Ah I forgot: removing the "2>&1" part everything works fine.

Nuno, is this still valid bug? I can't reproduce it even with PHP 5.2.6..

Yes, I'm still able to reproduce it. In some systems you may need higher proviledges in order to reproduce this bug.

We're having the same problem by starting java.
(the java process starts as root and forks itself to another userid)

the 'sh' gets killed but our java process keeps on running

Well I've also just found this problem.
I run sh script via proc_open and if this script runs child processes that could 
hang, they will not be killed if you run proc_terminate().

To fix it I use:

// As soon proc is started
$status = proc_get_status($proc);
posix_setpgid($status['pid'], $status['pid']);

// When I need to kill it
posix_kill(-$status['pid'], 9); // sends SIGKILL to all processes inside group
proc_close($proc);

Why not to add this into proc_terminate() implementation?

I've happened on this same issue also, though I also find that proc_get_status returns only the pid of some /bin/sh wrapper.

I've tried on PHP 5.5 and 5.6,

Interesting to note is that the behaviour on OSX is quite easy to handle: there is no /bin/sh wrapper process at all in that case, but on Ubuntu (currently tested on lucid), you only ever have access to the /bin/sh proc: the process you actually started and the one that you care about is left running.

I'm going to work around this by having child processes write their own pids to a file and use those for signalling.

An easy workaround...

Instead of:

  $proc = proc_open('cat', ...);

Use this:

  $proc = proc_open('exec cat', ...);

It tells the shell to replace its own process with the command being executed rather than forking a child process. This way you can properly kill the command using proc_terminate($proc).

I believe this should be addressed in PHP 7.4 by writing:

$proc = proc_open(
    ['php', '-r', 'while(1){}'],
    [2 => ['redirect', 1]],
    $pipes);
var_dump(proc_terminate($proc));

This will not go through a shell, and as such the created process will be terminated directly.

Please let me know if there are still issues when going through the shell-free interface.

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The bug is reproducible on 7.4.15, Fedora Workstation 33. Any fixes?

@machitgarha: To clarify, you're still seeing this issue when passing an *array* command to proc_open()? It is expected that this doesn't work when passing a *string* command, because those are invoked through a shell.

I cannot reproduce this on linux with PHP 8.x git master.. even when run thousands of times through a shell.. Im almost certainly missing something oe it was a bug in the shell...