Any equivalent to subprocess in PHP?

Question

In Java and Python, you have the ProcessBuilder or subprocess modules that let you easily start a process using unescaped strings e.g. ["ls", "some unescaped directory name"] - they also give you powerful tools like access to read from stdout, stderr. Is there any equivalent feature of PHP that is more intelligent and useful than just exec()?

Answer 1

The closest equivalent that gives you access to stdin, stdout, and stderr, with two-way communication, would be proc_open().

Here's the example from the docs:

<?php
$descriptorspec = array(
   0 => array("pipe", "r"),  // stdin is a pipe that the child will read from
   1 => array("pipe", "w"),  // stdout is a pipe that the child will write to
   2 => array("file", "/tmp/error-output.txt", "a") // stderr is a file to write to
);

$cwd = '/tmp';
$env = array('some_option' => 'aeiou');

$process = proc_open('php', $descriptorspec, $pipes, $cwd, $env);

if (is_resource($process)) {
    // $pipes now looks like this:
    // 0 => writeable handle connected to child stdin
    // 1 => readable handle connected to child stdout
    // Any error output will be appended to /tmp/error-output.txt

    fwrite($pipes[0], '<?php print_r($_ENV); ?>');
    fclose($pipes[0]);

    echo stream_get_contents($pipes[1]);
    fclose($pipes[1]);

    // It is important that you close any pipes before calling
    // proc_close in order to avoid a deadlock
    $return_value = proc_close($process);

    echo "command returned $return_value\n";
}
?>

If you only need stdout and stdin, you can use popen().

This is my modified example, since the manual's sucks:

<?php
$handle = popen('/path/to/executable', 'r');

$lines = [];
while (!feof($handle))
{
    $lines[] = fgets($handle);
}

pclose($handle);

This will read the output of /path/to/executable into an array of lines of output.

You also asked about escaping arguments. You can do that with escapeshellarg():

$escapedArg = escapeshellarg($arg);