gen/FreeBSD/ualarm.3

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  28 .\"     From: @(#)ualarm.3      8.2 (Berkeley) 4/19/94
  29 .\" $FreeBSD: src/lib/libc/gen/ualarm.3,v 1.20 2007/01/09 00:27:56 imp Exp $
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  31 .Dd April 19, 1994
  32 .Dt UALARM 3
  33 .Os
  34 .Sh NAME
  35 .Nm ualarm
  36 .Nd schedule signal after specified time
  37 .Sh LIBRARY
  38 .Lb libc
  39 .Sh SYNOPSIS
  40 .In unistd.h
  41 .Ft useconds_t
  42 .Fo ualarm
  43 .Fa "useconds_t useconds"
  44 .Fa "useconds_t interval"
  45 .Fc
  46 .Sh DESCRIPTION
  47 .Bf -symbolic
  48 This is a simplified interface to
  49 .Xr setitimer 2 .
  50 .Ef
  51 .Pp
  52 The
  53 .Fn ualarm
  54 function
  55 waits a count of
  56 .Fa useconds
  57 before asserting the terminating signal
  58 .Dv SIGALRM .
  59 System activity or time used in processing the call may cause a slight
  60 delay.
  61 .Pp
  62 If the
  63 .Fa interval
  64 argument is non-zero, the
  65 .Dv SIGALRM
  66 signal will be sent
  67 to the process every
  68 .Fa interval
  69 microseconds after the timer expires (e.g., after
  70 .Fa useconds
  71 number of microseconds have passed).
  72 .Pp
  73 Due to a
  74 .Xr setitimer 2
  75 restriction, the maximum number of
  76 .Fa useconds
  77 and
  78 .Fa interval
  79 is limited to 100,000,000,000,000
  80 (in case this value fits in the unsigned integer).
  81 .Sh RETURN VALUES
  82 When the signal has successfully been caught,
  83 .Fn ualarm
  84 returns the amount of time left on the clock.
  85 .Sh NOTES
  86 A microsecond is 0.000001 seconds.
  87 .Sh SEE ALSO
  88 .Xr getitimer 2 ,
  89 .Xr setitimer 2 ,
  90 .Xr sigpause 2 ,
  91 .Xr sigvec 2 ,
  92 .Xr alarm 3 ,
  93 .Xr signal 3 ,
  94 .Xr sleep 3 ,
  95 .Xr usleep 3
  96 .Sh HISTORY
  97 The
  98 .Fn ualarm
  99 function appeared in
 100 .Bx 4.3 .