Emacs .gitignore template

Emacs produces three distinct kinds of temporary file and this template covers all three. Files ending in a tilde are backups of the previous saved version, written next to the original every time you save unless you configure the editor otherwise. Files wrapped in hash characters are auto saves, written periodically so a crash does not lose work. Files starting with .# are lock files, and they are symbolic links whose target encodes the user and host currently editing that file.

That last detail is worth noting. A lock file is not a normal file at all, and a committed one is a dangling symbolic link pointing at a username and hostname that meant something on one machine for a few minutes. Configuring the editor to put backups and auto saves in a central directory removes the problem at the source, which is what most people eventually do.

*.elc is compiled Lisp bytecode. It is produced from the .el file next to it and it is version specific: bytecode compiled by one editor version can fail to load in another. A stale .elc that is newer than its source will also be loaded in preference to it, which produces the confusing case where editing the source changes nothing.

auto-save-list holds the index of auto save files for a session, and tramp holds cached connection state for remote editing, including the hosts and paths you connected to. /.emacs.desktop and its lock file save the set of buffers open in a session, restored on next start.

The remaining rules cover per project tooling: flycheck_*.el are temporary copies the syntax checker writes for linting, .projectile is a project definition file, .dir-locals.el holds directory scoped variables, and .org-id-locations is an index of note identifiers. .dir-locals.el is the one to reconsider, since a team that shares directory local settings deliberately may want it tracked.