Availability:built-in
prolog_alert_signal(?Old,
+New)Query or set the signal used to unblock blocking system calls on
Unix(-like) systems and process pending Prolog signals. The default is
SIGUSR2. See also --sigalert. New
can be a signal name or number. See on_signal/3
for how the Prolog signal name is defined. The Old argument
is unified to the signal name if known and the number otherwise. Notably
the value 0 (zero) indicates that the system does not use an alarm
signal. On POSIX systems, this implies that system calls are not
interrupted by
thread_signal/2.
This predicate is only defined on systems where the alert signal
mechanism is used.
