alarm.2

Unix操作系统minix 2.0源码

.\" Copyright (c) 1980 Regents of the University of California.
.\" All rights reserved.  The Berkeley software License Agreement
.\" specifies the terms and conditions for redistribution.
.\"
.\"	@(#)alarm.3c	6.3 (Berkeley) 5/27/86
.\"
.TH ALARM 2  "May 27, 1986"
.UC 4
.SH NAME
alarm \- schedule signal after specified time
.SH SYNOPSIS
.nf
.ft B
#include <unistd.h>

unsigned int alarm(unsigned int \fIseconds\fP)
.ft R
.fi
.SH DESCRIPTION
.B Alarm
causes signal SIGALRM, see
.BR sigaction (2),
to be sent to the invoking process
in a number of seconds given by the argument.
Unless caught or ignored, the signal terminates the process.
.PP
Alarm requests are not stacked; successive calls reset the alarm clock.
If the argument is 0, any alarm request is canceled.
Because of scheduling delays,
resumption of execution of when the signal is
caught may be delayed an arbitrary amount.
.PP
The return value is the amount of time previously remaining in the alarm clock.
.SH "SEE ALSO"
.BR pause (2),
.BR sigsuspend (2),
.BR sigaction (2),
.BR sleep (3).