SLEEP(3) Linux Programmer's Manual SLEEP(3)
NAME
sleep - Sleep for the specified number of seconds
SYNOPSIS
#include<unistd.h>
unsignedintsleep(unsignedint seconds);
DESCRIPTION
sleep() makes the current process sleep until seconds seconds have
elapsed or a signal arrives which is not ignored.
RETURNVALUE
Zero if the requested time has elapsed, or the number of seconds left
to sleep.
CONFORMINGTO
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.
SEEALSO
signal(2), alarm(2)
GNU 1993-04-07 SLEEP(3)
Take our 
