Which command is used to send events to the udev program?

The command used to send events to the udev program is udevadm. This utility is a key tool in managing device events in the Linux operating system, particularly with the udev subsystem, which is responsible for dynamic device management.

When a device is added or removed from the system, udev generates events that allow the kernel to recognize and configure these devices dynamically. The udevadm command facilitates the interaction with the udev daemon, enabling users to trigger device events, monitor them, or control their behavior. For instance, it can be used to send events manually, retrieve device information, and watch for device adds or removes in real-time, making it essential for managing hardware devices in a Linux environment.

In contrast, other options, while related to system management, do not specifically deal with sending events to udev. For example, udevctrl is not a standard command in Linux distributions for managing udev, and systemd is an init system and service manager that handles services and system processes rather than device events directly. Initctl is associated with Upstart, an event-based replacement for the init daemon, which is also not directly related to udev event management.