1.\" Copyright (c) 1986, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 4. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" @(#)sleep.3 8.1 (Berkeley) 6/4/93 29.\" $FreeBSD$ 30.\" 31.Dd February 13, 1998 32.Dt SLEEP 3 33.Os 34.Sh NAME 35.Nm sleep 36.Nd suspend thread execution for an interval measured in seconds 37.Sh LIBRARY 38.Lb libc 39.Sh SYNOPSIS 40.In unistd.h 41.Ft unsigned int 42.Fn sleep "unsigned int seconds" 43.Sh DESCRIPTION 44The 45.Fn sleep 46function suspends execution of the calling thread until either 47.Fa seconds 48seconds have elapsed or a signal is delivered to the thread and its 49action is to invoke a signal-catching function or to terminate the 50thread or process. 51System activity may lengthen the sleep by an indeterminate amount. 52.Pp 53This function is implemented using 54.Xr nanosleep 2 55by pausing for 56.Fa seconds 57seconds or until a signal occurs. 58Consequently, in this implementation, 59sleeping has no effect on the state of process timers, 60and there is no special handling for SIGALRM. 61.Sh RETURN VALUES 62If the 63.Fn sleep 64function returns because the requested time has elapsed, the value 65returned will be zero. 66If the 67.Fn sleep 68function returns due to the delivery of a signal, the value returned 69will be the unslept amount (the requested time minus the time actually 70slept) in seconds. 71.Sh SEE ALSO 72.Xr nanosleep 2 , 73.Xr usleep 3 74.Sh STANDARDS 75The 76.Fn sleep 77function conforms to 78.St -p1003.1-90 . 79.Sh HISTORY 80A 81.Fn sleep 82function appeared in 83.At v7 . 84