php exec() background process issues

Question

I'm trying to process a file in the background with the following command, but it does nothing.

exec("php csv.php $file $user > /dev/null &", $output);

If I remove > /dev/null & then the file processes, but not in the background.

exec("php csv.php $file $user", $output);

Any ideas?

Answer 1

Note:

If a program is started with this function, in order for it to continue running in the background, the output of the program must be redirected to a file or another output stream. Failing to do so will cause PHP to hang until the execution of the program ends.

http://php.net/manual/en/function.exec.php

so:

exec("php csv.php $file $user > /dev/null &"); // no $output