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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 non-zero, 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(3),
       timer_delete(3),         timer_getoverrun(3),         timer_gettime(3),
       timer_settime(3), usleep(3) is unspecified.

       This  function  is obsolete.  Use setitimer(2) or POSIX interval timers
       (timer_create(3), 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 3.15 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)