To check user activity, and receive information such as reboot, boot, and
kernel version, you can use the last command.
The kernel version is the central component to the operating system, and is
essential for memory, process, task, and disk management.
$ last
charlie pts/8 10.144.120.74 Wed Mar 21 09:20 still logged in
reboot system boot 4.4.0-116-generi Thu Mar 15 15:06 still running