git-clone-branches

#!/bin/sh
#
#    Copyright 2010 Joel Weinberger
#
#    This program is free software: you can redistribute it and/or modify it
#    under the terms of the GNU General Public License as published by the Free
#    Software Foundation, either version 3 of the License, or (at your option)
#    any later version.
#
#    This program is distributed in the hope that it will be useful, but WITHOUT
#    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
#    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
#    more details.
#
#    You should have received a copy of the GNU General Public License along
#    with this program.  If not, see <http://www.gnu.org/licenses/>.
#
# This script allows for 'clones' of repositories but only specifying some
# remote branches to clone. This is useful with repositories that have many
# branches with very different overlap so that cloning all branches is very
# expensive. For example, if you have a giant code project in branch 'foo', but
# only want to work on the TeX files in the 'paper' branch, this might be a good
# option.

set -e

USAGE="git-clone-branches [-t track branch]... [-b checkout branch] [-r remote name] <repository> <directory>"

BRANCHES=""
CHECKOUT=""
REMOTENAME="origin"

while getopts ":ht:b:r:" opt; do
	case $opt in
		h)
			echo "usage: $USAGE"
			echo ""
			echo "git-clone-branches allows a user to clone only a subset of branches from a"
			echo "repository. If no branches are specified, defaults to 'master'. If no "
			echo "checkout branch is specified, the first listed branch is checked out."
			echo ""
			echo "-h                    shows this help message"
			echo "-t <branch name>      specifies a remote branch to clone"
			echo "-b <branch name>      specifies a branch to checkout after partial clone"
			echo "-r <remote name>      name to give remote (default is 'origin')"
			exit 0
			;;
		t)
			BRANCHES="$BRANCHES -t $OPTARG"
			# if no checkout branch has been specified yet, use this branch as
			# it must be the first remote branch specified.
			if [ ! $CHECKOUT ]; then
				CHECKOUT="$OPTARG"
			fi
			;;
		b)
			CHECKOUT="$OPTARG"
			;;
		r)
			REMOTENAME="$OPTARG"
			;;
		:)
			echo "option -$OPTARG requires an argument" >&2
			echo "usage: $USAGE" >&2
			exit 1
			;;
		\?)
			echo "unknown option: -$OPTARG" >&2
			echo "usage: $USAGE" >&2
			exit 1
			;;
	esac
done

# If no branches are specified, default to master branch.
if [ ! "$BRANCHES" ]; then
	BRANCHES="-t master"

	# If no checkout branch has been specified, then it should also be set to
	# master.
	if [ ! $CHECKOUT ]; then
		CHECKOUT="master"
	fi
fi

# Shift the arguments past all of the options
shift $(($OPTIND - 1))

# Make sure that there are the correct number of non-option arguments.
if [ $# != 2 ]; then
	echo "You must provide a repository to clone and a directory to clone to." >&2
	echo "" >&2
	echo "usage: $USAGE" >&2
	exit 1
fi

REPO=$1
DIR=$2

# Create the requested directory if it doesn't exist.
if [ ! -e $DIR ]; then
	mkdir $DIR
fi

# Enter the directory to begin clone. Thanks to 'set -e' magic, this should give
# a useful message if DIR is not a directory.
cd $DIR

git init -q
git remote add -f $REMOTENAME $BRANCHES $REPO
git checkout $CHECKOUT