Today we are going to see how to run Linux server commands as root using PHP script. We can run commands easily using shell_exec()function. We can also run using exec().

From StackOverflow: shell_exec returns all of the output streams as a string. exec returns the last line of the output by default, but can provide all output as an array specified as the second parameter.

Enable shell_exec() Function

By default shell_exec() function is disabled. First, we need to enable this. We have edit php.ini file. Let’s find out the php.ini file location by typing this command:

php --ini

If we run this command, the output should look like:

Configuration File (php.ini) Path: /etc
Loaded Configuration File: /etc/php.ini

Now open php.ini file and you can see disable_functions like this:

disable_functions=show_source, system, shell_exec, exec

Let’s remove shell_exec and exec from the list. Then it should look like:

disable_functions=show_source, system

Restart the web server:

# Apache
sudo systemctl restart httpd
# PHP-FPM
sudo /etc/init.d/php-fpm restart

We have enabled the shell_exec function.

Set Permission to Execute Command in PHP File

We need to run:

visudo

I’m going to set permission for the username www-data to execute all commands in PHP file. Add this line to the opened file:

www-data ALL=NOPASSWD: ALL

We have given full access to run commands in PHP. You can give a specific function to work in a PHP file. This is an example of this:

www-data ALL=NOPASSWD: /usr/bin/service

You need to replace www-data with your username. Now save (!wq) the file and try to run Linux command.

Run Commands in PHP

Let’s try to run a command as root:

<?php
// check shell_exec is installed
if(!function_exists('shell_exec')) {
    echo "shell_exec is'nt enabled";
}

// run a command
$output = shell_exec('sudo php -v');
echo "<pre>$output</pre>";

The output:

PHP 7.2.8 (cli) (built: Jul 17 2018 09:50:46) ( NTS )
Copyright (c) 1997-2018 The PHP Group
Zend Engine v3.2.0, Copyright (c) 1998-2018 Zend Technologies