UALARM(P)                                                                               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 pro-
       cess 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 sig-
       nal, SIGALRM, is not caught or ignored, the calling process is terminated.

       Implementations  may place limitations on the granularity of timer values. For each inter-
       val timer, if the requested timer value requires a finer granularity than the  implementa-
       tion 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 Technology -- 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 orig-
       inal Standard can be obtained online at http://www.opengroup.org/unix/online.html .



POSIX                                          2003                                     UALARM(P)