How do I configure git to ignore some files locally?

Question

Can I ignore files locally without polluting the global git config for everyone else? I have untracked files that are spam in my git status but I don't want to commit git config changes for every single little random untracked file I have in my local branches.

Answer 1

From the relevant Git documentation:

Patterns which are specific to a particular repository but which do not need to be shared with other related repositories (e.g., auxiliary files that live inside the repository but are specific to one user's workflow) should go into the $GIT_DIR/info/exclude file.

The .git/info/exclude file has the same format as any .gitignore file. Another option is to set core.excludesFile to the name of a file containing global patterns.

Note, if you already have unstaged changes you must run the following after editing your ignore-patterns:

git update-index --assume-unchanged <file-list> 

Note on $GIT_DIR: This is a notation used all over the git manual simply to indicate the path to the git repository. If the environment variable is set, then it will override the location of whichever repo you're in, which probably isn't what you want.

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Edit: Another way is to use:

git update-index --skip-worktree <file-list> 

Reverse it by:

git update-index --no-skip-worktree <file-list> 

Answer 2

Update: Consider using git update-index --skip-worktree [<file>...] instead, thanks @danShumway! See Borealid's explanation on the difference of the two options.

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Old answer:

If you need to ignore local changes to tracked files (we have that with local modifications to config files), use git update-index --assume-unchanged [<file>...].