Command to check the reboot date and time on Linux server

[email protected] [/]# who -b
system boot 2012-04-24 09:04

[email protected] [/]# last reboot | head -1
reboot system boot 2.6.18-308.1.1.e Tue Apr 24 09:04 (9+22:24)
[email protected] [/]#

[email protected] [/]# last -x|grep shutdown | head -1
shutdown system down 2.6.18-308.1.1.e Tue Apr 24 09:04 - 07:30 (9+22:25)
[email protected] [/]#