Prompt for and delete local branches that are tracking deleted remote branches

git-prune-local.zsh

#!/usr/bin/env zsh

# Remove no longer existing remote branches.
git fetch --prune &> /dev/null

# Find all branches with a deleted remote branch.
branches=(${(@f)$(git branch -vv | grep ": gone]" | awk '{ print $1 }')})

if [[ $#branches == 0 ]]; then
  print -P "No pruneable local branches found."
  exit 0
fi

print -P "%F{cyan}The following local branches will be deleted:\n%B%F{red}"
print -f "%s\n" ${branches[@]}
print -nP "%b%F{cyan}\nContinue (y/n)?%f "
read -q "confirmation?"

if [[ $confirmation == "y" ]]; then
  echo
  git branch -D ${branches[@]}
fi