1.\" $NetBSD: usleep.3,v 1.19 2010/04/29 17:29:56 jruoho 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.\" @(#)usleep.3 8.1 (Berkeley) 6/4/93 31.\" 32.Dd April 29, 2010 33.Dt USLEEP 3 34.Os 35.Sh NAME 36.Nm usleep 37.Nd suspend execution for interval of microseconds 38.Sh LIBRARY 39.Lb libc 40.Sh SYNOPSIS 41.In unistd.h 42.Ft int 43.Fn usleep "useconds_t microseconds" 44.Sh DESCRIPTION 45The 46.Fn usleep 47function 48suspends execution of the calling process 49until either the number of microseconds specified by 50.Fa microseconds 51have elapsed or a signal is delivered to the calling process and its 52action is to invoke a signal catching function or to terminate the 53process. 54The suspension time may be longer than requested due to the 55scheduling of other activity by the system. 56.Pp 57The 58.Fa microseconds 59argument must be less than 1,000,000. 60If the value of 61.Fa microseconds 62is 0, then the call has no effect. 63.Sh RETURN VALUES 64On successful completion, 65.Fn usleep 66returns 0. 67Otherwise, it returns \-1 and sets 68.Va errno 69to indicate the error. 70.Sh ERRORS 71The 72.Fn usleep 73function may fail if: 74.Bl -tag -width Er 75.It Bq Er EINVAL 76The 77.Fa microseconds 78interval specified 1,000,000 or more microseconds. 79.El 80.Sh SEE ALSO 81.Xr nanosleep 2 , 82.Xr sleep 3 83.Sh STANDARDS 84The 85.Fn usleep 86function conforms to 87.St -xpg4.2 . 88It later appeared in the 89.Tn POSIX 90standard, but in 91.St -p1003.1-2004 92it was marked as legacy and the use of 93.Xr nanosleep 2 94was recommended instead. 95The 96.St -p1003.1-2008 97revision removed 98.Fn usleep 99from the specification. 100.Sh HISTORY 101The 102.Fn usleep 103function appeared in 104.Bx 4.3 . 105