How to Escape characters while passing system command in PHP

Question

I have a Linux web server running a PHP/HTML page.

    for loop
    {
    $instruction= \"I\'m constructing the instruction here\";
    }
    $instruction = \"ls         


        

Answer 1

Make use of escapeshellcmd() in PHP

Something like..

$escaped_command = escapeshellcmd($command);
exec($escaped_command);

Alternatively, you could make use of escapeshellarg()

<?php
echo shell_exec('ls '.escapeshellarg($userdata));