Create a global gitignore

2020-05-22

If you use git then you should almost certainly create a global gitignore file to ignore things like that should almost never be version controlled, e.g.

• operating system cruft (.DS_Store, Thumbs.db)
• editor tempfiles and non-shared¹ configuration (*.swp, .vscode)
• compiled output (*.o, __pycache__, build/)
• virtual environments and external dependencies (venv, node_modules)
• files you should rename before you commit (Untitled.ipynb)
• tooling caches and output (.mypy_cache)

By default, the global gitignore path is ~/.config/git/ignore on Unix/macOS and %USERPROFILE%\git\ignore on Windows.

The syntax is just like that for .gitignore files. Here’s what mine looks like.

Don’t misuse the repository .gitignore

You might be tempted to put this stuff in a per-repository .gitignore file. I think that’s fine (if you insist) for things that are guaranteed to be created in a working copy of a particular repository (e.g. __pycache__ in a Python project), and thus at particular risk of being merged by collaborators who don’t have a global gitignore like this. But I much prefer to avoid it for OS-specific or editor-specific stuff. Here’s why:

1. These are things you always want to ignore. Recreating and updating this file in every repository is a waste of time.

2. Other users of the repository do not care about the crap created by the operating system or the editor you happen to be using currently, and you don’t care about theirs. This stuff should not be in the shared, version-controlled configuration.

If you follow this advice, repository .gitignore files will contain only of project-specific configuration. They will be shorter and, if you work on a project with lots of collaborators, they will produce less history churn.

Overriding gitignore

If you do want to override your global behavior for some reason then you have a couple of options. You can either manually git add -f the files. Or you can use gitignore’s ! negation syntax in the repository’s .gitignore or .git/info/exclude.

So, for example, if you’ve ignored foo.txt globally, but you really want to commit it in a particular repository, you can git add -f foo.txt or put !foo.txt in a repository .gitignore (which is normally version controlled and shared with collaborators) .git/info/exclude (which is not, and is therefore a truly local configuration).

You don’t need to change core.excludesfile

You’ll see advice to do something like git config --global core.excludesfile ~/.gitignore to tell git where you keep your global gitignore. There is no need to do this unless you object to the perfectly reasonable default location ($XDG_CONFIG_HOME/git/ignore or %USERPROFILE%\git\ignore).