GIT: Delete all (except specific) branches from your local repo

delete_multiple_branches.sh

#!/bin/bash
function exit_if_nothing {
    if [ -z "$list" ]; then
        echo "Nothing to delete"
        exit 0
    fi
}
list=`git branch --list | cat | grep -v '\*' | grep -v "\master\b"`
exit_if_nothing
for i in $*; do
   list=`grep -v "\b$i\b" <<< $list`
done
list=`echo $list | paste -s -d " " -`
exit_if_nothing
git branch -D $list

Usage:

$ delete_multiple_branches

This will delete all the branches except master and your current branch.

$ delete_multiple_branches branch1 branch2

This will delete all the branches except master, branch1, branch2 and your current branch.