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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 n unistd.h .Ft unsigned int .Fn alarm "unsigned int seconds" .Sh DESCRIPTION f -symbolic This interface is made obsolete by .Xr setitimer 2 . .Ef
p The .Fn alarm function sets a timer to deliver the signal .Dv SIGALRM to the calling process .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.
p 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 .