diff a branch to a base branch

git-diff-to.sh

#!/usr/bin/env bash

help() {
    cat <<EOS
$0 [-h | --help] [base] [head]

Diff current branch (or [head], if passed) to [base]
EOS
}

POSITIONAL=()
while [[ $# -gt 0 ]]
do
    key="$1"

    case $key in
        -h|--help)
        help
        exit 1
        ;;

        *)    # unknown option
        POSITIONAL+=("$1") # save it in an array for later
        shift # past argument
        ;;
    esac
done
set -- "${POSITIONAL[@]}" # restore positional parameters

. "$(git --exec-path)/git-sh-setup"

base_branch="$1"
head_branch="${2:-HEAD}"

echo "$base_branch"
echo "$head_branch"

exec git diff $(git merge-base "$base_branch" "$head_branch").."$head_branch"