Laravel - Artisan Console - Arguments

All user supplied arguments and options are wrapped in curly braces. In the following example, the command defines one required argument: user:

     * The name and signature of the console command.
     * @var string
    protected $signature = 'mail:send {user}';

You may also make arguments optional or define default values for arguments:

    // Optional argument...
    mail:send {user?}
    // Optional argument with default value...
    mail:send {user=foo}