last - show listing of last logged in users.
Display who has recently logged in or out:
last
List a particular user last logged in:
last james
Hide the hostname field:
last -R
Display complete login and logout times:
last -F
Display full user/domain names:
last -w
Display last reboot time:
last -x reboot
Display last shutdown time:
last -x shutdown
Display who was logged in at a particular time:
last -t YYYYMMDDHHMMSS