从 PHP 调用外部 shell 脚本并获取其进程 ID

Question

如何从 PHP 本身调用外部 shell 脚本（或者外部 PHP 脚本）并在同一脚本中获取其进程 ID？

Answer 1

$command =  'yourcommand' . ' > /dev/null 2>&1 & echo $!; ';

$pid = exec($command, $output);

var_dump($pid);

Answer 2

If you want to do this strictly using tools PHP gives you, rather than Unix-specific wizardry , you can do so with proc_open and proc_get_status , although the need to pass a descriptor spec into proc_open makes it unpleasantly verbose to use:

<?php

$descriptorspec = [
    0 => ['pipe', 'r'],
    1 => ['pipe', 'w'],
    2 => ['pipe', 'w']
];
$proc = proc_open('yourcommand', $descriptorspec, $pipes);
$proc_details = proc_get_status($proc);
$pid = $proc_details['pid'];

echo $pid;

Answer 3

For a cross-platform solution, check out symfony/process .

use Symfony\Component\Process\Process;
$process = new Process('sleep 100');
$process->start();
var_dump($process->getPid());

After you install symfony/process with composer ( composer require symfony/process ), you may need to update autoloading info with composer dump-autoload and then require the autoload with require __DIR__ . '/vendor/autoload.php'; require __DIR__ . '/vendor/autoload.php'; .

Notice also that you can get PID of a running process only. Refer to the documentation for API details.

Answer 4

What ended up working for me is using pgrep to get the PID of the command (or process name) executed after calling exec() in PHP.

exec($command);
$pid = exec("pgrep $command");

This will work for launching background processes too. However, you must remember to pipe the program's output to /dev/null or else PHP will hang. Also, when calling pgrep you can't include the pipe portion of the command:

$command = "bg_process -o someOption";
exec($command + " > /dev/null &"); //Separate the pipe and '&' from the command
$pid = exec("pgrep $command");

Note that if the system has multiple processes launched with the same exact command, it will return the PIDs of all processes which match the command given to pgrep . If you only pass in a process name, it will return all PIDs with that process name.