Sorry I was busy for the two days and couldn’t post here. And my rescheduled exams start from 16th Dec till 27th Dec.
sleep/usleep — Sleep for a specified amount of time
Summary :
Sleep will introduce a delay for a specified seconds (Seconds may be an arbitrary floating point number). usleep sleeps some no of micro-seconds (default is 1).
Examples :
$ sleep 6 — Sleep for 6 Seconds.
$ sleep 6s — Sleep for 6 Seconds (Default).
$ sleep 6m — Sleep for 6 Minutes.
$ sleep 6h — Sleep for 6 Hours.
$ sleep 6d — Sleep for 6 Days.
$ sleep 10.5 — sleep for 10.5 Seconds.
$ usleep 200 — Sleep for 200 micro Seconds.
Sleep may NOT give a very accurate result on many machines.
Read : man sleep, usleep