uptime

uptime shows how long the system has been running, along with a few related figures.

uptime [options]

$ uptime
 14:32:08  up 6 days,  3:21,  2 users,  load average: 0.18, 0.24, 0.21

The default line packs in four things:

the current time;
how long the system has been up;
how many users are currently logged in;
the load average — a rough measure of how busy the system has been over the last 1, 5, and 15 minutes.

Options

Option	Effect
`-p`, `--pretty`	Show just the uptime, in a readable phrase — `up 6 days, 3 hours, 21 minutes`.
`-s`, `--since`	Show the date and time the system started, rather than how long ago that was.

uptime returns 0, or non-zero if the boot time could not be read.