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@(#)sleep.3 8.1 (Berkeley) 6/4/93
.Dd June 4, 1993 .Dt SLEEP 3 .Os .Sh NAME .Nm sleep .Nd suspend process execution for interval of seconds .Sh SYNOPSIS .Fd #include <unistd.h> .Ft u_int .Fn sleep "u_int seconds" .Sh DESCRIPTION The .Fn sleep function suspends execution of the calling process for .Fa seconds of time. System activity or time spent in processing the call may lengthen the sleep by a second.
p If a timer is already running on the process its state is unaltered by this sleep implementation. If the value .Fa seconds is more than or equal to the remaining clock time for the running timer, the sleep time is set to the remaining clock time.
p This function is implemented using .Xr signanosleep 2 by pausing for .Fa seconds of time or until any signal occurse. For compatibility reasons during .Fn sleep call SIGALRM handler is temporary set to the function which does nothing but returns. .Sh RETURN VALUES The .Fn sleep function returns the number of seconds remaining to complete the operation. If sleep is interrupted or cannot allocate a timer it may will return the value needed to be passed to a subsequent sleep to complete the necessary delay. .Fn sleep repeatedly until it returns zero may busy-wait until a timer is available. .Sh SEE ALSO .Xr signal 3 , .Xr signanosleep 2 , .Xr usleep 3 .Sh HISTORY A .Fn sleep function appeared in .At v7 .