I can't add an at command from php. Please help.

[SLSCoder]

Ubuntu 20.04 apache2 php 8.0.14 php-fpm

I'm trying to execute an at command from php.
The code is:

$out = shell_exec('echo mkdir /var/www/test | at now +1 minutes');
echo $out . "<br>";

If I run that command from the command line it works fine.

When I run it from php I get nothing back into the $out variable and no directory is created.

How can I run an at command from php?

[SLSCoder]

I should add that:
The file /etc/at.deny does not include www-data (which is $_Server["user"])
The file /etc/at.allow does include www-data.

 

[SLSCoder]

I figured this out.
The problem was not with the at command, the user www-data did not have permissions to create the directory.

This is resolved.

 

[gizmola]

A couple of notes/suggestions for you:

First, shell_exec is equivalent to using backtics, inherited from the bourne bash shell.

$out = `echo mkdir /var/www/test | at now +1 minutes`;

I can see you have a contrived example, but if you actually want to depend on os return codes from the command you have to use exec, as it allows for the passing of an optional return code parameter, which in many cases is probably a preferable way to determine whether your commands ran successfully or had errors.