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.\" 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.
.\" 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
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.\"
.\" From: @(#)ualarm.3 8.2 (Berkeley) 4/19/94
.\" $FreeBSD$
.\"
.Dd April 19, 1994
.Dt UALARM 3
.Os
.Sh NAME
.Nm ualarm
.Nd schedule signal after specified time
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In unistd.h
.Ft useconds_t
.Fn ualarm "useconds_t microseconds" "useconds_t interval"
.Sh DESCRIPTION
.Bf -symbolic
This is a simplified interface to
.Xr setitimer 2 .
.Ef
.Pp
The
.Fn ualarm
function
waits a count of
.Fa microseconds
before asserting the terminating signal
.Dv SIGALRM .
System activity or time used in processing the call may cause a slight
delay.
.Pp
If the
.Fa interval
argument is non-zero, the
.Dv SIGALRM
signal will be sent
to the process every
.Fa interval
microseconds after the timer expires (e.g.\& after
.Fa microseconds
number of microseconds have passed).
.Pp
Due to
.Xr setitimer 2
restriction the maximum number of
.Fa microseconds
and
.Fa interval
is limited to 100000000000000
(in case this value fits in the unsigned integer).
.Sh RETURN VALUES
When the signal has successfully been caught,
.Fn ualarm
returns the amount of time left on the clock.
.Sh NOTES
A microsecond is 0.000001 seconds.
.Sh SEE ALSO
.Xr getitimer 2 ,
.Xr setitimer 2 ,
.Xr sigpause 2 ,
.Xr sigvec 2 ,
.Xr alarm 3 ,
.Xr signal 3 ,
.Xr sleep 3 ,
.Xr usleep 3
.Sh HISTORY
The
.Fn ualarm
function appeared in
.Bx 4.3 .
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