Last reboot

Want to find out how long your computer has been on since the last reboot? Simply enter into a terminal:

last reboot

It will actually give you a list of the last few reboots, with the latest on top, and display the results as so:

Fri Aug 21 10:43 – 10:24 (5+23:40)

If you just want the last login, and happy to have is displayed like 2009-08-21 10:43, simply enter:

who -b

THANKS: Ubuntu Genius