uptime is one of the linux commands which allows you to quickly
confirm how long your system has been up and running
since it was last rebooted or powered on.
how you use it:
10:06:25 up 22:43, 4 users, load average: 0.39, 0.23, 0.27
single line of output gives you all the uptime information you may need:
10:06:25 – that’s the current Unix system time.
up 22:43 hours – shows for how long your system has been running.
4 users – number of users currently logged into your system.
load average: 0.39, 0.23, 0.27 – the average CPU load .
Now you can find out how long your system has been up?