git pr command

git-pr

#!/bin/sh
#/ Usage: git pr [<branch>]
#/ Open the pull request page for <branch>, or the current branch if not
#/ specified. Lands on the new pull request page when no PR exists yet.
#/ The branch must already be pushed

# Based on script from @rtomayko
set -e

# usage message
if [ "$1" == "--help" -o "$1" == '-h' ]; then
    grep ^#/ "$0" | cut -c4-
    exit
fi

remote_url=$(git config --get remote.origin.url)
giturl=$(echo $remote_url | perl -pe's/(git@|https:\/\/)?github.com(:|\/)(\w+)\/((-|\w)+)(.git$)?/$3\/$4/')
repo_with_owner=$(echo $giturl | ruby -pe 'gsub(/\.git$/, "")')

# figure out the branch
branch=${1:-"$(git symbolic-ref HEAD | sed 's@refs/heads/@@')"}

# check that the branch exists in the origin remote first
if git rev-parse "refs/remotes/origin/$branch" 1>/dev/null 2>&1; then
    exec open "https://github.com/$repo_with_owner/pull/$branch"
else
    echo "error: branch '$branch' does not exist on the origin remote." 1>&2
    echo "       try again after pushing the branch"
fi