git-corb

#!/bin/bash
#
# git Check Out Remote Branch
# Track a branch and check it out with as little typing as possible
#

function usage() {
    echo "Usage: git corb [-f | --fetch] [<remote>] <branch>"
    echo
    echo "Check Out Remote Branch"
    echo
    echo "If you want to create a local branch that tracks a remote branch,"
    echo "while using the same name, you can use this command instead of"
    echo "typing the name several times in lengthy, error-prone command(s)."
    echo "Lots of special cases are detected and handled."
    echo
    echo "Args:"
    echo "    -f         - Fetch from the remote before creating a branch"
    echo "    <remote>   - A remote repository, defaults to 'origin'"
    echo "    <branch>   - The name of a remote branch"
}

GETOPT=$(getopt -u -o hf --long fetch -- "$@")
if [[ $? != 0 ]]; then
    usage
    exit 1
fi
set -- $GETOPT

while [[ 0 != $# ]]; do
    case "$1" in
        -f|--fetch)
            fetch=yes
            ;;
        -h)
            usage
            exit 0
            ;;
        --)
            shift
            break
            ;;
        *)
            echo "Unrecognized option ($1)??" >&2
            usage
            exit 1
            ;;
    esac
    shift
done

if [[ $# = 0 ]]; then
    usage
    exit 1
fi

remote=$1;
branch=$2;

# If no remote was specified, assume origin
if [[ -z $branch ]]; then
    branch=$remote
    remote="origin"
fi

# If a remote is actually given as part of the branch, split them and use it
if [[ -n $(echo $branch | awk '$1 ~ /\// { print }') ]]; then
    remote="${branch%%/*}"
    branch="${branch##*/}"
fi

# Fetch the branch from the remote, if requested
if [[ -n $fetch ]]; then
    echo "] git fetch $remote $branch"
    git fetch "$remote" "$branch"
fi

track_remote=$(git config "branch.$branch.remote")
track_branch=$(git config "branch.$branch.merge")
track_branch="${track_branch##*/}"
if [[ $remote = $track_remote && $branch = $track_branch ]]; then
    echo "$branch already tracks $remote/$branch."
    echo "] git checkout $branch"
    git checkout "$branch"
elif [[ -n $track_remote ]]; then
    echo "$branch tracks $track_remote/$track_branch, not $remote/$branch!"
    exit 1
elif [[ -z $(git for-each-ref "refs/remotes/$remote/$branch") ]]; then
    echo "There is no $remote/$branch (tracking) branch!"
    exit 1
elif [[ -z $(git for-each-ref "refs/heads/$branch") ]]; then
    echo "Attempting to checkout and have $branch track from $remote:"
    echo "] git checkout -b $branch $remote/$branch"
    git checkout -b "$branch" "$remote/$branch"
elif git rev-list "$remote/$branch..$branch" | grep -q .; then
    echo "Making $branch track $remote/$branch would lose information!"
    exit 1
else
    echo "Replacing $branch to track $remote/$branch:"
    echo "] git checkout $remote/$branch # Make sure we don't have $branch checked out"
    git checkout "$remote/$branch" || exit $?
    echo "] git branch -D $branch # Delete non-tracking local branch"
    git branch -D "$branch" || exit $?
    echo "] git checkout -b $branch $remote/$branch"
    git checkout -b "$branch" "$remote/$branch"
fi
exit $?