rfkill

rfkill is a subsystem in the Linux kernel that provides a unified interface for managing wireless devices. It allows users and administrators to enable or disable wireless hardware such as Wi-Fi, Bluetooth, and WWAN (mobile broadband). The primary purpose of rfkill is to provide a consistent way to control these devices, regardless of the underlying hardware or driver.

The rfkill subsystem exposes a set of ioctls (input/output control) that can be used by userspace applications or utilities to query the status of wireless devices and to toggle their state. This functionality is crucial for power management, security, and user convenience. For example, users can quickly turn off Wi-Fi to save battery life or disable all wireless radios before boarding an airplane.

Two main types of blocking exist within rfkill: soft block and hard block. A soft block is a software-level disablement that can be controlled by userspace tools. A hard block, on the other hand, is a hardware-level disablement, often controlled by a physical switch on the device or by firmware. rfkill can detect and manage both types of blocks.

Users typically interact with rfkill through command-line utilities like rfkill (which is often part of the same package) or through graphical interfaces provided by desktop environments. These tools allow users to list all wireless devices, their current status (soft/hard blocked or soft/hard enabled), and to change their state.