SLEEP
NAME SYNOPSIS DESCRIPTION RETURN VALUE CONFORMING TO BUGS SEE ALSO
sleep - Sleep for the specified number of seconds
#include seconds);
sleep() makes the current process sleep until seconds seconds have elapsed or a signal arrives which is not ignored.
Zero if the requested time has elapsed, or the number of seconds left to sleep.
POSIX.1
sleep() may be implemented using SIGALRM; mixing calls to alarm() and sleep() is a bad idea.
Using longjmp() from a signal handler or modifying the handling of SIGALRM while sleeping will cause undefined results.
6 pages link to sleep(3):