gen/alarm.3

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  32 .\"     @(#)alarm.3     8.2 (Berkeley) 4/19/94
  33 .\" $FreeBSD: src/lib/libc/gen/alarm.3,v 1.15 2001/10/01 16:08:50 ru Exp $
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  35 .Dd April 19, 1994
  36 .Dt ALARM 3
  37 .Os
  38 .Sh NAME
  39 .Nm alarm
  40 .Nd set signal timer alarm
  41 .Sh LIBRARY
  42 .Lb libc
  43 .Sh SYNOPSIS
  44 .In unistd.h
  45 .Ft unsigned int
  46 .Fn alarm "unsigned int seconds"
  47 .Sh DESCRIPTION
  48 .Bf -symbolic
  49 This interface is made obsolete by
  50 .Xr setitimer 2 .
  51 .Ef
  52 .Pp
  53 The
  54 .Fn alarm
  55 function sets a timer to deliver the signal
  56 .Dv SIGALRM
  57 to the calling process after the specified number of
  58 .Fa seconds .
  59 If an alarm has already been set with
  60 .Fn alarm
  61 but has not been delivered, another call to
  62 .Fn alarm
  63 will supersede the prior call.
  64 The request
  65 .Fn alarm "0"
  66 voids the current
  67 alarm and the signal SIGALRM will not be delivered.
  68 .Pp
  69 Due to
  70 .Xr setitimer 2
  71 restriction the maximum number of
  72 .Ar seconds
  73 allowed is 100000000.
  74 .Sh RETURN VALUES
  75 The return value of
  76 .Fn alarm
  77 is the amount of time left on the timer from a previous call to
  78 .Fn alarm .
  79 If no alarm is currently set, the return value is 0.
  80 .Sh SEE ALSO
  81 .Xr setitimer 2 ,
  82 .Xr sigaction 2 ,
  83 .Xr sigpause 2 ,
  84 .Xr sigvec 2 ,
  85 .Xr signal 3 ,
  86 .Xr sleep 3 ,
  87 .Xr ualarm 3 ,
  88 .Xr usleep 3
  89 .\" .Sh STANDARDS
  90 .\" The
  91 .\" .Fn alarm
  92 .\" function conforms to
  93 .\" .St -p1003.1-90 .
  94 .Sh HISTORY
  95 An
  96 .Fn alarm
  97 function appeared in
  98 .At v7 .