What are best practices for setting file permissions and user privileges when working with PHP scripts that interact with server files?

When working with PHP scripts that interact with server files, it is important to set appropriate file permissions and user privileges to ensure security and prevent unauthorized access. Best practices include setting file permissions to restrict access to only necessary users, avoiding using overly permissive permissions such as 777, and utilizing user privileges to limit the actions that PHP scripts can perform on files.

// Set appropriate file permissions (e.g. 644 for files, 755 for directories)
chmod('/path/to/file', 0644);

// Set user privileges to restrict access to specific users
chown('/path/to/file', 'username');