sleep(1)

NAME

sleep — suspend execution for an interval

sleep time

sleep suspends execution for time seconds. It is used to execute a command after a certain amount of time, as in:

(sleep 105; command)& 

or to execute a command periodically, as in:

while true 
do 
    command 
    sleep 37 
done 

sleep exits with one of the following values:

0: The execution was successfully suspended for time seconds, or a SIGALRM signal was received.
>0: If the time operand is missing, is not a decimal integer, is negative, or is greater than UINT_MAX, sleep returns with exit status 2.

sleep: SVID2, SVID3, XPG2, XPG3, XPG4, POSIX.2