git-delete-merged-branches

#!/bin/bash

branch="$1"
remotes="origin gitlab github"

if [[ -z "$branch" ]]; then
   for remote in $remotes; do
      if $(git remote get-url $remote &> /dev/null); then
          branch=$(git remote show $remote | grep "HEAD branch:" | awk '{print $3;}')
          break
      fi
    done
fi

[ -z "$branch" ] && echo "Unable to find default branch" && exit 1

echo "Deleting branches merged into $branch"

for to_delete in $(git branch --merged $branch | grep -v "^\*" | grep -v "$branch"); do
    echo "Deleting $to_delete ($(git log -1 --pretty=reference $to_delete)"
    git branch --quiet -d "$to_delete"
done