macOS custom quick actions (ie “New File”)

Set custom Automator params:
- Workflow receives current «files or folders» in «Finder»
- Add action: Run Shell Script
- Pass input: as arguments

for f in "$@"
do
  # If user right-clicked a file, use its parent folder
  if [ -f "$f" ]; then
    dir="$(dirname "$f")"
  else
    dir="$f"
  fi

  # Create a new untitled file safely
  newfile="$dir/NewFile.txt"
  n=1
  while [ -e "$newfile" ]; do
    newfile="$dir/NewFile $n.txt"
    ((n++))
  done

  touch "$newfile"
done