Killing processes opened with popen()?

I’m opening a long-running process with popen(). For debugging, I’d like to terminate the process before it has completed. Calling pclose() just blocks until the child completes.

How can I kill the process? I don’t see any easy way to get the pid out of the resource that popen() returns so that I can send it a signal.

I suppose I could do something kludgey and try to fudge the pid into the output using some sort of command-line hackery…

Here is Solutions:

We have many solutions to this problem, But we recommend you to use the first solution because it is tested & true solution that will 100% work for you.

Solution 1

Well, landed on a solution: I switched back to proc_open() instead of popen(). Then it’s as simple as:

$s = proc_get_status($p);
posix_kill($s['pid'], SIGKILL);

Solution 2

Just send a kill (or abort) signal using kill function:

Solution 3

You can find the pid, and checks that you’re really its parent by doing:

// Find child processes according to current pid
$res = trim(exec('ps -eo pid,ppid |grep "'.getmypid().'" |head -n2 |tail -n1'));
if (preg_match('~^(\d+)\s+(\d+)$~', $res, $pid) !== 0 && (int) $pid[2] === getmypid())
    // I'm the parent PID, just send a KILL
    posix_kill((int) $pid[1], 9);

It’s working quite well on a fast-cgi PHP server.

Note: Use and implement solution 1 because this method fully tested our system.
Thank you 🙂

All methods was sourced from or, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0

Leave a Reply