Processes

Introduction
Invoking Processes
Asynchronous Processes
- Process IDs and Signals
- Asynchronous Process Output
Concurrent Processes
- Naming Pool Processes
- Pool Process IDs and Signals
Testing

Introduction

Laravel provides an expressive, minimal API around the Symfony Process component, allowing you to conveniently invoke external processes from your Laravel application. Laravel's process features are focused on the most common use cases and a wonderful developer experience.

Invoking Processes

To invoke a process, you may use the run and start methods offered by the Process facade. The run method will invoke a process and wait for the process to finish executing, while the start method is used for asynchronous process execution. We'll examine both approaches within this documentation. First, let's examine how to invoke a basic, synchronous process and inspect its result:

use Illuminate\Support\Facades\Process;
 
$result = Process::run('ls -la');
 
return $result->output();

Of course, the Illuminate\Contracts\Process\ProcessResult instance returned by the run method offers a variety of helpful methods that may be used to inspect the process result:

$result = Process::run('ls -la');
 
$result->successful();
$result->failed();
$result->exitCode();
$result->output();
$result->errorOutput();

Throwing Exceptions

If you have a process result and would like to throw an instance of Illuminate\Process\Exceptions\ProcessFailedException if the exit code is greater than zero (thus indicating failure), you may use the throw and throwIf methods. If the process did not fail, the process result instance will be returned:

$result = Process::run('ls -la')->throw();
 
$result = Process::run('ls -la')->throwIf($condition);

Process Options

Of course, you may need to customize the behavior of a process before invoking it. Thankfully, Laravel allows you to tweak a variety of process features, such as the working directory, timeout, and environment variables.

Working Directory Path

You may use the path method to specify the working directory of the process. If this method is not invoked, the process will inherit the working directory of the currently executing PHP script:

$result = Process::path(__DIR__)->run('ls -la');

Input

You may provide input via the "standard input" of the process using the input method:

$result = Process::input('Hello World')->run('cat');

Timeouts

By default, processes will throw an instance of Illuminate\Process\Exceptions\ProcessTimedOutException after executing for more than 60 seconds. However, you can customize this behavior via the timeout method:

$result = Process::timeout(120)->run('bash import.sh');

Or, if you would like to disable the process timeout entirely, you may invoke the forever method:

$result = Process::forever()->run('bash import.sh');

The idleTimeout method may be used to specify the maximum number of seconds the process may run without returning any output:

$result = Process::timeout(60)->idleTimeout(30)->run('bash import.sh');

Environment Variables

Environment variables may be provided to the process via the env method. The invoked process will also inherit all of the environment variables defined by your system:

$result = Process::forever()
            ->env(['IMPORT_PATH' => __DIR__])
            ->run('bash import.sh');

If you wish to remove an inherited environment variable from the invoked process, you may provide that environment variable with a value of false:

$result = Process::forever()
            ->env(['LOAD_PATH' => false])
            ->run('bash import.sh');

TTY Mode

The tty method may be used to enable TTY mode for your process. TTY mode connects the input and output of the process to the input and output of your program, allowing your process to open an editor like Vim or Nano as a process:

Process::forever()->tty()->run('vim');

Process Output

As previously discussed, process output may be accessed using the output (stdout) and errorOutput (stderr) methods on a process result:

use Illuminate\Support\Facades\Process;
 
$result = Process::run('ls -la');
 
echo $result->output();
echo $result->errorOutput();

However, output may also be gathered in real-time by passing a closure as the second argument to the run method. The closure will receive two arguments: the "type" of output (stdout or stderr) and the output string itself:

$result = Process::run('ls -la', function (string $type, string $output) {
    echo $output;
});

Laravel also offers the seeInOutput and seeInErrorOutput methods, which provide a convenient way to determine if a given string was contained in the process' output:

if (Process::run('ls -la')->seeInOutput('laravel')) {
    // ...
}

Disabling Process Output

If your process is writing a significant amount of output that you are not interested in, you can conserve memory by disabling output retrieval entirely. To accomplish this, invoke the quietly method while building the process:

use Illuminate\Support\Facades\Process;
 
$result = Process::quietly()->run('bash import.sh');

Pipelines

Sometimes you may want to make the output of one process the input of another process. This is often referred to as "piping" the output of a process into another. The pipe method provided by the Process facades makes this easy to accomplish. The pipe method will execute the piped processes synchronously and return the process result for the last process in the pipeline:

use Illuminate\Process\Pipe;
use Illuminate\Support\Facades\Process;
 
$result = Process::pipe(function (Pipe $pipe) {
    $pipe->command('cat example.txt');
    $pipe->command('grep -i "laravel"');
});
 
if ($result->successful()) {
    // ...
}

If you do not need to customize the individual processes that make up the pipeline, you may simply pass an array of command strings to the pipe method:

$result = Process::pipe([
    'cat example.txt',
    'grep -i "laravel"',
]);

The process output may be gathered in real-time by passing a closure as the second argument to the pipe method. The closure will receive two arguments: the "type" of output (stdout or stderr) and the output string itself:

$result = Process::pipe(function (Pipe $pipe) {
    $pipe->command('cat example.txt');
    $pipe->command('grep -i "laravel"');
}, function (string $type, string $output) {
    echo $output;
});

Laravel also allows you to assign string keys to each process within a pipeline via the as method. This key will also be passed to the output closure provided to the pipe method, allowing you to determine which process the output belongs to:

$result = Process::pipe(function (Pipe $pipe) {
    $pipe->as('first')->command('cat example.txt');
    $pipe->as('second')->command('grep -i "laravel"');
})->start(function (string $type, string $output, string $key) {
    // ...
});

Asynchronous Processes

While the run method invokes processes synchronously, the start method may be used to invoke a process asynchronously. This allows your application to continue performing other tasks while the process runs in the background. Once the process has been invoked, you may utilize the running method to determine if the process is still running:

$process = Process::timeout(120)->start('bash import.sh');
 
while ($process->running()) {
    // ...
}
 
$result = $process->wait();

As you may have noticed, you may invoke the wait method to wait until the process is finished executing and retrieve the process result instance:

$process = Process::timeout(120)->start('bash import.sh');
 
// ...
 
$result = $process->wait();

Process IDs and Signals

The id method may be used to retrieve the operating system assigned process ID of the running process:

$process = Process::start('bash import.sh');
 
return $process->id();

You may use the signal method to send a "signal" to the running process. A list of predefined signal constants can be found within the PHP documentation:

$process->signal(SIGUSR2);

Asynchronous Process Output

While an asynchronous process is running, you may access its entire current output using the output and errorOutput methods; however, you may utilize the latestOutput and latestErrorOutput to access the output from the process that has occurred since the output was last retrieved:

$process = Process::timeout(120)->start('bash import.sh');
 
while ($process->running()) {
    echo $process->latestOutput();
    echo $process->latestErrorOutput();
 
    sleep(1);
}

Like the run method, output may also be gathered in real-time from asynchronous processes by passing a closure as the second argument to the start method. The closure will receive two arguments: the "type" of output (stdout or stderr) and the output string itself:

$process = Process::start('bash import.sh', function (string $type, string $output) {
    echo $output;
});
 
$result = $process->wait();

Concurrent Processes

Laravel also makes it a breeze to manage a pool of concurrent, asynchronous processes, allowing you to easily execute many tasks simultaneously. To get started, invoke the pool method, which accepts a closure that receives an instance of Illuminate\Process\Pool.

Within this closure, you may define the processes that belong to the pool. Once a process pool is started via the start method, you may access the collection of running processes via the running method:

use Illuminate\Process\Pool;
use Illuminate\Support\Facades\Process;
 
$pool = Process::pool(function (Pool $pool) {
    $pool->path(__DIR__)->command('bash import-1.sh');
    $pool->path(__DIR__)->command('bash import-2.sh');
    $pool->path(__DIR__)->command('bash import-3.sh');
})->start(function (string $type, string $output, int $key) {
    // ...
});
 
while ($pool->running()->isNotEmpty()) {
    // ...
}
 
$results = $pool->wait();

As you can see, you may wait for all of the pool processes to finish executing and resolve their results via the wait method. The wait method returns an array accessible object that allows you to access the process result instance of each process in the pool by its key:

$results = $pool->wait();
 
echo $results[0]->output();

Or, for convenience, the concurrently method may be used to start an asynchronous process pool and immediately wait on its results. This can provide particularly expressive syntax when combined with PHP's array destructuring capabilities:

[$first, $second, $third] = Process::concurrently(function (Pool $pool) {
    $pool->path(__DIR__)->command('ls -la');
    $pool->path(app_path())->command('ls -la');
    $pool->path(storage_path())->command('ls -la');
});
 
echo $first->output();

Naming Pool Processes

Accessing process pool results via a numeric key is not very expressive; therefore, Laravel allows you to assign string keys to each process within a pool via the as method. This key will also be passed to the closure provided to the start method, allowing you to determine which process the output belongs to:

$pool = Process::pool(function (Pool $pool) {
    $pool->as('first')->command('bash import-1.sh');
    $pool->as('second')->command('bash import-2.sh');
    $pool->as('third')->command('bash import-3.sh');
})->start(function (string $type, string $output, string $key) {
    // ...
});
 
$results = $pool->wait();
 
return $results['first']->output();

Pool Process IDs and Signals

Since the process pool's running method provides a collection of all invoked processes within the pool, you may easily access the underlying pool process IDs:

$processIds = $pool->running()->each->id();

And, for convenience, you may invoke the signal method on a process pool to send a signal to every process within the pool:

$pool->signal(SIGUSR2);

Testing

Many Laravel services provide functionality to help you easily and expressively write tests, and Laravel's process service is no exception. The Process facade's fake method allows you to instruct Laravel to return stubbed / dummy results when processes are invoked.

Faking Processes

To explore Laravel's ability to fake processes, let's imagine a route that invokes a process:

use Illuminate\Support\Facades\Process;
use Illuminate\Support\Facades\Route;
 
Route::get('/import', function () {
    Process::run('bash import.sh');
 
    return 'Import complete!';
});

When testing this route, we can instruct Laravel to return a fake, successful process result for every invoked process by calling the fake method on the Process facade with no arguments. In addition, we can even assert that a given process was "run":

<?php
 
namespace Tests\Feature;
 
use Illuminate\Process\PendingProcess;
use Illuminate\Contracts\Process\ProcessResult;
use Illuminate\Support\Facades\Process;
use Tests\TestCase;
 
class ExampleTest extends TestCase
{
    public function test_process_is_invoked(): void
    {
        Process::fake();
 
        $response = $this->get('/import');
 
        // Simple process assertion...
        Process::assertRan('bash import.sh');
 
        // Or, inspecting the process configuration...
        Process::assertRan(function (PendingProcess $process, ProcessResult $result) {
            return $process->command === 'bash import.sh' &&
                   $process->timeout === 60;
        });
    }
}

As discussed, invoking the fake method on the Process facade will instruct Laravel to always return a successful process result with no output. However, you may easily specify the output and exit code for faked processes using the Process facade's result method:

Process::fake([
    '*' => Process::result(
        output: 'Test output',
        errorOutput: 'Test error output',
        exitCode: 1,
    ),
]);

Faking Specific Processes

As you may have noticed in a previous example, the Process facade allows you to specify different fake results per process by passing an array to the fake method.

The array's keys should represent command patterns that you wish to fake and their associated results. The * character may be used as a wildcard character. Any process commands that have not been faked will actually be invoked. You may use the Process facade's result method to construct stub / fake results for these commands:

Process::fake([
    'cat *' => Process::result(
        output: 'Test "cat" output',
    ),
    'ls *' => Process::result(
        output: 'Test "ls" output',
    ),
]);

If you do not need to customize the exit code or error output of a faked process, you may find it more convenient to specify the fake process results as simple strings:

Process::fake([
    'cat *' => 'Test "cat" output',
    'ls *' => 'Test "ls" output',
]);

Faking Process Sequences

If the code you are testing invokes multiple processes with the same command, you may wish to assign a different fake process result to each process invocation. You may accomplish this via the Process facade's sequence method:

Process::fake([
    'ls *' => Process::sequence()
                ->push(Process::result('First invocation'))
                ->push(Process::result('Second invocation')),
]);

Faking Asynchronous Process Lifecycles

Thus far, we have primarily discussed faking processes which are invoked synchronously using the run method. However, if you are attempting to test code that interacts with asynchronous processes invoked via start, you may need a more sophisticated approach to describing your fake processes.

For example, let's imagine the following route which interacts with an asynchronous process:

use Illuminate\Support\Facades\Log;
use Illuminate\Support\Facades\Route;
 
Route::get('/import', function () {
    $process = Process::start('bash import.sh');
 
    while ($process->running()) {
        Log::info($process->latestOutput());
        Log::info($process->latestErrorOutput());
    }
 
    return 'Done';
});

To properly fake this process, we need to be able to describe how many times the running method should return true. In addition, we may want to specify multiple lines of output that should be returned in sequence. To accomplish this, we can use the Process facade's describe method:

Process::fake([
    'bash import.sh' => Process::describe()
            ->output('First line of standard output')
            ->errorOutput('First line of error output')
            ->output('Second line of standard output')
            ->exitCode(0)
            ->iterations(3),
]);

Let's dig into the example above. Using the output and errorOutput methods, we may specify multiple lines of output that will be returned in sequence. The exitCode method may be used to specify the final exit code of the fake process. Finally, the iterations method may be used to specify how many times the running method should return true.

Available Assertions

As previously discussed, Laravel provides several process assertions for your feature tests. We'll discuss each of these assertions below.

assertRan

Assert that a given process was invoked:

use Illuminate\Support\Facades\Process;
 
Process::assertRan('ls -la');

The assertRan method also accepts a closure, which will receive an instance of a process and a process result, allowing you to inspect the process' configured options. If this closure returns true, the assertion will "pass":

Process::assertRan(fn ($process, $result) =>
    $process->command === 'ls -la' &&
    $process->path === __DIR__ &&
    $process->timeout === 60
);

The $process passed to the assertRan closure is an instance of Illuminate\Process\PendingProcess, while the $result is an instance of Illuminate\Contracts\Process\ProcessResult.

assertDidntRun

Assert that a given process was not invoked:

use Illuminate\Support\Facades\Process;
 
Process::assertDidntRun('ls -la');

Like the assertRan method, the assertDidntRun method also accepts a closure, which will receive an instance of a process and a process result, allowing you to inspect the process' configured options. If this closure returns true, the assertion will "fail":

Process::assertDidntRun(fn (PendingProcess $process, ProcessResult $result) =>
    $process->command === 'ls -la'
);

assertRanTimes

Assert that a given process was invoked a given number of times:

use Illuminate\Support\Facades\Process;
 
Process::assertRanTimes('ls -la', times: 3);

The assertRanTimes method also accepts a closure, which will receive an instance of a process and a process result, allowing you to inspect the process' configured options. If this closure returns true and the process was invoked the specified number of times, the assertion will "pass":

Process::assertRanTimes(function (PendingProcess $process, ProcessResult $result) {
    return $process->command === 'ls -la';
}, times: 3);

Preventing Stray Processes

If you would like to ensure that all invoked processes have been faked throughout your individual test or complete test suite, you can call the preventStrayProcesses method. After calling this method, any processes that do not have a corresponding fake result will throw an exception rather than starting an actual process:

use Illuminate\Support\Facades\Process;
 
Process::preventStrayProcesses();
 
Process::fake([
    'ls *' => 'Test output...',
]);
 
// Fake response is returned...
Process::run('ls -la');
 
// An exception is thrown...
Process::run('bash import.sh');