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	1	.\" Copyright (c) 1986, 1991, 1993
	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	.\" 4. Neither the name of the University nor the names of its contributors
	13	.\" may be used to endorse or promote products derived from this software
	14	.\" without specific prior written permission.
	15	.\"
	16	.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	17	.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	18	.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	19	.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	20	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	21	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	22	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	23	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	24	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	25	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	26	.\" SUCH DAMAGE.
	27	.\"
	28	.\" From: @(#)ualarm.3 8.2 (Berkeley) 4/19/94
	29	.\" $FreeBSD: src/lib/libc/gen/ualarm.3,v 1.20 2007/01/09 00:27:56 imp Exp $
	30	.\"
	31	.Dd April 19, 1994
	32	.Dt UALARM 3
	33	.Os
	34	.Sh NAME
	35	.Nm ualarm
	36	.Nd schedule signal after specified time
	37	.Sh LIBRARY
	38	.Lb libc
	39	.Sh SYNOPSIS
	40	.In unistd.h
	41	.Ft useconds_t
	42	.Fo ualarm
	43	.Fa "useconds_t useconds"
	44	.Fa "useconds_t interval"
	45	.Fc
	46	.Sh DESCRIPTION
	47	.Bf -symbolic
	48	This is a simplified interface to
	49	.Xr setitimer 2 .
	50	.Ef
	51	.Pp
	52	The
	53	.Fn ualarm
	54	function
	55	waits a count of
	56	.Fa useconds
	57	before asserting the terminating signal
	58	.Dv SIGALRM .
	59	System activity or time used in processing the call may cause a slight
	60	delay.
	61	.Pp
	62	If the
	63	.Fa interval
	64	argument is non-zero, the
	65	.Dv SIGALRM
	66	signal will be sent
	67	to the process every
	68	.Fa interval
	69	microseconds after the timer expires (e.g., after
	70	.Fa useconds
	71	number of microseconds have passed).
	72	.Pp
	73	Due to a
	74	.Xr setitimer 2
	75	restriction, the maximum number of
	76	.Fa useconds
	77	and
	78	.Fa interval
	79	is limited to 100,000,000,000,000
	80	(in case this value fits in the unsigned integer).
	81	.Sh RETURN VALUES
	82	When the signal has successfully been caught,
	83	.Fn ualarm
	84	returns the amount of time left on the clock.
	85	.Sh NOTES
	86	A microsecond is 0.000001 seconds.
	87	.Sh SEE ALSO
	88	.Xr getitimer 2 ,
	89	.Xr setitimer 2 ,
	90	.Xr sigpause 2 ,
	91	.Xr sigvec 2 ,
	92	.Xr alarm 3 ,
	93	.Xr signal 3 ,
	94	.Xr sleep 3 ,
	95	.Xr usleep 3
	96	.Sh HISTORY
	97	The
	98	.Fn ualarm
	99	function appeared in
	100	.Bx 4.3 .