gen/FreeBSD/alarm.3

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  28 .\"     @(#)alarm.3     8.2 (Berkeley) 4/19/94
  29 .\" $FreeBSD: src/lib/libc/gen/alarm.3,v 1.17 2007/01/09 00:27:52 imp Exp $
  30 .\"
  31 .Dd April 19, 1994
  32 .Dt ALARM 3
  33 .Os
  34 .Sh NAME
  35 .Nm alarm
  36 .Nd set signal timer alarm
  37 .Sh LIBRARY
  38 .Lb libc
  39 .Sh SYNOPSIS
  40 .In unistd.h
  41 .Ft unsigned
  42 .Fn alarm "unsigned seconds"
  43 .Sh DESCRIPTION
  44 .Bf -symbolic
  45 This interface is made obsolete by
  46 .Xr setitimer 2 .
  47 .Ef
  48 .Pp
  49 The
  50 .Fn alarm
  51 function sets a timer to deliver the signal
  52 .Dv SIGALRM
  53 to the calling process after the specified number of
  54 .Fa seconds .
  55 If an alarm has already been set with
  56 .Fn alarm
  57 but has not been delivered, another call to
  58 .Fn alarm
  59 will supersede the prior call.
  60 The request
  61 .Fn alarm "0"
  62 voids the current
  63 alarm and the signal SIGALRM will not be delivered.
  64 .Pp
  65 Due to
  66 .Xr setitimer 2
  67 restriction the maximum number of
  68 .Fa seconds
  69 allowed is 100000000.
  70 .Sh RETURN VALUES
  71 The return value of
  72 .Fn alarm
  73 is the amount of time left on the timer from a previous call to
  74 .Fn alarm .
  75 If no alarm is currently set, the return value is 0.
  76 .Sh SEE ALSO
  77 .Xr setitimer 2 ,
  78 .Xr sigaction 2 ,
  79 .Xr sigpause 2 ,
  80 .Xr sigvec 2 ,
  81 .Xr signal 3 ,
  82 .Xr sleep 3 ,
  83 .Xr ualarm 3 ,
  84 .Xr usleep 3
  85 .\" .Sh STANDARDS
  86 .\" The
  87 .\" .Fn alarm
  88 .\" function conforms to
  89 .\" .St -p1003.1-90 .
  90 .Sh HISTORY
  91 An
  92 .Fn alarm
  93 function appeared in
  94 .At v7 .