ualarm(2) System Calls Manual ualarm(2)NAME
ualarm - set the interval timer
SYNOPSIS DESCRIPTION
The function causes the signal to be generated for the calling process after the number of real-time 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, 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 will be rounded up to the next supported value.
Interactions between and either or are unspecified.
RETURN VALUE
The function returns the number of microseconds remaining from the previous call. If no timeouts are pending or if has not previously been
called, returns 0.
ERRORS
No errors are defined.
APPLICATION USAGE
The function is a simplified interface to and uses the interval timer.
SEE ALSO alarm(2), getitimer(2), sleep(3C), <unistd.h>.
CHANGE HISTORY
First released in Issue 4, Version 2.
ualarm(2)
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UALARM(P) POSIX Programmer's Manual 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 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 Technol-
ogy -- 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 .
IEEE /The Open Group 2003 UALARM(P)