Nette Command-Line

A lightweight library for building command-line applications in PHP. It provides:

• Argument parsing with switches, options, and positional arguments
• Colorful terminal output with ANSI support

Install it using Composer:

composer require nette/command-line

It requires PHP version 8.2 and supports PHP up to 8.5.

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Parsing Command-Line Arguments

Every CLI script needs to handle arguments like --verbose, -o output.txt, or plain file names. The Parser class offers the fastest way to get started: just write your help text and let the parser extract option definitions from it:

use Nette\CommandLine\Parser;

$parser = new Parser;
$parser->addFromHelp('
	-h, --help              Show this help
	-v, --verbose           Enable verbose mode
	-o, --output <file>     Output file
	-f, --format [type]     Output format (default: json)
	-I, --include <path>... Include paths
	--dry-run               Show what would be done
');

$args = $parser->parse();

That's it. The parser understands that --verbose is a switch, --output requires a value, --format has an optional value with json as fallback. Your help text stays in sync with actual option definitions.

The parse() method returns an associative array. Keys match option names exactly as defined, including the dashes:

[
	'--help' => true,         // or null if not used
	'--verbose' => null,
	'--output' => 'file.txt', // or null if not used
	'--format' => 'json',     // fallback from (default: json)
	'--include' => ['src', 'lib'],
	'--dry-run' => null,
]

By default, parse() reads from $_SERVER['argv']. You can pass a custom array for testing:

$args = $parser->parse(['--verbose', '-o', 'out.txt']);

Help Text Syntax

The parser extracts option definitions from formatted help text:

Syntax	Meaning
--verbose	Switch (no value)
-v, --verbose	Switch with short alias
--output <file>	Option with required value
--format [type]	Option with optional value
(default: json)	Sets fallback value
<path>...	Repeatable option

Each line defines one option. Option names must be separated from descriptions by at least two spaces.

Additional Configuration

Some settings can't be expressed in help text. Pass an array as the second parameter, keyed by option name:

$parser->addFromHelp('
	-c, --config <file>   Configuration file
	-I, --include <path>  Include path
	-n, --count <num>     Number of iterations
', [
	'--config' => [
		Parser::RealPath => true,
	],
	'--include' => [
		Parser::Repeatable => true,
	],
	'--count' => [
		Parser::Normalizer => fn($v) => (int) $v,
	],
]);

Available keys:

Key	Description
Parser::Repeatable	Collect multiple values into array
Parser::RealPath	Validate file exists and resolve to absolute path
Parser::Normalizer	Transform function fn($value) => ...
Parser::Default	Fallback value (same as (default: x) in help text)
Parser::Enum	Array of allowed values

Fluent API

When you need more control over option definitions, use the fluent API with addSwitch(), addOption(), and addArgument() methods. This approach gives you access to all features including normalizers, enums, and precise control over each parameter:

use Nette\CommandLine\Parser;

$parser = new Parser;
$parser
	->addSwitch('--verbose', '-v')
	->addOption('--output', '-o')
	->addArgument('file');

$args = $parser->parse();

By default, parse() reads from $_SERVER['argv']. You can pass a custom array for testing:

$args = $parser->parse(['--verbose', '-o', 'out.txt', 'input.txt']);

Switches, Options, and Arguments

There are three types of command-line inputs:

Switches are flags without values, like --verbose or -v. They parse as true when present, null when absent:

$parser->addSwitch('--verbose', '-v');
// --verbose  → true
// -v         → true
// (not used) → null

Options accept values, like --output file.txt. The value can be separated by space or =:

$parser->addOption('--output', '-o');
// --output file.txt    → 'file.txt'
// --output=file.txt    → 'file.txt'
// -o file.txt          → 'file.txt'
// --output             → throws exception (value required)
// (not used)           → null

Note that the option itself is always optional - not using it returns null. However, when used, the value is required by default. Set optionalValue: true to allow the option without a value (parses as true):

$parser->addOption('--format', '-f', optionalValue: true);
// --format json        → 'json'
// --format             → true
// (not used)           → null

When the same option is used multiple times without repeatable: true, the last value wins:

$parser->addOption('--output', '-o');
// -o first.txt -o second.txt  → 'second.txt'

Arguments are positional values without dashes. By default they are required. Set optional: true to make them optional:

$parser->addArgument('input');
// script.php file.txt  → 'file.txt'
// (not used)           → throws exception

$parser->addArgument('output', optional: true);
// (not used)           → null

$parser->addArgument('output', optional: true, fallback: 'out.txt');
// (not used)           → 'out.txt'

Use fallback to specify the value when an option or argument is not provided. For options with optionalValue: true, note that using the option without a value still parses as true, while the fallback is used only when the option is not present at all:

$parser->addOption('--format', '-f', optionalValue: true, fallback: 'json');
// --format xml  → 'xml'
// --format      → true (option used without value)
// (not used)    → 'json' (fallback)

Arguments can appear anywhere on the command line - they don't have to come after options:

// all of these are equivalent:
// script.php --verbose input.txt
// script.php input.txt --verbose

Restricting Values with Enum

Limit accepted values to a specific set:

$parser->addOption('--format', '-f', enum: ['json', 'xml', 'csv']);
// --format yaml  → throws "Value of option --format must be json, or xml, or csv."

Repeatable Options

Set repeatable: true to collect multiple values into an array:

$parser->addOption('--include', '-I', repeatable: true);
// -I src -I lib  → ['src', 'lib']
// (not used)     → []

$parser->addArgument('files', optional: true, repeatable: true);
// a.txt b.txt    → ['a.txt', 'b.txt']

Transforming Values

Use normalizer to transform parsed values:

$parser->addOption('--count', normalizer: fn($v) => (int) $v);
// --count 42  → 42 (integer)

For file path validation, use the built-in normalizeRealPath:

$parser->addOption('--config', normalizer: Parser::normalizeRealPath(...));
// --config app.ini     → '/full/path/to/app.ini'
// --config missing.ini → throws "File path 'missing.ini' not found."

Mixing Both Approaches

You can combine addFromHelp() with fluent methods when you need normalizers for some options:

$parser
	->addFromHelp('
		-v, --verbose  Enable verbose mode
		-q, --quiet    Suppress output
	')
	->addOption('--config', '-c', normalizer: Parser::normalizeRealPath(...),
		description: 'Configuration file')
	->addArgument('input', description: 'Input file');

Error Handling

The parser throws \Exception for invalid input:

use Nette\CommandLine\Parser;

$parser = new Parser;
$parser
	->addOption('--output', '-o')
	->addArgument('file');

try {
	$args = $parser->parse();
} catch (\Exception $e) {
	fwrite(STDERR, "Error: {$e->getMessage()}\n");
	exit(1);
}

Common error messages:

Error	Cause
Option --output requires argument.	Option used without required value
Unknown option --foo.	Unrecognized option
Missing required argument <file>.	Required argument not provided
Unexpected parameter foo.	Extra positional argument
Value of option --format must be json, or xml.	Value not in enum

Use isEmpty() to check if no command-line arguments were provided (i.e., user ran just script.php with nothing after it):

if ($parser->isEmpty()) {
	$parser->help();
	exit;
}

Handling --help and --version

When your script has required arguments, running script.php --help would normally fail because the required argument is missing. Use parseOnly() to check for info options first:

$parser = new Parser;
$parser
	->addSwitch('--help', '-h')
	->addSwitch('--version', '-V')
	->addArgument('input');  // required

// First, check info options (no validation, no exceptions)
$info = $parser->parseOnly(['--help', '--version']);

if ($info['--help']) {
	$parser->help();
	exit;
}

if ($info['--version']) {
	echo "1.0.0\n";
	exit;
}

// Now do full parsing with validation
$args = $parser->parse();

The parseOnly() method:

• Parses only the specified options, ignoring everything else
• Respects aliases (-h → --help)
• Never throws exceptions
• Returns null for options that weren't used

Complete Example

Here's a real-world file converter script combining Parser and Console:

#!/usr/bin/env php
<?php
use Nette\CommandLine\Parser;

require __DIR__ . '/vendor/autoload.php';

$parser = new Parser;
$parser
	->addFromHelp('
		-h, --help           Show this help
		-v, --verbose        Show detailed output
		-n, --dry-run        Show what would be done
		-f, --format [type]  Output format (default: json)
		-o, --output <file>  Output file
	', [
		'--format' => [
			Parser::Enum => ['json', 'xml', 'csv'],
		],
	])
	->addArgument('input', normalizer: Parser::normalizeRealPath(...));

// Handle --help before validation (avoids "missing argument" error)
if ($parser->isEmpty() || $parser->parseOnly(['--help'])['--help']) {
	echo "Usage: convert [options] <input>\n\n";
	$parser->help();
	exit;
}

try {
	$args = $parser->parse();
} catch (\Exception $e) {
	fwrite(STDERR, "Error: {$e->getMessage()}\n");
	exit(1);
}

if ($args['--verbose']) {
	echo "Converting {$args['input']} to {$args['--format']}...\n";
}

if ($args['--dry-run']) {
	echo "Dry run: No changes made.\n";
	exit;
}

// ... conversion logic here ...

echo "Done!\n";

The script accepts commands like:

• convert input.txt - convert with defaults
• convert -v --format xml input.txt - verbose, XML format
• convert -o result.txt input.txt - specify output file
• convert --help - show help (works even without input file)