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.\"     @(#)alarm.3	8.2 (Berkeley) 4/19/94
.\"
.Dd April 19, 1994
.Dt ALARM 3
.Os
.Sh NAME
.Nm alarm
.Nd set signal timer alarm
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.Fd #include \*[Lt]unistd.h\*[Gt]
.Ft unsigned int
.Fn alarm "unsigned int seconds"
.Sh DESCRIPTION
.Bf -symbolic
This interface is made obsolete by
.Xr setitimer 2 .
.Ef
.Pp
The
.Fn alarm
function sets a timer to deliver the signal
.Dv SIGALRM
to the calling proccess
.Ar seconds
after the call to
.Fn alarm .
If an alarm has already been set with
.Fn alarm
but has not been delivered, another call to
.Fn alarm
will supersede the prior call.
The request
.Fn alarm "0"
voids the current
alarm and the signal SIGALRM will not be delivered. The maximum number of
.Ar seconds
allowed
is 2147483647.
.Pp
The return value of
.Fn alarm
is the amount of time left on the timer from a previous call to
.Fn alarm .
If no alarm is currently set, the return value is 0.
If there is an error setting the timer,
.Fn alarm
returns ((unsigned int) -1).
.Sh SEE ALSO
.Xr setitimer 2 ,
.Xr sigaction 2 ,
.Xr sigsuspend 2 ,
.Xr signal 3 ,
.Xr sigvec 3 ,
.Xr sleep 3 ,
.Xr ualarm 3 ,
.Xr usleep 3
.Sh STANDARDS
The
.Fn alarm
function conforms to
.St -p1003.1-90 .
.Sh HISTORY
An
.Fn alarm
function appeared in
.At v7 .