ruby/tool/git-refresh

#!/bin/sh
set -e

quiet=
branch=

until [ $# = 0 ]; do
    case "$1" in
	--) shift; break;;
	-C|--directory) shift; cd "$1";;
	-C*) cd "${1#-C}";;
	--directory=*) cd "${1#*=}";;
	-q) quiet=1;;
	-b|--branch) shift; branch="$1";;
	-b*) branch="${1#-b}";;
	--branch=*) branch="${1#*=}";;
	-*) echo "unknown option: $1" 1>&2; exit 1;;
	*) break;;
    esac
    shift
done

url="$1"
dir="$2"
shift 2
if [ -d "$dir" ]; then
    echo updating "${dir#*/}" ...
    [ $quiet ] || set -x
    cd "$dir"
    git fetch "$@"
    exec git checkout ${branch:+"$branch"} "$@"
else
    echo retrieving "${dir#*/}" ...
    [ $quiet ] || set -x
    exec git clone "$url" "$dir" "$@"
fi