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 microsec-
       onds.  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.   Pro-
       grams 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       This function is obsolete.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)