[unix-history] / man / man2 / signal.2

.th SIGNAL II 8/5/73
.sh NAME
signal \*- catch or ignore signals
.sh SYNOPSIS
(signal = 48.)
.br
.ft B
sys  signal; sig; value
.s3
signal(sig, func)
.br
int (*func)();
.ft R
.sh DESCRIPTION
When the signal
defined by
.it sig
is sent to the current process,
it is to be treated according to
.it value.
The following is the list of signals:
.s3
.lp +10 5
1	hangup
.lp +10 5
2	interrupt
.lp +10 5
3*	quit
.lp +10 5
4*	illegal instruction
.lp +10 5
5*	trace trap
.lp +10 5
6*	IOT instruction
.lp +10 5
7*	EMT instruction
.lp +10 5
8*	floating point exception
.lp +10 5
9	kill (cannot be caught or ignored)
.lp +10 5
10*	bus error
.lp +10 5
11*	segmentation violation
.lp +10 5
12*	bad argument to sys call
.s3
.i0
If
.it value
is 0, the default system
action applies to the signal.
This is processes termination
with or without a core dump.
If
.it value
is odd, the signal is ignored.
Any other even
.it value
specifies an address in the process
where an interrupt is simulated.
An RTI instruction will return from the
interrupt.
As a signal is caught,
it is reset to 0.
Thus if it is desired to
catch every such signal,
the catching routine must
issue another
.it signal
call.
.s3
The starred signals in the list above
cause core images if not caught and not ignored.
In C,
if
.it func
is 0 or 1, the action is as described above.
If
.it func
is even, it is assumed to be the address
of a function entry point.
When the signal occurs,
the function will be called.
A return from the function will
simulate the RTI.
.s3
After a
.it fork,
the child inherits
all signals.
The
.it exec
call resets all
caught signals to default action.
.sh "SEE ALSO"
kill (I, II)
.sh DIAGNOSTICS
The error bit
(c-bit)
is set if the
given signal is out of range.
In C, a \*-1 indicates an error;
0 indicates success.
Commit	Line	Data
91d4927d KT	1	.th SIGNAL II 8/5/73
	2	.sh NAME
	3	signal \*- catch or ignore signals
	4	.sh SYNOPSIS
	5	(signal = 48.)
	6	.br
	7	.ft B
	8	sys signal; sig; value
	9	.s3
	10	signal(sig, func)
	11	.br
	12	int (*func)();
	13	.ft R
	14	.sh DESCRIPTION
	15	When the signal
	16	defined by
	17	.it sig
	18	is sent to the current process,
	19	it is to be treated according to
	20	.it value.
	21	The following is the list of signals:
	22	.s3
	23	.lp +10 5
	24	1 hangup
	25	.lp +10 5
	26	2 interrupt
	27	.lp +10 5
	28	3* quit
	29	.lp +10 5
	30	4* illegal instruction
	31	.lp +10 5
	32	5* trace trap
	33	.lp +10 5
	34	6* IOT instruction
	35	.lp +10 5
	36	7* EMT instruction
	37	.lp +10 5
	38	8* floating point exception
	39	.lp +10 5
	40	9 kill (cannot be caught or ignored)
	41	.lp +10 5
	42	10* bus error
	43	.lp +10 5
	44	11* segmentation violation
	45	.lp +10 5
	46	12* bad argument to sys call
	47	.s3
	48	.i0
	49	If
	50	.it value
	51	is 0, the default system
	52	action applies to the signal.
	53	This is processes termination
	54	with or without a core dump.
	55	If
	56	.it value
	57	is odd, the signal is ignored.
	58	Any other even
	59	.it value
	60	specifies an address in the process
	61	where an interrupt is simulated.
	62	An RTI instruction will return from the
	63	interrupt.
	64	As a signal is caught,
65	it is reset to 0.
66	Thus if it is desired to
67	catch every such signal,
68	the catching routine must
69	issue another
70	.it signal
71	call.
72	.s3
73	The starred signals in the list above
74	cause core images if not caught and not ignored.
75	In C,
76	if
77	.it func
78	is 0 or 1, the action is as described above.
79	If
80	.it func
81	is even, it is assumed to be the address
82	of a function entry point.
83	When the signal occurs,
84	the function will be called.
85	A return from the function will
86	simulate the RTI.
87	.s3
88	After a
89	.it fork,
90	the child inherits
91	all signals.
92	The
93	.it exec
94	call resets all
95	caught signals to default action.
96	.sh "SEE ALSO"
97	kill (I, II)
98	.sh DIAGNOSTICS
99	The error bit
100	(c-bit)
101	is set if the
102	given signal is out of range.
103	In C, a \*-1 indicates an error;
104	0 indicates success.