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 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
       original Standard can be obtained online at http://www.opengroup.org/unix/online.html .