How to get linux running time

How to get linux running time
1.Use command "uptime"
It will output like this:
17:11:40 up 60 days, 4:11, 1 users, load average: 0.00, 0.01, 0.00
Which means it runs 60 days

2.Get from file /proc/uptime
cat /proc/uptime
It will output like this:
5227796.94 565899.85
The first number 5227796.94 means the system running seconds. We can use the command "date" to count the system running date and time:
date -d "$(awk -F. '{print $1}' /proc/uptime) second ago" +"%Y-%m-%d %H:%M:%S"
It will output like this:
2008-11-09 11:50:31

Which means the server when to run.

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