Remove local branches that have been merged in the remote (with confirmation)

git-remove-remote-merged.sh

#!/usr/bin/env bash

# Protip! You can add this to your gitconfig as a custom git command:
# 1. open `~/.gitconfig`
# 2. if the [alias] block doesn't exist, create it
# 3. add the following line:
#       remove-remote-merged = !git-remove-remote-merged
# 4. Save the file, now you can do:
#       git remove-remote-merged

if [[ "$OSTYPE" == "darwin"* ]]; then
  AWK="gawk"
else
  AWK="awk"
fi

# Based on https://stackoverflow.com/a/33548037
git fetch -p >/dev/null 2>&1

branches_to_delete=$(git branch -vv | "$AWK" '{print $1,$4}' | grep 'gone]' | "$AWK" '{print $1}')

if [ -z "$branches_to_delete" ]; then
  echo "Nothing to delete, no branches exist locally that have been merged in remote."
else
  echo "Would delete the following branches which are merged in the remote base branch:"

  printf -- '- %s\n' ${branches_to_delete[@]}
  echo
  read -p "Are you sure? [Yn] " -r
  echo

  if [[ -z $REPLY || $REPLY =~ ^[Yy]$ ]]; then
    for branch in $branches_to_delete; do git branch -D $branch; done
  else
    echo "Did not receive confirmation to delete branches, skipping."
  fi
fi