Cleaning up old branches from a Git repo

gistfile1.sh

# Update local remote refs, and delete all local remote refs that have been 
# deleted on Github:

$ git fetch -p

# Switch to a primary branch (i.e. 'api' or 'master'), you will use this branch
# to find all merged branches that you will delete:

$ git checkout api

# Find all branches that have been merged with this branch, and delete them.
# NOTE: This might result in your master branch being deleted when run from
# another branch already merged with master. This may or may not be a bad thing
# for you - be aware and decide if you want to avoid that (note that you can
# easily re-checkout the master branch to match your remote):

$ git branch --merged | grep -v "\*" | xargs -n 1 git branch -d