What is the purpose of using shell_exec in PHP and what potential security risks does it pose?

The purpose of using shell_exec in PHP is to execute shell commands from within a PHP script. However, using shell_exec can pose security risks, as it allows for the execution of arbitrary commands on the server, potentially leading to vulnerabilities such as command injection attacks. To mitigate the security risks associated with using shell_exec in PHP, it is recommended to validate and sanitize any user input that is passed to the shell command. This can help prevent malicious commands from being executed on the server.

$user_input = $_POST['user_input'];
$validated_input = escapeshellarg($user_input);
$output = shell_exec("ls " . $validated_input);
echo $output;