ualarm(3) [posix man page]

UALARM(P)						     POSIX Programmer's Manual							 UALARM(P)

NAME

       ualarm - set the interval timer

SYNOPSIS

       #include <unistd.h>

       useconds_t ualarm(useconds_t useconds, useconds_t interval);

DESCRIPTION

       The  ualarm()  function	shall  cause  the SIGALRM signal to be generated for the calling process after the number of realtime microseconds
       specified by the useconds argument has elapsed.	When the interval argument is non-zero, repeated timeout notification occurs with a period
       in  microseconds  specified by the interval argument. If the notification signal, SIGALRM, is not caught or ignored, the calling process is
       terminated.

       Implementations may place limitations on the granularity of timer values. For each interval timer, if the requested timer value requires  a
       finer granularity than the implementation supports, the actual timer value shall be rounded up to the next supported value.

       Interactions between ualarm() and any of the following are unspecified:

	      alarm()
	      nanosleep()
	      setitimer()
	      timer_create()
	      timer_delete()
	      timer_getoverrun()
	      timer_gettime()
	      timer_settime()
	      sleep()

RETURN VALUE

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

ERRORS

       No errors are defined.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

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

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       alarm()	,  nanosleep()	,  setitimer()	,  sleep() , timer_create() , timer_delete() , timer_getoverrun() , the Base Definitions volume of
       IEEE Std 1003.1-2001, <unistd.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
       ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
       Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and  the  original  IEEE
       and  The  Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained
       online at http://www.opengroup.org/unix/online.html .

IEEE
/The Open Group						       2003								 UALARM(P)

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UALARM(3)						     Linux Programmer's Manual							 UALARM(3)

NAME

       ualarm - schedule signal after given number of microseconds

SYNOPSIS

       #include <unistd.h>

       useconds_t ualarm(useconds_t usecs, useconds_t interval);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       ualarm(): _BSD_SOURCE || _XOPEN_SOURCE >= 500

DESCRIPTION

       The ualarm() function causes the signal SIGALRM to be sent to the invoking process after (not less than) usecs microseconds.  The delay may
       be lengthened slightly by any system activity or by the time spent processing the call or by the granularity of system timers.

       Unless caught or ignored, the SIGALRM signal will terminate the process.

       If the interval argument is nonzero, further SIGALRM signals will be sent every interval microseconds after the first.

RETURN VALUE

       This function returns the number of microseconds remaining for any alarm that was previously set, or 0 if no alarm was pending.

ERRORS

       EINTR  Interrupted by a signal.

       EINVAL usecs or interval is not smaller than 1000000.  (On systems where that is considered an error.)

CONFORMING TO

       4.3BSD, POSIX.1-2001.  POSIX.1-2001 marks ualarm() as obsolete.	POSIX.1-2008 removes the specification of ualarm().   4.3BSD,  SUSv2,  and
       POSIX do not define any errors.

NOTES

       The  type useconds_t is an unsigned integer type capable of holding integers in the range [0,1000000].  On the original BSD implementation,
       and in glibc before version 2.1, the arguments to ualarm() were instead typed as unsigned int.  Programs will  be  more	portable  if  they
       never mention useconds_t explicitly.

       The  interaction  of  this  function  with  other  timer functions such as alarm(2), sleep(3), nanosleep(2), setitimer(2), timer_create(2),
       timer_delete(2), timer_getoverrun(2), timer_gettime(2), timer_settime(2), usleep(3) is unspecified.

       This function is obsolete.  Use setitimer(2) or POSIX interval timers (timer_create(2), etc.)  instead.

SEE ALSO

       alarm(2), getitimer(2), nanosleep(2), select(2), setitimer(2), usleep(3), time(7)

COLOPHON

       This page is part of release 3.25 of the Linux man-pages project.  A description of the project, and information about reporting bugs,  can
       be found at http://www.kernel.org/doc/man-pages/.

								    2008-08-06								 UALARM(3)

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ualarm(3) [posix man page]

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