1.\" $OpenBSD: sleep.3,v 1.18 2022/03/31 17:27:15 naddy Exp $ 2.\" 3.\" Copyright (c) 1986, 1991, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. Neither the name of the University nor the names of its contributors 15.\" may be used to endorse or promote products derived from this software 16.\" without specific prior written permission. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28.\" SUCH DAMAGE. 29.\" 30.Dd $Mdocdate: March 31 2022 $ 31.Dt SLEEP 3 32.Os 33.Sh NAME 34.Nm sleep 35.Nd suspend execution for an interval of seconds 36.Sh SYNOPSIS 37.In unistd.h 38.Ft unsigned int 39.Fn sleep "unsigned int seconds" 40.Sh DESCRIPTION 41The 42.Fn sleep 43function suspends execution of the calling thread until at least the 44given number of 45.Fa seconds 46have elapsed or an unmasked signal is delivered to the calling thread. 47.Pp 48This version of 49.Fn sleep 50is implemented with 51.Xr nanosleep 2 , 52so delivery of any unmasked signal will terminate the sleep early, 53even if 54.Dv SA_RESTART 55is set with 56.Xr sigaction 2 57for the interrupting signal. 58.Sh RETURN VALUES 59If 60.Fn sleep 61sleeps for the full count of 62.Fa seconds , 63it returns 0. 64Otherwise, 65.Fn sleep 66returns the number of seconds remaining from the original request. 67.Sh ERRORS 68The 69.Fn sleep 70function sets 71.Va errno 72to 73.Dv EINTR 74if it is interrupted by the delivery of a signal. 75.Sh SEE ALSO 76.Xr sleep 1 , 77.Xr nanosleep 2 , 78.Xr sigaction 2 79.Sh STANDARDS 80The 81.Fn sleep 82function conforms to 83.St -p1003.1-2008 . 84.Pp 85Setting 86.Va errno 87is an extension to that specification. 88.Sh HISTORY 89A 90.Fn sleep 91system call first appeared in 92.At v2 . 93In 94.At v7 , 95it was removed and replaced by a C library implementation based on 96.Xr signal 3 97and 98.Xr alarm 3 . 99For 100.Ox 2.1 , 101it was reimplemented as a wrapper around the 102.Xr nanosleep 2 103system call. 104