Understanding .gitignore with git check-ignore

Another day, another obscure yet very useful git command! This time, it’s git check-ignore which helps us to understand why a file is being ignored, or why it’s not if you expect it to be.

To use the function, call git check-ignore -v /path/to/file. The -v flag tells git to also output the matching rule in addition to the file path matched.

Here’s an example where the path matches exactly:

bash
❯ git check-ignore -v node_modules
.gitignore:41:node_modules/	node_modules

And here’s an example where it matches a wildcard:

bash
❯ git check-ignore -v debug.log
.gitignore:3:*.log	debug.log

If you’ve got specific files to exclude from a pattern, it can show those too. If your .gitignore contains *.log as above and you add !debug.log, the debug.log file will be added as we have added a negation with ! to say that it should not be ignored. git check-ignore can show this too:

bash
❯ git check-ignore -v debug.log
.gitignore:4:!debug.log	debug.log