1.\" $NetBSD: usleep.3,v 1.16 2002/10/01 16:48:35 wiz 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. All advertising materials mentioning features or use of this software 15.\" must display the following acknowledgement: 16.\" This product includes software developed by the University of 17.\" California, Berkeley and its contributors. 18.\" 4. Neither the name of the University nor the names of its contributors 19.\" may be used to endorse or promote products derived from this software 20.\" without specific prior written permission. 21.\" 22.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32.\" SUCH DAMAGE. 33.\" 34.\" @(#)usleep.3 8.1 (Berkeley) 6/4/93 35.\" 36.Dd June 4, 1993 37.Dt USLEEP 3 38.Os 39.Sh NAME 40.Nm usleep 41.Nd suspend execution for interval of microseconds 42.Sh LIBRARY 43.Lb libc 44.Sh SYNOPSIS 45.Fd #include \*[Lt]unistd.h\*[Gt] 46.Ft int 47.Fn usleep "useconds_t microseconds" 48.Sh DESCRIPTION 49The 50.Fn usleep 51function 52suspends execution of the calling process 53until either the number of microseconds specified by 54.Fa microseconds 55have elapsed or a signal is delivered to the calling process and its 56action is to invoke a signal catching function or to terminate the 57process. 58The suspension time may be longer than requested due to the 59scheduling of other activity by the system. 60.Pp 61The 62.Fa microseconds 63argument must be less than 1,000,000. 64If the value of 65.Fa microseconds 66is 0, then the call has no effect. 67.Sh RETURN VALUES 68On successful completion, 69.Fn usleep 70returns 0. 71Otherwise, it returns \-1 and sets 72.Va errno 73to indicate the error. 74.Sh ERRORS 75The 76.Fn usleep 77function may fail if: 78.Bl -tag -width Er 79.It Bq Er EINVAL 80The 81.Fa microseconds 82interval specified 1,000,000 or more microseconds. 83.El 84.Sh SEE ALSO 85.Xr nanosleep 2 , 86.Xr sleep 3 87.Sh STANDARDS 88The 89.Fn usleep 90function conforms to 91.St -xpg4.2 . 92.Sh HISTORY 93The 94.Fn usleep 95function appeared in 96.Bx 4.3 . 97