What command is used to request device events from the kernel using udevadm?

The command that requests device events from the kernel using udevadm is the one that enables system administrators to trigger events related to device management based on specific criteria or conditions. This command allows one to simulate device events, such as adding or removing hardware, which can be crucial for testing or debugging udev rules without the actual physical changes occurring in the system.

By using this command, you can specify which devices to trigger events for, effectively causing udev to process the rules associated with those devices as if they were being added or removed. This is particularly useful when you need to ensure that udev rules are working correctly and that the appropriate actions are taken automatically based on the events that are signaled to the kernel.

The other options provided do not serve the purpose of directly requesting device events from the kernel in the same manner. While commands like invoke and event can deal with actions or interactions involving udev, they do not provide the same functionality as triggering events that impact device management. The request option does not exist in the udev command set, making it invalid for this context.