1UALARM(3P)                 POSIX Programmer's Manual                UALARM(3P)
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PROLOG

6       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
7       implementation of this interface may differ (consult the  corresponding
8       Linux  manual page for details of Linux behavior), or the interface may
9       not be implemented on Linux.
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NAME

12       ualarm - set the interval timer
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SYNOPSIS

15       #include <unistd.h>
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17       useconds_t ualarm(useconds_t useconds, useconds_t interval);
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DESCRIPTION

21       The ualarm() function shall cause the SIGALRM signal  to  be  generated
22       for the calling process after the number of realtime microseconds spec‐
23       ified by the useconds argument has elapsed.  When the interval argument
24       is  non-zero,  repeated  timeout  notification  occurs with a period in
25       microseconds specified by the interval argument.  If  the  notification
26       signal,  SIGALRM, is not caught or ignored, the calling process is ter‐
27       minated.
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29       Implementations may place limitations on the granularity of timer  val‐
30       ues.  For  each interval timer, if the requested timer value requires a
31       finer granularity than the implementation supports,  the  actual  timer
32       value shall be rounded up to the next supported value.
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34       Interactions between ualarm() and any of the following are unspecified:
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37              alarm()
38              nanosleep()
39              setitimer()
40              timer_create()
41              timer_delete()
42              timer_getoverrun()
43              timer_gettime()
44              timer_settime()
45              sleep()
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RETURN VALUE

48       The ualarm() function shall return the number of microseconds remaining
49       from the previous ualarm() call. If  no  timeouts  are  pending  or  if
50       ualarm() has not previously been called, ualarm() shall return 0.
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ERRORS

53       No errors are defined.
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55       The following sections are informative.
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EXAMPLES

58       None.
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APPLICATION USAGE

61       Applications are recommended to use nanosleep() if the Timers option is
62       supported,    or    setitimer(),    timer_create(),     timer_delete(),
63       timer_getoverrun(), timer_gettime(), or timer_settime() instead of this
64       function.
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RATIONALE

67       None.
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FUTURE DIRECTIONS

70       None.
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SEE ALSO

73       alarm(),    nanosleep(),    setitimer(),    sleep(),    timer_create(),
74       timer_delete(),  timer_getoverrun(),  the  Base  Definitions  volume of
75       IEEE Std 1003.1-2001, <unistd.h>
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78       Portions of this text are reprinted and reproduced in  electronic  form
79       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
80       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
81       Specifications  Issue  6,  Copyright  (C) 2001-2003 by the Institute of
82       Electrical and Electronics Engineers, Inc and The Open  Group.  In  the
83       event of any discrepancy between this version and the original IEEE and
84       The Open Group Standard, the original IEEE and The Open Group  Standard
85       is  the  referee document. The original Standard can be obtained online
86       at http://www.opengroup.org/unix/online.html .
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90IEEE/The Open Group                  2003                           UALARM(3P)
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