4.2BSD/usr/man/man3/alarm.3c

.TH ALARM 3C  "18 July 1983"
.SH NAME
alarm \- schedule signal after specified time
.SH SYNOPSIS
.nf
.B alarm(seconds)
.B unsigned seconds;
.fi
.SH DESCRIPTION
.ft B
This interface is obsoleted by setitimer(2).
.ft R
.PP
.I Alarm
causes signal SIGALRM, see
.IR signal (3C),
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.
The longest specifiable delay time is 2147483647 seconds.
.PP
The return value is the amount of time previously remaining in the alarm clock.
.SH "SEE ALSO"
sigpause(2), sigvec(2), signal(3C), sleep(3)