Checkout PR, using GitHub API to determine what to track

checkout_pr.sh

#!/bin/sh
set -o errexit
[ $# != 1 ] && { >&2 echo 'Argument: <pull request id>'; exit 1; }

# Get origin remote
origin=$(git remote get-url origin)

# Find target ("owner/repo") of PR
temp=${origin#*github.com?}
[ $origin = $temp ] && { >&2 echo Unrecognized origin.; exit 1; }
target=${temp%.git}

# Find source ("owner/repo") of PR and remote name and branch name
temp=$(curl --silent https://github.com/$target/pull/$1 | grep --max-count=1 head-ref | cut --delimiter=\" --fields=2)
source=${temp%%:*}
remote=$(echo $origin | sed "s $target $source ")
branch=${temp#*:}

# Set up branch and checkout
git fetch --no-tags $remote $branch:pr/$1
git config branch.pr/$1.remote $remote
git config branch.pr/$1.merge refs/heads/$branch
git checkout pr/$1

I needed to make the following change to make this work on MacOS:

-temp=$(curl --silent https://github.com/$target/pull/$1 | grep --max-count=1 head-ref | cut --delimiter=\" --fields=2)
+temp=$(curl --silent https://github.com/$target/pull/$1 | grep --max-count=1 head-ref | cut -d\" -f2)

ChatGPT promises me that this should work cross-platform.

Interesting. I've gotten into a habit of using long GNU-style command line options in all my scripts because it's generally a little more clear about what it's actually doing. I did know there were some situations/environments that only support short/POSIX-style switches, and apparently we've run into one here. If I'm going to publish this as a standalone thing, it might make sense to switch everything over to POSIX switches. I'm not sure.