Pruning old Git branches

• Posted 27 November 2017
• Tagged with git

Here’s a quick tip for Git users: if you want to delete every local branch that’s already been merged into master, you can run this command:

$ git branch --merged master | egrep -v "(^\*|master|dev)" | xargs git branch --delete

A quick breakdown:

• git branch --merged master gives us a list of branches “whose tips are reachable from the specified commit” — any branch whose final commit has been merged into master. If your main branch has a different name, use that instead of master.

• That gets piped to egrep -v, which excludes any lines which match the pattern. In this case, the pattern filters out branches whose name ends in master or dev. You should adapt this for any long-lived branches in your repo.

• Finally, any branches which remain are passed via xargs to git branch --delete, which deletes the branch.

I originally got the command from a Stack Overflow answer, although I tweaked it when I read the documentation, to more closely match my use case.

If you want to see what branches this will delete without committing to it, run everything before the second pipe — not the xargs bit at the end.

The other command I often use is this one:

$ git fetch origin --prune

If a branch has been deleted in the origin remote, and you had a local branch which was tracking it, the local branch gets deleted as well.

For example: suppose you had a branch called new-feature. You push the branch to GitHub, open a pull request, and later the branch gets merged and deleted through the GitHub web interface. When you do your next fetch with --prune, it’ll clean up the local branch new-feature.

Git branches are very cheap — usually a single file that references a commit hash — so deleting branches won’t save disk space or improve performance. I like to keep my repos neat and tidy, and not have a long branch list to scroll through, which is why I do this. If a long branch list doesn’t bother you, then you can ignore these commands.