NetBSD/lib/libc/gen/usleep.3

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.\" $NetBSD: usleep.3,v 1.11 2000/08/21 23:23:23 soren Exp $
.\"
.\" Copyright (c) 1986, 1991, 1993
.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" modification, are permitted provided that the following conditions
.\" are met:
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.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
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.\" must display the following acknowledgement:
.\" This product includes software developed by the University of
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.\" may be used to endorse or promote products derived from this software
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.\" @(#)usleep.3 8.1 (Berkeley) 6/4/93
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.\"
.Dd June 4, 1993
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.Dt USLEEP 3
.Os
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.Sh NAME
.Nm usleep
.Nd suspend execution for interval of microseconds
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.Sh LIBRARY
.Lb libc
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.Sh SYNOPSIS
.Fd #include <unistd.h>
.Ft int
.Fn usleep "useconds_t microseconds"
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.Sh DESCRIPTION
The
.Fn usleep
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function
suspends execution of the calling process
until either the number of microseconds specified by
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.Fa microseconds
have elapsed or a signal is delivered to the calling process and its
action is to invoke a signal catching function or to terminate the
process. The suspension time may be longer than requested due to the
scheduling of other activity by the system.
.Pp
The
.Fa microseconds
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argument must be less than 1,000,000. If the value of
.Fa microseconds
is 0, then the call has no effect.
.Sh RETURN VALUE
On successful completition,
.Fn usleep
returns 0. Otherwhise, it returns -1 and sets errno to indicate the error.
.Sh ERRORS
The
.Fn usleep
function may fail if:
.Bl -tag -width Er
.It Bq Er EINVAL
The
.Fa microseconds
interval specified 1,000,000 or more microseconds.
.El
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.Sh SEE ALSO
.Xr nanosleep 2 ,
.Xr sleep 3
.Sh STANDARDS
The
.Fn usleep
function conforms to
.St -xpg4.2 .
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.Sh HISTORY
The
.Fn usleep
function appeared in
.Bx 4.3 .