How can one determine the exact file permissions needed for a specific file in PHP?

To determine the exact file permissions needed for a specific file in PHP, you can use the `fileperms()` function to retrieve the current permissions of the file. You can then compare these permissions with the desired permissions using the `chmod()` function to set the correct permissions.

$filename = 'example.txt';

// Get current file permissions
$currentPermissions = fileperms($filename);

// Desired permissions (e.g. read, write, execute for owner, group, and others)
$desiredPermissions = 0644; // For read and write permissions for owner, read permissions for group and others

// Set the desired permissions
chmod($filename, $desiredPermissions);