How can I delete all Git branches which have been merged?

Question

I have many Git branches. How do I delete branches which have already been merged? Is there an easy way to delete them all instead of deleting them one by one?

Answer 1

kuboon's answer missed deleting branches which have the word master in the branch name. The following improves on his answer:

git branch -r --merged | grep -v "origin/master$" | sed 's/\s*origin\///' | xargs -n 1 git push --delete origin

Of course, it does not delete the "master" branch itself :)