Bash - sync all git branches on remote fork from their parent repo

git-syncrepo

#!/usr/bin/env bash
#
# GitHub remote repo sync
#
# sync all local git branches on remote fork from their parent repo
#  - only works if in a local git repo that was cloned from a fork
#  - requires GitHub CLI (https://github.com/cli/cli/blob/trunk/docs/install_linux.md)

GITHUB_USERNAME="cgoldberg"

die() { echo "$*" 1>&2 ; exit 1; }

if ! git rev-parse --is-inside-work-tree >/dev/null 2>&1; then
    die "not in a git repo"
fi

repo=$(basename $(basename $(git remote get-url origin)) ".git")
default_branch=$(git remote show origin | sed -n '/HEAD branch/s/.*: //p')
echo
echo "syncing '${default_branch}' branch on remote fork from its parent"
gh repo sync "${GITHUB_USERNAME}/${repo}" --branch "${default_branch}" || die
echo
branches=($(git branch --format='%(upstream:short)' | grep origin | awk -F '/' '{print $NF}'))
branches_without_default=(${branches[@]/${default_branch}})
for branch in "${branches_without_default[@]}"; do
    echo "syncing '${branch}' branch on remote fork from its parent"
    gh repo sync "${GITHUB_USERNAME}/${repo}" --branch "${branch}"
    echo
done