What are the best practices for handling user input in PHP scripts to prevent security vulnerabilities like command injection?

To prevent security vulnerabilities like command injection in PHP scripts, it is crucial to sanitize and validate user input before using it in any commands or queries. This can be achieved by using functions like `filter_input()` or `mysqli_real_escape_string()` to sanitize input data and by validating input against expected formats or values. Additionally, utilizing prepared statements for database queries can help prevent SQL injection attacks. 

$user_input = filter_input(INPUT_POST, 'user_input', FILTER_SANITIZE_STRING);

// Or using mysqli_real_escape_string
$user_input = mysqli_real_escape_string($connection, $_POST['user_input']);

// Validate input against expected format or values
if (preg_match('/^[a-zA-Z0-9]+$/', $user_input)) {
    // Proceed with using the sanitized and validated user input
} else {
    // Handle invalid input
}

Keywords

input validation sanitization prepared statements htmlspecialchars escapeshellarg

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