Return 0 if dropbox is running.

is_dropbox_running.sh

is_dropbox_running() {
  # Return 0 if dropbox is running.
  # Thanks to Official Dropbox Command Line Interface.
  # https://www.dropboxwiki.com/tips-and-tricks/using-the-official-dropbox-command-line-interface-cli
  if [[ -r ~/.dropbox/dropbox.pid ]]; then
    pid=$(cat ~/.dropbox/dropbox.pid)
  else
    return 1
  fi
  if [[ "$OSTYPE" == "linux-gnu" ]]; then
    # Linux
    if [[ -f /proc/${pid}/cmdline ]]; then
      grep -qi dropbox /proc/${pid}/cmdline
      return $?
    else
      return 1
    fi
  elif [[ "$OSTYPE" == "darwin"* ]]; then
    # macOS
    ps -p $pid -o command | grep -qi dropbox.app
    return $?
  else
    # Unknown.
    return 1
  fi
}