#!/bin/bash

_usage() {
    echo "Usage: git shortrev <committish>" 1>&2
    exit 1
}

_shortrev() {
    commit="${1:-HEAD}"
    name="$(git name-rev --name-only "$commit")";
    rev="$(git rev-parse --short "$commit")";
    echo "$name@$rev";
}

case $# in
    1 ) _shortrev "$1";;
    0 ) _shortrev;;
    * ) _usage
esac