What are the potential security risks of using PHP to execute shell scripts?

One potential security risk of using PHP to execute shell scripts is the possibility of command injection attacks. This occurs when user input is not properly sanitized and allows malicious commands to be executed on the server. To mitigate this risk, it is essential to validate and sanitize all user input before using it in shell commands.

$user_input = $_POST['input']; // Assuming user input is coming from a form field

// Validate and sanitize user input
$clean_input = escapeshellarg($user_input);

// Execute shell command with sanitized input
$output = shell_exec("your_script.sh $clean_input");