TIL: Using git check-ignore to debug your .gitignore

• Posted 30 October 2020
• Tagged with git

Here’s a useful thing I learnt today: you can use git check-ignore to debug your gitignore rules and find out why a particular file is (or isn’t) being ignored. It knows all the places where gitignore rules might be defined, and how Git decides between conflicting rules.

By calling git check-ignore --verbose <PATH>, you can see which rule applies to a given path, and where that rule is defined.

There are times I’d have found this very handy!

A few examples:

• If a file is being ignored and you don’t know why, it can show you which line of the .gitignore is causing it to be ignored.

  $ git check-ignore --verbose pictures.zip
  .gitignore:116:*.zip	pictures.zip
  

• If a file isn’t being ignored and you think it should be, it can show you which rule is negating your ignore rule:

  $ git check-ignore --verbose pictures/cats.zip
  pictures/.gitignore:17:!cats.zip	pictures/cats.zip
  

  Notice that it looks in .gitignore files that aren’t in the root of the repo (the sort of thing I often forget about).

• It can even look in your .git/info/exclude, a place for per-clone ignore rules that you don’t want to keep in the repository:

  $ git check-ignore --verbose scripts/alex/downloader.py
  .git/info/exclude:7:scripts/alex/*.py	scripts/alex/downloader.py