some other method.

(require 'no-littering)

If you would like to use base directories different from what no-littering uses by default, then you have to set the respective variables before loading the feature.

(setq no-littering-etc-directory
      (expand-file-name "config/" user-emacs-directory))
(setq no-littering-var-directory
      (expand-file-name "data/" user-emacs-directory))
(require 'no-littering)

Suggested Settings

Auto-save, backup and undo-tree files

Creating backups increases the odds that secret information, which would otherwise never be stored in clear text, is written to disk. Likewise backups increase the odds that leaked secrets persist longer.

This topic is beyond the scope of this documentation, but as the author of this package, I want to at least ensure that its use does not make matters worse.

For that reason, simply loading no-littering, does not theme the built-in backup and auto-save functionality, and the third-party undo-tree package.

A function no-littering-theme-backups is provided, which does theme these features. Before calling that function from your init files, you should read its docstring and implementation.

Recent files

If you use recentf then you might find it convenient to exclude all of the files in the no-littering directories using something like the following.

(require 'recentf)
(add-to-list 'recentf-exclude
             (recentf-expand-file-name no-littering-var-directory))
(add-to-list 'recentf-exclude
             (recentf-expand-file-name no-littering-etc-directory))

Saved customizations

Emacs will save customizations into your init.el file by default. If you don’t want that, you might want to store them in a sibling file or even in the etc/ directory:

(setq custom-file (expand-file-name "custom.el" user-emacs-directory))
;; or
(setq custom-file (no-littering-expand-etc-file-name "custom.el"))

Native compilation cache

When using Emacs 29, the location of the native compilation cache can be changed using a function, preferably in early-init.el:

(when (fboundp 'startup-redirect-eln-cache)
  (startup-redirect-eln-cache
   (convert-standard-filename
    (expand-file-name  "var/eln-cache/" user-emacs-directory))))

Conventions

(A) File names

1. File names are based on the name of the respective Emacs lisp variables and the name of the respective Emacs package.
2. The name of the respective Emacs package should serve as the prefix of the file name, unless the file is in a subdirectory in which case the name of the subdirectory serves as the prefix.
3. If the name of the package and the prefix of the variable do not match, then we prefer the name of the package.
4. If the name of a path variable ends with -file, -default-file, -directory, -default-directory, or something similar, then that suffix is usually dropped from the file name.
5. If applicable, the appropriate extension is added to the file name so that files are visited using the appropriate major-modes and also to provide a hint about the kind of data stored in the file. E.g., if a file contains an S-expression, then the suffix should be .eld.

   (In the past we used .el instead, because .eld did not exist yet. Many themed files still use the .el suffix, and I do not plan to update them to the preferred .eld suffix any time soon. But for newly themed files .eld should be preferred in most cases.)

(B) File location and subdirectories

1. If a package has only one data file, then that is usually placed in no-littering-var-directory itself. Likewise if a package has only one config file, then that is placed in no-littering-etc-directory itself.
2. If a package has multiple data (or config files), then those files are placed in a subdirectory of no-littering-var-directory (or no-littering-etc-directory).
3. If a subdirectory is used for a package’s data (or config) file variables, then the name of the directory should match the name of the package in most cases. The subdirectory name may serve as the package prefix of the file name.
4. If a package provides a “framework” for other packages to use, then we may reuse its directories for other packages that make use of that framework or otherwise “extend” the “main package”. E.g., we place all helm related files in helm/.
5. If a package only defines a single variable that specifies a data (or config) directory, then the directory name should nevertheless be just the package name. E.g., the path used for sx-cache-directory from the sx package is sx/cache/, not sx-cache/.
6. However if the name of the directory variable implies that the package won’t ever define any data (or config) files that won’t be placed in that directory, then we use a top-level directory. E.g. when the name of the variable is <package>-directory, in which case we would use just <package>/ as the path.

(C) Ordering and alignment

1. The code that sets the values of themed variables is split into two groups. The first group sets the value of variables that belong to packages that are part of Emacs, and the second group is used for variables that are defined by packages that are not part of Emacs.
2. Each of these lists is sorted alphabetically (usually by variable name). Please keep it that way.
3. We attempt to align the value forms inside different setq forms. If the symbol part for a particular variable is too long to allow doing so, then don’t worry about it and just break the alignment. If it turns out that this happens very often, then we will adjust the alignment eventually.

(D) Commit messages

1. Please theme each package using a separate commit and use commit messages of the form <package>: Theme <variable>.
2. If a package has several path variables, then you should theme them all in one commit.
3. If the variable names do not fit nicely on the summary line, then use a message such as:

   foo: Theme variables
   
   Theme `foo-config-file', `foo-cache-directory',
   and `foo-persistent-file'.
       

4. When appropriate add statements like the following to the commit message:
   • This file is used to store an s-expression.
   • This file is used to store raw text.
   • This is the only configuration/data file of the package.
   • This package does/doesn’t take care of creating the containing directory if necessary. (If the package does not do it, then you should also fix that and submit an upstream pull request.)
5. If you are uncertain, then be explicit about it by adding a comment to the pull-request.