1.\" 2.\" Sun Microsystems, Inc. gratefully acknowledges The Open Group for 3.\" permission to reproduce portions of its copyrighted documentation. 4.\" Original documentation from The Open Group can be obtained online at 5.\" http://www.opengroup.org/bookstore/. 6.\" 7.\" The Institute of Electrical and Electronics Engineers and The Open 8.\" Group, have given us permission to reprint portions of their 9.\" documentation. 10.\" 11.\" In the following statement, the phrase ``this text'' refers to portions 12.\" of the system documentation. 13.\" 14.\" Portions of this text are reprinted and reproduced in electronic form 15.\" in the SunOS Reference Manual, from IEEE Std 1003.1, 2004 Edition, 16.\" Standard for Information Technology -- Portable Operating System 17.\" Interface (POSIX), The Open Group Base Specifications Issue 6, 18.\" Copyright (C) 2001-2004 by the Institute of Electrical and Electronics 19.\" Engineers, Inc and The Open Group. In the event of any discrepancy 20.\" between these versions and the original IEEE and The Open Group 21.\" Standard, the original IEEE and The Open Group Standard is the referee 22.\" document. The original Standard can be obtained online at 23.\" http://www.opengroup.org/unix/online.html. 24.\" 25.\" This notice shall appear on any product containing this material. 26.\" 27.\" The Berkeley software License Agreement specifies the terms and conditions 28.\" for redistribution. 29.\" 30.\" 31.\" Copyright (c) 1980 Regents of the University of California. 32.\" All rights reserved. 33.\" Portions Copyright (c) 1992, X/Open Company Limited All Rights Reserved. 34.\" Copyright (c) 2008, Sun Microsystems, Inc. All Rights Reserved. 35.\" Copyright 2014 Garrett D'Amore <garrett@damore.org> 36.\" 37.Dd "Aug 16, 2014" 38.Dt USLEEP 3C 39.Os 40.Sh NAME 41.Nm usleep 42.Nd suspend execution for interval in microseconds 43.Sh SYNOPSIS 44.In unistd.h 45.Ft int 46.Fn usleep "useconds_t useconds" 47.Sh DESCRIPTION 48The 49.Fn usleep 50function suspends the caller from execution for the number 51of microseconds specified by the 52.Fa useconds 53argument. 54The actual suspension time might be less than requested because any caught 55signal will terminate 56.Fn usleep 57following execution of that signal's catching routine. 58The suspension time might be longer than requested by an arbitrary amount 59because of the scheduling of other activity in the system. 60.Lp 61If the value of 62.Fa useconds 63is 0, then the call has no effect. 64.Lp 65The use of the 66usleep 67function has no effect on the action or blockage 68of any signal. 69In a multithreaded process, only the invoking thread is suspended from 70execution. 71.Sh RETURN VALUES 72On completion, 73.Fn usleep 74returns 0. 75There are no error returns. 76.Sh ERRORS 77No errors are returned. 78.Sh USAGE 79The 80.Fn usleep 81function is included for its historical usage and is Obsolete. 82The 83.Xr nanosleep 3C 84function is preferred over this function. 85.Sh INTERFACE STABILITY 86.Sy Obsolete Standard . 87.Sh MT-LEVEL 88.Sy Safe . 89.Sh SEE ALSO 90.Xr nanosleep 3C , 91.Xr sleep 3C , 92.Xr unistd.h 3HEAD , 93.Xr standards 5 94.Sh STANDARDS 95The 96.Fn usleep 97function is available in the following compilation environments. 98See 99.Xr standards 5 . 100.Lp 101.Bl -bullet -compact 102.It 103.St -xpg4.2 104.It 105.St -susv2 106.It 107.St -susv3 108.El 109.Lp 110It is marked obsolete in 111.St -susv3 , and was removed from 112.St -p1003.1-2008 . 113