,git-prune

#!/bin/sh

set -e

echo "Updating remote state"
git fetch --prune

BRANCHES=$(git branch -vv | grep -e 'gone]' | awk '{ print $1 }')

echo "Branches to delete locally:"
echo $BRANCHES | tr ' ' '\n'

read -p "Is this correct? Confirming will locally delete the listed branches! [Y/n] "
REPLY=${REPLY:-"y"}

(echo $REPLY | grep -Eq ^[Yy]$) && echo $BRANCHES | while read branch; do
    git branch -D $branch
done