What is the potential risk of directly executing PHP commands from a text field without saving them to a file?

Executing PHP commands directly from a text field without saving them to a file can pose a significant security risk, as it opens the door to code injection attacks. To mitigate this risk, you should always sanitize and validate user input before executing it as PHP code. One way to do this is by using functions like `htmlspecialchars()` or `filter_var()` to prevent malicious code from being executed.

// Sanitize and validate user input before executing it as PHP code
$user_input = $_POST['user_input']; // Assuming user input is received via POST method
$sanitized_input = htmlspecialchars($user_input);
eval($sanitized_input); // Execute the sanitized input as PHP code