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Console Input (Arguments & Options)

4.2 version

Console Input (Arguments & Options)

The most interesting part of the commands are the arguments and options that you can make available. These arguments and options allow you to pass dynamic information from the terminal to the command.

Using Command Arguments

Arguments are the strings - separated by spaces - that come after the command name itself. They are ordered, and can be optional or required. For example, to add an optional last_name argument to the command and make the name argument required:

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// ...
use Symfony\Component\Console\Input\InputArgument;

class GreetCommand extends Command
{
    // ...

    protected function configure()
    {
        $this
            // ...
            ->addArgument('name', InputArgument::REQUIRED, 'Who do you want to greet?')
            ->addArgument('last_name', InputArgument::OPTIONAL, 'Your last name?')
        ;
    }
}

You now have access to a last_name argument in your command:

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// ...
class GreetCommand extends Command
{
    // ...

    protected function execute(InputInterface $input, OutputInterface $output)
    {
        $text = 'Hi '.$input->getArgument('name');

        $lastName = $input->getArgument('last_name');
        if ($lastName) {
            $text .= ' '.$lastName;
        }

        $output->writeln($text.'!');
    }
}

The command can now be used in either of the following ways:

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$ php bin/console app:greet Fabien
Hi Fabien!

$ php bin/console app:greet Fabien Potencier
Hi Fabien Potencier!

It is also possible to let an argument take a list of values (imagine you want to greet all your friends). Only the last argument can be a list:

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$this
    // ...
    ->addArgument(
        'names',
        InputArgument::IS_ARRAY,
        'Who do you want to greet (separate multiple names with a space)?'
    );

To use this, just specify as many names as you want:

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$ php bin/console app:greet Fabien Ryan Bernhard

You can access the names argument as an array:

$names = $input->getArgument('names');
if (count($names) > 0) {
    $text .= ' '.implode(', ', $names);
}

There are three argument variants you can use:

InputArgument::REQUIRED
The argument is mandatory. The command doesn't run if the argument isn't provided;
InputArgument::OPTIONAL
The argument is optional and therefore can be omitted. This is the default behavior of arguments;
InputArgument::IS_ARRAY
The argument can contain any number of values. For that reason, it must be used at the end of the argument list.

You can combine IS_ARRAY with REQUIRED and OPTIONAL like this:

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$this
    // ...
    ->addArgument(
        'names',
        InputArgument::IS_ARRAY | InputArgument::REQUIRED,
        'Who do you want to greet (separate multiple names with a space)?'
    );

Using Command Options

Unlike arguments, options are not ordered (meaning you can specify them in any order) and are specified with two dashes (e.g. --yell). Options are always optional, and can be setup to accept a value (e.g. --dir=src) or simply as a boolean flag without a value (e.g. --yell).

For example, add a new option to the command that can be used to specify how many times in a row the message should be printed:

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// ...
use Symfony\Component\Console\Input\InputOption;

$this
    // ...
    ->addOption(
        'iterations',
        null,
        InputOption::VALUE_REQUIRED,
        'How many times should the message be printed?',
        1
    );

Next, use this in the command to print the message multiple times:

for ($i = 0; $i < $input->getOption('iterations'); $i++) {
    $output->writeln($text);
}

Now, when you run the command, you can optionally specify a --iterations flag:

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# no --iterations provided, the default (1) is used
$ php bin/console app:greet Fabien
Hi Fabien!

$ php bin/console app:greet Fabien --iterations=5
Hi Fabien
Hi Fabien
Hi Fabien
Hi Fabien
Hi Fabien

# the order of options isn't important
$ php bin/console app:greet Fabien --iterations=5 --yell
$ php bin/console app:greet Fabien --yell --iterations=5
$ php bin/console app:greet --yell --iterations=5 Fabien

Tip

You can also declare a one-letter shortcut that you can call with a single dash, like -i:

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$this
    // ...
    ->addOption(
        'iterations',
        'i',
        InputOption::VALUE_REQUIRED,
        'How many times should the message be printed?',
        1
    );

Note that to comply with the docopt standard, long options can specify their values after a white space or an = sign (e.g. --iterations 5 or --iterations=5), but short options can only use white spaces or no separation at all (e.g. -i 5 or -i5).

Caution

While it is possible to separate an option from its value with a white space, using this form leads to an ambiguity should the option appear before the command name. For example, php app/console --iterations 5 app:greet Fabien is ambiguous; Symfony would interpret 5 as the command name. To avoid this situation, always place options after the command name, or avoid using a space to separate the option name from its value.

There are four option variants you can use:

InputOption::VALUE_IS_ARRAY
This option accepts multiple values (e.g. --dir=/foo --dir=/bar);
InputOption::VALUE_NONE
Do not accept input for this option (e.g. --yell). This is the default behavior of options;
InputOption::VALUE_REQUIRED
This value is required (e.g. --iterations=5 or -i5), the option itself is still optional;
InputOption::VALUE_OPTIONAL
This option may or may not have a value (e.g. --yell or --yell=loud).

You can combine VALUE_IS_ARRAY with VALUE_REQUIRED or VALUE_OPTIONAL like this:

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$this
    // ...
    ->addOption(
        'colors',
        null,
        InputOption::VALUE_REQUIRED | InputOption::VALUE_IS_ARRAY,
        'Which colors do you like?',
        array('blue', 'red')
    );

Options with optional arguments

There is nothing forbidding you to create a command with an option that optionally accepts a value, but it's a bit tricky. Consider this example:

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// ...
use Symfony\Component\Console\Input\InputOption;

$this
    // ...
    ->addOption(
        'yell',
        null,
        InputOption::VALUE_OPTIONAL,
        'Should I yell while greeting?'
    );

This option can be used in 3 ways: --yell, yell=louder, and not passing the option at all. However, it's hard to distinguish between passing the option without a value (greet --yell) and not passing the option (greet).

To solve this issue, you have to set the option's default value to false:

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// ...
use Symfony\Component\Console\Input\InputOption;

$this
    // ...
    ->addOption(
        'yell',
        null,
        InputOption::VALUE_OPTIONAL,
        'Should I yell while greeting?',
        false // this is the new default value, instead of null
    );

Now check the value of the option and keep in mind that false !== null:

$optionValue = $input->getOption('yell');
$yell = ($optionValue !== false);
$yellLouder = ($optionValue === 'louder');

Caution

Due to a PHP limitation, passing an empty string is indistinguishable from not passing any value at all. In command --prefix and command --prefix='' cases, the value of the prefix option will be null.

This work, including the code samples, is licensed under a Creative Commons BY-SA 3.0 license.