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.\" 3. 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.\" 30.Dd April 19, 1994 31.Dt UALARM 3 32.Os 33.Sh NAME 34.Nm ualarm 35.Nd schedule signal after specified time 36.Sh LIBRARY 37.Lb libc 38.Sh SYNOPSIS 39.In unistd.h 40.Ft useconds_t 41.Fn ualarm "useconds_t microseconds" "useconds_t interval" 42.Sh DESCRIPTION 43.Bf -symbolic 44This is a simplified interface to 45.Xr setitimer 2 . 46.Ef 47.Pp 48The 49.Fn ualarm 50function 51waits a count of 52.Fa microseconds 53before asserting the terminating signal 54.Dv SIGALRM . 55System activity or time used in processing the call may cause a slight 56delay. 57.Pp 58If the 59.Fa interval 60argument is non-zero, the 61.Dv SIGALRM 62signal will be sent 63to the process every 64.Fa interval 65microseconds after the timer expires (e.g.\& after 66.Fa microseconds 67number of microseconds have passed). 68.Pp 69Due to 70.Xr setitimer 2 71restriction the maximum number of 72.Fa microseconds 73and 74.Fa interval 75is limited to 100000000000000 76(in case this value fits in the unsigned integer). 77.Sh RETURN VALUES 78When the signal has successfully been caught, 79.Fn ualarm 80returns the amount of time left on the clock. 81.Sh NOTES 82A microsecond is 0.000001 seconds. 83.Sh SEE ALSO 84.Xr getitimer 2 , 85.Xr setitimer 2 , 86.Xr sigaction 2 , 87.Xr sigsuspend 2 , 88.Xr alarm 3 , 89.Xr signal 3 , 90.Xr sleep 3 , 91.Xr usleep 3 92.Sh HISTORY 93The 94.Fn ualarm 95function appeared in 96.Bx 4.3 . 97