NAME

ualarm — schedule signal after interval in microseconds

SYNOPSIS

#include <unistd.h>

useconds_t
ualarm(useconds_t useconds, useconds_t interval);

DESCRIPTION

The ualarm() function causes the SIGALRM 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, SIGALRM, is not caught or ignored, the calling process is terminated.

Because of scheduling delays, resumption of execution when the signal is caught may be delayed an arbitrary amount of time.

Interactions between ualarm() and either alarm(2) or sleep(3C) are unspecified.

RETURN VALUES

The ualarm() function returns the number of microseconds remaining from the previous ualarm() call. If no timeouts are pending or if ualarm() has not previously been called, ualarm() returns 0.

ERRORS

No errors are defined.

USAGE

The ualarm() function is a simplified interface to setitimer(2), and uses the ITIMER_REAL interval timer. It's use has been deprecated in favor of the timer_create(3C) family of functions.

INTERFACE STABILITY

Obsolete Standard.

SEE ALSO

alarm(2), setitimer(2), sighold(3C), signal(3C), sleep(3C), timer_create(3C), usleep(3C), unistd.h(3HEAD), standards(7)

STANDARDS

The ualarm() function is available in the following compilation environments. See standards(7).

• X/Open Portability Guide Issue 4, Version 2 (“XPG4.2”)
• Version 2 of the Single UNIX Specification (“SUSv2”)
• Version 3 of the Single UNIX Specification (“SUSv3”)

It is marked obsolete in Version 3 of the Single UNIX Specification (“SUSv3”), and was removed from IEEE Std 1003.1-2008 (“POSIX.1”).