IBM Version 4 manual Signal, Action

Ÿ Terminal (work station) activity

ŸCalling an API such as thekill()X/Openfu ction, the American National

Standard C raise() function, or theCEESGL ILE (signal a condition) function.

The signal		action		vector	is a list	of signal-handling actions for each define
The	signal		action		vector is maintained separately for each process and
from	the		parent		process. The signal action vector specifies the signal-h
actions		for		both	synchronously	and asynchronously generated signals.

A signal is saiddeliveredto be to a process when the specified signal-handling action for the signal is taken.

The following describes some of	the support provided		by OS/400	signal m
ment. The set of defined signals	is determined	by the system. The sy
fies the attributes for each	defined signal.	These	attributes	consist

number, the initial signal action, and the signal default action. The sys specifies an initial signal blocking mask. The set of defined signals, th butes, and signal blocking mask are referredsignal controls to . as

A signal can be generated or delivered only to a process that has e interest in signals. An error condition results under the following conditi

Ÿ An	attempt	is made to generate a signal when the system signal cont
not	been	initialized.

ŸAn attempt is made to generate a signal for a process that has no

enabled for signals.

A process can express an interest		in signalsQp0 EnableSignals()by calling the
API. In addition, calling particular		signal		APIs	implicitly enables			the pr
signals.
If the	process has not been enabled		for signals,			the	process	signal
from signal controls established by		the	system		during IPL		(the	system
trols). An error condition results if		an attempt is made to enable signa
process	before the system signal	controls		have	been	initialized.

Once the process signal controls have been initialized, the user is pe change the signal controls for the process.

The	attributes		for	each defined signal		are storedsignal in			an	object calle
monitor	. The	system		supports a maximum	of	63	signal	monitors		for each	pr
The	process signal action vector is a				list		of signal monitors, one for
signal. The		signal	monitor contains, but		is	not	limited	to,	the following		i

ŸSignal action

Ÿ Signal default action

ŸSignal options

The signal action defines the action to be taken by the system when a receives an unblocked signal. The user can change the signal action for signal monitor.

The signal	default	action	field defines		the action to be taken by the sy
the signal action ishandlset usingto				signal default. Theactionsignal default
action for a signal monitor is				set	in the system signal controls and ca
changed	for	a process signal		monitor.

8-24System API Programming V4R1