git-init-empty

#!/usr/bin/env bash
#
# git-init-empty - create a fresh Git repository and start it with a single
#                  empty "init" commit authored by "nobody <nobody@nowhere>".
#
# Usage:
#   git-init-empty [DIRECTORY] [-q|--quiet] [-h|--help]
#
# If DIRECTORY is omitted the current directory is used. When provided the
# directory will be created if it does not yet exist. After initialising the
# repository the script adds an empty commit with the message "init" so that
# a new branch has a first baseline revision straight away.
#
# The commit is made with the author/committer set to:
#   name : nobody
#   email: nobody@nowhere
#
# Exit codes:
#   0  success
#   1  invalid usage
#   2  directory already contains Git repository with history
#   3  git is not available
#
# Examples:
#   git-init-empty              # initialise the current directory
#   git-init-empty my/project   # create directory and initialise it
#   git-init-empty -q new/repo  # same as above but run quietly
#
# This script is intentionally minimal so it can be copied around quickly
# but it still follows good shell-scripting practices: strict error handling,
# helpful messages, and POSIX-compatible option parsing.
#

set -euo pipefail

print_help() {
  grep -E '^#( |$)' "$0" | sed -E 's/^# ?//'
}

quiet=false
target_dir=""

while [[ $# -gt 0 ]]; do
  case "$1" in
    -h|--help)
      print_help
      exit 0
      ;;
    -q|--quiet)
      quiet=true
      shift
      ;;
    -*)
      echo "Unknown option: $1" >&2
      print_help
      exit 1
      ;;
    *)
      if [[ -z "$target_dir" ]]; then
        target_dir="$1"
        shift
      else
        echo "ERROR: Only one positional DIRECTORY argument allowed." >&2
        exit 1
      fi
      ;;
  esac
done

# default to current directory
if [[ -z "$target_dir" ]]; then
  target_dir="."
fi

# ensure directory exists (unless it's ".")
if [[ "$target_dir" != "." ]]; then
  mkdir -p -- "$target_dir"
fi

cd -- "$target_dir"

if ! command -v git >/dev/null 2>&1; then
  echo "ERROR: git command not found." >&2
  exit 3
fi

if [[ -d .git ]]; then
  # Already a Git repository – allow proceeding only when it has no commits yet.
  if git rev-parse --quiet --verify HEAD >/dev/null; then
    echo "ERROR: Directory '$PWD' is already a Git repository with history." >&2
    exit 2
  else
    [[ $quiet == true ]] || echo "Existing empty repository detected."
  fi
else
  git init ${quiet:+-q}
fi

GIT_AUTHOR_NAME="nobody" \
GIT_AUTHOR_EMAIL="nobody@nowhere" \
GIT_COMMITTER_NAME="nobody" \
GIT_COMMITTER_EMAIL="nobody@nowhere" \
git commit --allow-empty -m "init" ${quiet:+-q}

$quiet || echo "Repository initialised at '$PWD'"