• 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(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  This function is obsolete.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
  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 3.19 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/.
  

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