redhat man page for sleep

SLEEP(3)						     Linux Programmer's Manual							  SLEEP(3)

NAME
       sleep - Sleep for the specified number of seconds

SYNOPSIS
       #include <unistd.h>

       unsigned int sleep(unsigned int seconds);

DESCRIPTION
       sleep() makes the current process sleep until seconds seconds have elapsed or a signal arrives which is not ignored.

RETURN VALUE
       Zero if the requested time has elapsed, or the number of seconds left to sleep.

CONFORMING TO
       POSIX.1

BUGS
       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.

SEE ALSO
       signal(2), alarm(2)

GNU
								    1993-04-07								  SLEEP(3)