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.\" 3. 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.Dd February 13, 1998 29.Dt SLEEP 3 30.Os 31.Sh NAME 32.Nm sleep 33.Nd suspend thread execution for an interval measured in seconds 34.Sh LIBRARY 35.Lb libc 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 either 44.Fa seconds 45seconds have elapsed or a signal is delivered to the thread and its 46action is to invoke a signal-catching function or to terminate the 47thread or process. 48System activity may lengthen the sleep by an indeterminate amount. 49.Pp 50This function is implemented using 51.Xr nanosleep 2 52by pausing for 53.Fa seconds 54seconds or until a signal occurs. 55Consequently, in this implementation, 56sleeping has no effect on the state of process timers, 57and there is no special handling for SIGALRM. 58.Sh RETURN VALUES 59If the 60.Fn sleep 61function returns because the requested time has elapsed, the value 62returned will be zero. 63If the 64.Fn sleep 65function returns due to the delivery of a signal, the value returned 66will be the unslept amount (the requested time minus the time actually 67slept) in seconds. 68.Sh SEE ALSO 69.Xr nanosleep 2 , 70.Xr usleep 3 71.Sh STANDARDS 72The 73.Fn sleep 74function conforms to 75.St -p1003.1-90 . 76.Sh HISTORY 77A 78.Fn sleep 79function appeared in 80.At v7 . 81