'\" te
.\" Copyright (c) 2007, Sun Microsystems, Inc. All Rights Reserved.
.\" Copyright (c) 1980 Regents of the University of California. All rights reserved.  The Berkeley software License Agreement specifies the terms and conditions for redistribution.
.TH SLEEP 3UCB "Oct 30, 2007"
.SH NAME
sleep \- suspend execution for interval
.SH SYNOPSIS
.LP
.nf
\fB/usr/ucb/cc\fR [ \fIflag\fR ... ] \fIfile\fR ...

\fBint\fR \fBsleep\fR(\fIseconds\fR)
\fBunsigned\fR \fIseconds\fR;
.fi

.SH DESCRIPTION
.sp
.LP
\fBsleep()\fR suspends the current process from execution for the number of
seconds specified by the argument.  The actual suspension time may be up to 1
second less than that requested, because scheduled wakeups occur at fixed
1-second intervals, and may be an arbitrary amount longer because of other
activity in the system.
.sp
.LP
\fBsleep()\fR is implemented by setting an interval timer and pausing until it
expires.  The previous state of this timer is saved and restored.  If the sleep
time exceeds the time to the expiration of the previous value of the timer, the
process sleeps only until the timer would have expired, and the signal which
occurs with the expiration of the timer is sent one second later.
.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(5) for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
MT-Level	Async-Signal-Safe
.TE

.SH SEE ALSO
.sp
.LP
\fBalarm\fR(2), \fBgetitimer\fR(2), \fBlongjmp\fR(3C), \fBsiglongjmp\fR(3C),
\fBsleep\fR(3C), \fBusleep\fR(3C), \fBattributes\fR(5)
.SH NOTES
.sp
.LP
Use of these interfaces should be restricted to only applications written on
BSD platforms.  Use of these interfaces with any of the system libraries or in
multi-thread applications is unsupported.
.sp
.LP
\fBSIGALRM\fR should \fInot\fR be blocked or ignored during a call to
\fBsleep()\fR. Only a prior call to \fBalarm\fR(2) should generate
\fBSIGALRM\fR for the calling process during a call to \fBsleep()\fR. A
signal-catching function should \fInot\fR interrupt a call to \fBsleep()\fR to
call \fBsiglongjmp\fR(3C) or \fBlongjmp\fR(3C) to restore an environment saved
prior to the \fBsleep()\fR call.
.SH WARNINGS
.sp
.LP
\fBsleep()\fR is slightly incompatible with \fBalarm\fR(2). Programs that do
not execute for at least one second of clock time between successive calls to
\fBsleep()\fR indefinitely delay the alarm signal. Use \fBsleep\fR(3C). Each
\fBsleep\fR(3C) call postpones the alarm signal that would have been sent
during the requested sleep period to occur one second later.