4956af2a8f
PR: 253395 Reported by: zegang.luo@qq.com MFC after: 3 days Sponsored by: The FreeBSD Foundation
81 lines
2.8 KiB
Groff
81 lines
2.8 KiB
Groff
.\" Copyright (c) 1986, 1991, 1993
|
|
.\" The Regents of the University of California. All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" 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
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\" 3. Neither the name of the University nor the names of its contributors
|
|
.\" may be used to endorse or promote products derived from this software
|
|
.\" without specific prior written permission.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\" SUCH DAMAGE.
|
|
.\"
|
|
.\" @(#)usleep.3 8.1 (Berkeley) 6/4/93
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd February 11, 2021
|
|
.Dt USLEEP 3
|
|
.Os
|
|
.Sh NAME
|
|
.Nm usleep
|
|
.Nd suspend thread execution for an interval measured in microseconds
|
|
.Sh LIBRARY
|
|
.Lb libc
|
|
.Sh SYNOPSIS
|
|
.In unistd.h
|
|
.Ft int
|
|
.Fn usleep "useconds_t microseconds"
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Fn usleep
|
|
function suspends execution of the calling thread until either
|
|
.Fa microseconds
|
|
microseconds have elapsed or a signal is delivered to the thread and its
|
|
action is to invoke a signal-catching function or to terminate the
|
|
process.
|
|
System activity may lengthen the sleep by an indeterminate amount.
|
|
.Pp
|
|
This function is implemented using
|
|
.Xr nanosleep 2
|
|
by pausing for
|
|
.Fa microseconds
|
|
microseconds or until a signal occurs.
|
|
Consequently, in this implementation,
|
|
sleeping has no effect on the state of process timers,
|
|
and there is no special handling for SIGALRM.
|
|
.Sh RETURN VALUES
|
|
.Rv -std usleep
|
|
.Sh ERRORS
|
|
The
|
|
.Fn usleep
|
|
function
|
|
will fail if:
|
|
.Bl -tag -width Er
|
|
.It Bq Er EINTR
|
|
A signal was delivered to the calling thread and its
|
|
action was to invoke a signal-catching function.
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr nanosleep 2 ,
|
|
.Xr sleep 3
|
|
.Sh HISTORY
|
|
The
|
|
.Fn usleep
|
|
function appeared in
|
|
.Bx 4.3 .
|