To get the time elapsed since last system boot in hh:mm:ss format, you can use:

awk '{print int($1/3600)":"int(($1%3600)/60)":"int($1%60)}' /proc/uptime

/proc/uptime pseudo-file contains two numbers:

• The first number is how long the system has been up in seconds.


• The second number is how much of that time the machine has spent idle in seconds.

So, using awk you can take firs number and convert it in hh:mm:ss format.