How does the server administrator configure what is writable?

To configure what is writable on a server, the server administrator can use file permissions to control which users or processes can write to specific files or directories. This can be done by setting the appropriate permissions using the chmod command in the terminal or through a control panel interface provided by the hosting provider. By setting the correct permissions, the server administrator can ensure that only authorized users or processes have the ability to write to certain files or directories.

// Example: Set permissions to allow only the owner to write to a file
$filename = 'example.txt';
$ownerPermissions = 0600; // Owner has read and write permissions
chmod($filename, $ownerPermissions);