Running PHP script in background

Question

I am testing a php script that has been developed on an OS-X system at Debian and it behaves different there.

To reproduce it I wrote two scripts: parent.php and child.php:

parent.php:

#!/usr/bin/php
<?php

echo "parent started...\n";
shell_exec(__DIR__ . '/child.php &2>/dev/null &');
echo "parent finished.\n";

child.php:

#!/usr/bin/php
<?php

echo "child started...\n";
sleep(5);
echo "child finished.\n";

Running parent.php on OS-X I get back imediately the two output lines (parent started, parent finished). On Debian I get the "parent started..." line, then a delay of 5 seconds an then the "parent finished.". Running "./child.php &2>/dev/null &" in the shell gives me back the prompt imediately as expected. Any ideas how I can fix this?

While I'm sure it's just a shorthand I've never seen before, since you say it works, I usually write that exec line as {cmd} > /dev/null 2>&1 & - would be interested to know if that makes a difference. — DaveRandom
– DaveRandom, Commented Jan 17, 2012 at 17:12
Did you mean to suppress errors by &2>/dev/null or just want to suppress any output? — Shiplu Mokaddim
– Shiplu Mokaddim, Commented Jan 17, 2012 at 17:18

Shiplu Mokaddim · Accepted Answer · 2012-01-17 18:04:47Z

4

This is because &2> part. It may not be supported in all systems. Also in every shell (bash, sh, ksh etc).

Try this,

 exec("/bin/bash -c '/usr/bin/php /path/to/child.php 2> /dev/null' &");

If you want to suppress all the output use this,

 exec("/bin/bash -c '/usr/bin/php /path/to/child.php &> /dev/null ' &");

BASH-HOWTO

Just tested, exec("/usr/bin/php /path/to/child.php > /dev/null 2>&1 &") should work too.

edited Jan 17, 2012 at 18:04

answered Jan 17, 2012 at 17:17

Shiplu Mokaddim

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2 Comments

DaveRandom Over a year ago

Your last line is missing the & on the end to separate the child process from the parent

Shiplu Mokaddim Over a year ago

@dave Thanks. Missed it as I typed too quickly.

Nanocom · Accepted Answer · 2012-01-17 17:14:02Z

2

Try with exec() or system() instead of shell_exec, maybe shell_exec has not the same behavior on different OS.

answered Jan 17, 2012 at 17:14

Nanocom

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