Git function to delete all branches merged to default branch

gistfile1.txt

_gbclean () {
  default_branch=$( git remote show origin | sed -n '/HEAD branch/s/.*: //p')
  git checkout "${default_branch}" && git pull && \
    for branch in $(git branch -l | grep -v -e "${default_branch}" ); do
        git branch -d $branch
    done
}

alias gbclean='_gbclean'