Script to clone or init a repository in a git-worktree setup

gitwt.sh

#!/bin/zsh

# Usage:
#   gitwt <git-uri>              Clone an existing repo into a worktree setup
#   gitwt -c <project-name>      Create a new project from scratch with worktree setup
#
# Examples:
#   gitwt git@github.com:commercetools/the-repo-i-want-to-clone.git
#   gitwt -c my-new-project

set -euo pipefail

function usage() {
  echo "Usage:"
  echo "  gitwt <git-uri>            Clone a repo into a worktree setup"
  echo "  gitwt -c <project-name>    Create a new project with worktree setup"
  echo ""
  echo "Examples:"
  echo "  gitwt git@github.com:org/repo.git"
  echo "  gitwt -c my-new-project"
}

function check_dir() {
  local name="$1"
  if [[ -d "$name" ]]; then
    echo "Error: directory '$name' already exists"
    exit 1
  fi
}

function link_bare() {
  echo "gitdir: ./.bare" > .git
  git config remote.origin.fetch "+refs/heads/*:refs/remotes/origin/*"
}

function create_project() {
  local project_name="$1"
  local default_branch="main"
  local worktree_dir="${project_name}_${default_branch}"

  check_dir "$project_name"

  echo "Creating new worktree project '$project_name'..."

  mkdir "$project_name"
  cd "$project_name"

  git init --bare .bare

  link_bare

  git worktree add "$worktree_dir" -b "$default_branch"

  echo ""
  echo "Done! Your worktree project is ready:"
  echo "  $project_name/"
  echo "    .bare/            (git database)"
  echo "    .git              (pointer to .bare)"
  echo "    $worktree_dir/    (worktree on $default_branch branch)"
  echo ""
  echo "Next steps:"
  echo "  cd $project_name/$worktree_dir"
  echo "  have fun!"
}

function clone_repo() {
  local uri="$1"

  # Extract repo name from URI
  # Handles both SSH (git@github.com:org/repo.git) and HTTPS (https://github.com/org/repo.git)
  local repo_name="${uri:t:r}"

  if [[ -z "$repo_name" ]]; then
    echo "Error: could not extract repository name from '$uri'"
    exit 1
  fi

  check_dir "$repo_name"

  echo "Setting up bare worktree repo for '$repo_name'..."

  mkdir "$repo_name"
  cd "$repo_name"

  git clone --bare "$uri" .bare

  link_bare

  local default_branch=$(git -C .bare symbolic-ref --short HEAD)
  local worktree_dir="${repo_name}_${default_branch}"

  git worktree add "$worktree_dir" "$default_branch"
  git branch --set-upstream-to="origin/$default_branch" "$default_branch"

  echo ""
  echo "Done! Your worktree repo is ready:"
  echo "  $repo_name/"
  echo "    .bare/            (git database)"
  echo "    .git              (pointer to .bare)"
  echo "    $worktree_dir/    (worktree on $default_branch branch)"
  echo ""
  echo "Next steps:"
  echo "  cd $repo_name/$worktree_dir"
  echo "  have fun!"
}

# --- Main ---

if [[ $# -eq 2 && "$1" == "-c" ]]; then
  create_project "$2"
elif [[ $# -eq 1 && "$1" != "-c" ]]; then
  clone_repo "$1"
else
  usage
  exit 1
fi