This script is for cleaning up merged branches on remote, it will only check merged and also outputs relevant information, then prompts for action. It also prunes the origin if deletes were made.

git_branch_cleaner.sh

#!/bin/bash

count=0
# grab remote merged branches, ignoring master and HEAD
for x in `git branch --merged master -r --column | grep -v HEAD | grep -v master`; do
  branch="${x/origin\//}"
  mod=$(git show --pretty=format:"%Cgreen%ci %Cblue%cr%Creset" $x | head -n 1)
  # get the number of commits the remote branch is behind/ahead of master
  set -- $(git rev-list --left-right --count origin/$branch...origin/master)
  ahead=$1
  behind=$2
  printf "\033[0;35m$branch\033[0m\n"
  echo "Last Commit: "$mod
  echo "Commits behind: " $behind " Ahead: " $ahead
  read -p "Delete? [Y/n/q]" -n1 option
  case "$option" in
    ""|y|Y)
      count=$((count+1))
      git push origin :$branch
      ;;
    n|N)
      echo
      continue
      ;;
    q|Q)
      break
      ;;
  esac
done

if [ "$count" -gt 0 ]; then
  echo
  echo "Pruning origin."
  git remote prune origin
fi