[apple/libc.git] / gen / usleep.3

.\" 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. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. 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: src/lib/libc/gen/usleep.3,v 1.18 2002/12/29 00:59:09 mike Exp $
.\"
.Dd February 13, 1998
.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
.Fo usleep
.Fa "useconds_t useconds"
.Fc
.Sh DESCRIPTION
The
.Fn usleep
function suspends execution of the calling thread until either
.Fa useconds
microseconds have elapsed
or a signal is delivered to the thread whose action
is to invoke a signal-catching function
or to terminate the thread or process.
The actual time slept may be longer, due to system latencies
and possible limitations in the timer resolution of the hardware.
.Pp
This function is implemented, using
.Xr nanosleep 2 ,
by pausing for
.Fa useconds
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 process 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 .
Commit	Line	Data
224c7076	1	.\" Copyright (c) 1986, 1991, 1993
e9ce8d39 A	2	.\" The Regents of the University of California. All rights reserved.
	3	.\"
	4	.\" Redistribution and use in source and binary forms, with or without
	5	.\" modification, are permitted provided that the following conditions
	6	.\" are met:
	7	.\" 1. Redistributions of source code must retain the above copyright
	8	.\" notice, this list of conditions and the following disclaimer.
	9	.\" 2. Redistributions in binary form must reproduce the above copyright
	10	.\" notice, this list of conditions and the following disclaimer in the
	11	.\" documentation and/or other materials provided with the distribution.
	12	.\" 3. All advertising materials mentioning features or use of this software
	13	.\" must display the following acknowledgement:
	14	.\" This product includes software developed by the University of
	15	.\" California, Berkeley and its contributors.
	16	.\" 4. Neither the name of the University nor the names of its contributors
	17	.\" may be used to endorse or promote products derived from this software
	18	.\" without specific prior written permission.
	19	.\"
	20	.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	21	.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	22	.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	23	.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	24	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	25	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	26	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	27	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	28	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	29	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	30	.\" SUCH DAMAGE.
	31	.\"
224c7076 A	32	.\" @(#)usleep.3 8.1 (Berkeley) 6/4/93
224c7076 A	33	.\" $FreeBSD: src/lib/libc/gen/usleep.3,v 1.18 2002/12/29 00:59:09 mike Exp $
e9ce8d39	34	.\"
224c7076 A	35	.Dd February 13, 1998
224c7076 A	36	.Dt USLEEP 3
e9ce8d39 A	37	.Os
e9ce8d39 A	38	.Sh NAME
224c7076 A	39	.Nm usleep
224c7076 A	40	.Nd suspend thread execution for an interval measured in microseconds
e9ce8d39 A	41	.Sh LIBRARY
	42	.Lb libc
	43	.Sh SYNOPSIS
5b2abdfb	44	.In unistd.h
e9ce8d39	45	.Ft int
224c7076 A	46	.Fo usleep
	47	.Fa "useconds_t useconds"
	48	.Fc
e9ce8d39 A	49	.Sh DESCRIPTION
e9ce8d39 A	50	The
224c7076 A	51	.Fn usleep
	52	function suspends execution of the calling thread until either
	53	.Fa useconds
	54	microseconds have elapsed
	55	or a signal is delivered to the thread whose action
	56	is to invoke a signal-catching function
	57	or to terminate the thread or process.
	58	The actual time slept may be longer, due to system latencies
	59	and possible limitations in the timer resolution of the hardware.
	60	.Pp
	61	This function is implemented, using
	62	.Xr nanosleep 2 ,
	63	by pausing for
	64	.Fa useconds
	65	microseconds or until a signal occurs.
	66	Consequently, in this implementation,
	67	sleeping has no effect on the state of process timers
	68	and there is no special handling for SIGALRM.
e9ce8d39	69	.Sh RETURN VALUES
224c7076 A	70	.Rv -std usleep
224c7076 A	71	.Sh ERRORS
5b2abdfb	72	The
224c7076	73	.Fn usleep
5b2abdfb	74	function
224c7076 A	75	will fail if:
	76	.Bl -tag -width Er
	77	.It Bq Er EINTR
	78	A signal was delivered to the process and its
	79	action was to invoke a signal-catching function.
	80	.El
e9ce8d39	81	.Sh SEE ALSO
224c7076 A	82	.Xr nanosleep 2 ,
224c7076 A	83	.Xr sleep 3
e9ce8d39 A	84	.Sh HISTORY
e9ce8d39 A	85	The
224c7076	86	.Fn usleep
5b2abdfb	87	function appeared in
224c7076	88	.Bx 4.3 .