sleep

sleep 
n

Causes the script to sleep for n seconds, or forever if no argument is given. It may be interrupted by sending the process a SIGALRM . The function returns the number of seconds actually slept. On some systems, the function sleeps till the "top of the second," so, for instance, a sleep 1 may sleep anywhere from 0 to 1 second, depending on when in the current second you started sleeping.