Linux or Linux like mahine, the server running time can be seen using the command uptime. Here is an example:
[admin@devopsrun1 ~]$ uptime
20:42:14 up  7:33,  3 users,  load average: 0.00, 0.01, 0.05

Other helpful sys admin commands

Check who all are logged in to the system
The who command can display list of active users.
[admin@devopsrun1 ~]$ who
root     tty1         2019-11-11 19:37
root     pts/0        2019-11-11 20:04 (gateway)
root     pts/1        2019-11-11 20:25 (gateway)