As Unix / Linux server administrator, we always need to know when is our last rebooted date and time. Actually, we are able to list out the system rebooted history by issue following command.

last reboot

Output

mkyong@mkyong:~$ last reboot
reboot   system boot  2.6.28-11-generi Thu Jul 16 21:42 - 23:46  (02:04)    
reboot   system boot  2.6.28-11-generi Sun Jul 12 07:38 - 12:58  (05:20)    
reboot   system boot  2.6.28-11-generi Sun Jul 12 07:36 - 07:37  (00:01)    
reboot   system boot  2.6.28-11-generi Wed Jul  8 21:34 - 21:45  (00:11)