1.\" Copyright (c) 1980, 1991, 1993, 1994 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.Dd April 2, 2022 29.Dt ALARM 3 30.Os 31.Sh NAME 32.Nm alarm 33.Nd set signal timer alarm 34.Sh LIBRARY 35.Lb libc 36.Sh SYNOPSIS 37.In unistd.h 38.Ft unsigned int 39.Fn alarm "unsigned int seconds" 40.Sh DESCRIPTION 41.Bf -symbolic 42This interface is made obsolete by 43.Xr setitimer 2 . 44.Ef 45.Pp 46The 47.Fn alarm 48function sets a timer to deliver the signal 49.Dv SIGALRM 50to the calling process after the specified number of 51.Fa seconds . 52If an alarm has already been set with 53.Fn alarm 54but has not been delivered, another call to 55.Fn alarm 56will supersede the prior call. 57The request 58.Fn alarm "0" 59voids the current 60alarm and the signal SIGALRM will not be delivered. 61.Pp 62Due to 63.Xr setitimer 2 64restriction the maximum number of 65.Fa seconds 66allowed is 100000000. 67.Sh RETURN VALUES 68The return value of 69.Fn alarm 70is the amount of time left on the timer from a previous call to 71.Fn alarm . 72If no alarm is currently set, the return value is 0. 73.Sh SEE ALSO 74.Xr setitimer 2 , 75.Xr sigaction 2 , 76.Xr sigsuspend 2 , 77.Xr signal 3 , 78.Xr sleep 3 , 79.Xr ualarm 3 , 80.Xr usleep 3 81.\" .Sh STANDARDS 82.\" The 83.\" .Fn alarm 84.\" function conforms to 85.\" .St -p1003.1-90 . 86.Sh HISTORY 87An 88.Fn alarm 89system call appeared in the Programmer's Workbench (PWB/UNIX) 90and was ported to 91.At v7 . 92For 93.Bx 4.1c , 94it was reimplemented as a wrapper around the 95.Xr setitimer 2 96system call. 97