sleep(3C)

NAME
     sleep - suspend execution for interval

SYNOPSIS
     #include <unistd.h>

     unsigned sleep (unsigned seconds);

DESCRIPTION
     The current thread is suspended from execution for the number of seconds
     specified by the argument.  The actual suspension time may be less than
     that requested because any caught signal will terminate the sleep
     following execution of that signal's catching routine.  Also, the
     suspension time may be longer than requested by an arbitrary amount due
     to the scheduling of other activity in the system.  The value returned by
     sleep will be the ``unslept'' amount (the requested time minus the time
     actually slept) in case of premature arousal due to a caught signal.

NOTES
     Unlike previous implementations, sleep is implemented with the sginap(2)
     system call rather than with alarm(2). Therefore, there are no unusual
     side effects with the SIGALRM signal; its effect is like that of any
     other signal.

SEE ALSO
     alarm(2), sginap(2), pause(2), sigaction(2), sigset(2)