git branch --merged

One can explore git and discover something new every day. One of my recent discoveries is the --merged option of git branch. As the name suggests, it allows you to list all branches which have been merged as of a specified commit. Conveniently, it defaults to the current commit, so by running:

git branch --merged

you can list all the branches which have already been merged up to the current commit.

This happens to be very useful when cleaning up old feature branches after a release. Normally, this would be boring manual process of listing all the branches, but by chaining --merged with a regexp, and another call to git branch:

git branch --merged | grep -E "^\s*[[:digit:]]+_" | xargs git branch -d

We get a nice one-liner deleting all the merged branches with names matching the given pattern (here 123_feature_x). Sure, writing this every time would be worse than the naive approach, but it can be wrapped into a function with a short cryptic name to save on the typing.