git-prune-remote-branches

#!/usr/bin/env bash
# https://gist.github.com/schacon/942899

MAIN_BRANCH=master
REMOTE=origin
IGNORE_BRANCHES="$MAIN_BRANCH"

function print_merged_branches() {
  git branch -r --merged $REMOTE/$MAIN_BRANCH | grep $REMOTE | egrep -v ">|$IGNORE_BRANCHES" | cut -d/ -f2-
}

if [ "$1" == '-f' ]; then
  print_merged_branches | xargs git push origin --delete
  exit
fi

echo "Branches are merged into $REMOTE/$MAIN_BRANCH:"
print_merged_branches
echo
echo "Rerun this command with -f flag to remove them from $REMOTE."