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98 lines
2.9 KiB
Groff
98 lines
2.9 KiB
Groff
.\" Copyright (c) 1986, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" From: @(#)ualarm.3 8.2 (Berkeley) 4/19/94
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.\" $FreeBSD$
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.\"
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.Dd April 19, 1994
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.Dt UALARM 3
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.Os
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.Sh NAME
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.Nm ualarm
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.Nd schedule signal after specified time
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In unistd.h
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.Ft useconds_t
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.Fn ualarm "useconds_t microseconds" "useconds_t interval"
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.Sh DESCRIPTION
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.Bf -symbolic
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This is a simplified interface to
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.Xr setitimer 2 .
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.Ef
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.Pp
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The
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.Fn ualarm
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function
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waits a count of
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.Fa microseconds
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before asserting the terminating signal
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.Dv SIGALRM .
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System activity or time used in processing the call may cause a slight
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delay.
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.Pp
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If the
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.Fa interval
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argument is non-zero, the
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.Dv SIGALRM
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signal will be sent
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to the process every
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.Fa interval
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microseconds after the timer expires (e.g.\& after
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.Fa microseconds
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number of microseconds have passed).
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.Pp
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Due to
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.Xr setitimer 2
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restriction the maximum number of
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.Fa microseconds
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and
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.Fa interval
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is limited to 100000000000000
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(in case this value fits in the unsigned integer).
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.Sh RETURN VALUES
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When the signal has successfully been caught,
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.Fn ualarm
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returns the amount of time left on the clock.
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.Sh NOTES
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A microsecond is 0.000001 seconds.
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.Sh SEE ALSO
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.Xr getitimer 2 ,
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.Xr setitimer 2 ,
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.Xr sigpause 2 ,
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.Xr sigvec 2 ,
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.Xr alarm 3 ,
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.Xr signal 3 ,
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.Xr sleep 3 ,
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.Xr usleep 3
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.Sh HISTORY
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The
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.Fn ualarm
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function appeared in
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.Bx 4.3 .
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