Which

A PHP library for locating commands in a PATH.

Requirements

This library requires PHP 5.6, or newer.

Installation

This package uses composer so you can just add nubs/which as a dependency to your composer.json file or execute the following command:

composer require nubs/which

Example

Here is a quick example to demonstrate how this library is generally meant to be used:

$locatorFactory = new \Nubs\Which\LocatorFactory\PlatformLocatorFactory();
$locator = $locatorFactory->create();

echo $locator->locate('php');
// /usr/bin/php

Usage

Constructing a Locator

There are several ways to create a locator. The preferred way is to use the brianium/habitat constructor. Habitat makes accessing the environment variables easy, even in cases where the $_ENV superglobal isn't populated. You can use it like this:

$habitat = new \Habitat\Habitat();
$environment = $habitat->getEnvironment();
$locatorFactory = new \Nubs\Which\LocatorFactory\PlatformLocatorFactory();
$locator = $locatorFactory->create($environment);

Habitat environment is not necessary. Without passing an environment, PHP's built-in getenv will be used:

$locatorFactory = new \Nubs\Which\LocatorFactory\PlatformLocatorFactory();
$locator = $locatorFactory->create();

There are also two platform-specific factories in case you don't want to rely on the platform detection in the PlatformLocatorFactory. If you are on a POSIXy system (e.g., Linux, OSX, BSD), you can use the PosixLocatorFactory and if you are on a Windows system you can use the WindowsLocatorFactory.

$locatorFactory = new \Nubs\Which\LocatorFactory\PosixLocatorFactory();
$locator = $locatorFactory->create();

// or

$locatorFactory = new \Nubs\Which\LocatorFactory\WindowsLocatorFactory();
$locator = $locatorFactory->create();

Finally, if you want full control over the paths that are searched, you can use specify exactly which paths to use:

$paths = ['/opt/special/bin', '/usr/local/bin', '/usr/bin', '/bin'];
$pathBuilder = new \Nubs\Which\PathBuilder\PosixPathBuilder($paths);
$locator = new \Nubs\Which\Locator($pathBuilder);

// or

$paths = ['C:\\Windows\\System32', 'C:\\Windows'];
$pathExtensions = ['.exe', '.com'];
$pathBuilder = new \Nubs\Which\PathBuilder\WindowsPathBuilder(
    $paths,
    $pathExtensions
);
$locator = new \Nubs\Which\Locator($pathBuilder);

Locating commands

The locator can find commands based off of its configured paths and will return null if the command could not be found:

$locatorFactory = new \Nubs\Which\LocatorFactory\PlatformLocatorFactory();
$locator = $locatorFactory->create();

echo $locator->locate('php');
// /usr/bin/php

var_dump($locator->locate('asdf'));
// NULL

It can also be given an absolute or a relative path, in which case the configured paths are ignored and pathing is done based off the current directory:

$locatorFactory = new \Nubs\Which\LocatorFactory\PlatformLocatorFactory();
$locator = $locatorFactory->create();

echo $locator->locate('/opt/php/bin/php');
// /opt/php/bin/php

chdir('/opt/php');

echo $locator->locate('bin/php');
// /opt/php/bin/php

Finally, an additional locateAll method is included. If a command exists at multiple places on the PATH, this will return all of them. It operates under all the rules as the standard locate method.

$locatorFactory = new \Nubs\Which\LocatorFactory\PlatformLocatorFactory();
$locator = $locatorFactory->create();

var_dump($locator->locateAll('php'));
// array(2) {
//   [0] =>
//   string(12) "/usr/bin/php"
//   [1] =>
//   string(16) "/opt/php/bin/php"
// }

var_dump($locator->locate('asdf'));
// array(0) {
// }

var_dump($locator->locateAll('/opt/php/bin/php'));
// array(1) {
//   [0] =>
//   string(16) "/opt/php/bin/php"
// }

chdir('/opt/php');

var_dump($locator->locateAll('bin/php'));
// array(1) {
//   [0] =>
//   string(16) "/opt/php/bin/php"
// }

CLI Interface

There is also a CLI interface for both POSIX systems and Windows that imitates the standard which command. It is available as nubs/which-cli.

Why?

I created which in order to fill a hole I came across: Detecting whether a user has a certain command installed. Primarily this was for sensible, a library that picks the user's preferred editor/browser/pager and falls back to a sensible default if no preference is specified. which provides the ability for sensible to decide whether the different command choices exist. Read more about it on my blog.

Similar Projects

I am also aware of a node.js library with a similar role: node-which.

License

which is licensed under the MIT license. See LICENSE for the full license text.