Here’s a script that will delete all local branches that have been squash merged into master:
git checkout -q master && git for-each-ref refs/heads/ "--format=%(refname:short)" | while read branch; do mergeBase=$(git merge-base master $branch) && [[ $(git cherry master $(git commit-tree $(git rev-parse "$branch^{tree}") -p $mergeBase -m _)) == "-"* ]] && git branch -D $branch; done
If you want to run a dry run, you can instead run this:
git checkout -q master && git for-each-ref refs/heads/ "--format=%(refname:short)" | while read branch; do mergeBase=$(git merge-base master $branch) && [[ $(git cherry master $(git commit-tree $(git rev-parse "$branch^{tree}") -p $mergeBase -m _)) == "-"* ]] && echo "$branch is merged into master and can be deleted"; done
You can then setup an alias like this:
alias gprunesquashmerged='git checkout -q master && git for-each-ref refs/heads/ "--format=%(refname:short)" | while read branch; do mergeBase=$(git merge-base master $branch) && [[ $(git cherry master $(git commit-tree $(git rev-parse "$branch^{tree}") -p $mergeBase -m _)) == "-"* ]] && git branch -D $branch; done'
Source:
https://github.com/not-an-aardvark/git-delete-squashed