gen/ualarm.3

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  32 .\"     From: @(#)ualarm.3      8.2 (Berkeley) 4/19/94
  33 .\" $FreeBSD: src/lib/libc/gen/ualarm.3,v 1.19 2004/07/02 23:52:10 ru Exp $
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  35 .Dd April 19, 1994
  36 .Dt UALARM 3
  37 .Os
  38 .Sh NAME
  39 .Nm ualarm
  40 .Nd schedule signal after specified time
  41 .Sh LIBRARY
  42 .Lb libc
  43 .Sh SYNOPSIS
  44 .In unistd.h
  45 .Ft useconds_t
  46 .Fo ualarm
  47 .Fa "useconds_t useconds"
  48 .Fa "useconds_t interval"
  49 .Fc
  50 .Sh DESCRIPTION
  51 .Bf -symbolic
  52 This is a simplified interface to
  53 .Xr setitimer 2 .
  54 .Ef
  55 .Pp
  56 The
  57 .Fn ualarm
  58 function
  59 waits a count of
  60 .Fa useconds
  61 before asserting the terminating signal
  62 .Dv SIGALRM .
  63 System activity or time used in processing the call may cause a slight
  64 delay.
  65 .Pp
  66 If the
  67 .Fa interval
  68 argument is non-zero, the
  69 .Dv SIGALRM
  70 signal will be sent
  71 to the process every
  72 .Fa interval
  73 microseconds after the timer expires (e.g., after
  74 .Fa useconds
  75 number of microseconds have passed).
  76 .Pp
  77 Due to a
  78 .Xr setitimer 2
  79 restriction, the maximum number of
  80 .Fa useconds
  81 and
  82 .Fa interval
  83 is limited to 100,000,000,000,000
  84 (in case this value fits in the unsigned integer).
  85 .Sh RETURN VALUES
  86 When the signal has successfully been caught,
  87 .Fn ualarm
  88 returns the amount of time left on the clock.
  89 .Sh NOTES
  90 A microsecond is 0.000001 seconds.
  91 .Sh SEE ALSO
  92 .Xr getitimer 2 ,
  93 .Xr setitimer 2 ,
  94 .Xr sigpause 2 ,
  95 .Xr sigvec 2 ,
  96 .Xr alarm 3 ,
  97 .Xr signal 3 ,
  98 .Xr sleep 3 ,
  99 .Xr usleep 3
 100 .Sh HISTORY
 101 The
 102 .Fn ualarm
 103 function appeared in
 104 .Bx 4.3 .