![[BACK]](/cvsweb/icons/back.gif){kind=icon}
Return to signal.2 CVS log ![[TXT]](/cvsweb/icons/text.gif){kind=icon}
![[DIR]](/cvsweb/icons/dir.gif){kind=icon}
Up to [Research Unix] / researchv10dc / man / man2|
Return to signal.2 CVS log | Up to [Research Unix] / researchv10dc / man / man2 |
1.1 root 1: .TH SIGNAL 2
2: .CT 2 proc_man
3: .SH NAME
4: signal, kill \(mi receive and send signals
5: .SH SYNOPSIS
6: .nf
7: .B #include <signal.h>
8: .PP
9: .B SIG_TYP signal(sig, func)
10: .B SIG_TYP func;
11: .PP
12: .B int kill(pid, sig)
13: .fi
14: .SH DESCRIPTION
15: A signal
16: is generated by some abnormal event
17: initiated by a user at a terminal (quit, interrupt),
18: by a program error (bus error, etc.),
19: or by
20: .I kill
21: in another process.
22: Normally, most signals
23: cause termination of the receiving process,
24: but
25: .I signal
26: allows them either to be ignored
27: or to be caught by interrupting to a specified function.
28: The following signal names are defined in
29: .FR <signal.h> :
30: .LP
31: .nf
32: .ta \w'SIGMMMM 'u +\w'15* 'u
33: \fLSIGHUP\fP 1 hangup
34: \fLSIGINT\fP 2 interrupt
35: \fLSIGQUIT\fP 3* quit
36: \fLSIGILL\fP 4* illegal instruction (not reset when caught)
37: \fLSIGTRAP\fP 5* trace trap (not reset when caught)
38: \fLSIGIOT\fP 6* IOT instruction
39: \fLSIGEMT\fP 7* EMT instruction
40: \fLSIGFPE\fP 8* floating point exception
41: \fLSIGKILL\fP 9 kill (cannot be caught or ignored)
42: \fLSIGBUS\fP 10* bus error
43: \fLSIGSEGV\fP 11* segmentation violation
44: \fLSIGSYS\fP 12* bad argument to system call
45: \fLSIGPIPE\fP 13 write on a pipe with no one to read it
46: \fLSIGALRM\fP 14 alarm clock
47: \fLSIGTERM\fP 15 software termination signal
48: 16 unassigned
49: \fLSIGSTOP\fP 17+ stop (cannot be caught or ignored)
50: \fLSIGCONT\fP 19# continue a stopped process
51: \fLSIGCHLD\fP 20# child has stopped or exited
52: .sp
53: .fi
54: * places core image in file
55: .B core
56: if not caught or ignored
57: .br
58: + suspends process until
59: .B SIGCONT
60: or
61: .BR PIOCRUN ;
62: see
63: .IR proc (4)
64: .br
65: # ignored if not caught
66: .PP
67: Signals 1 through
68: .BR NSIG -1,
69: defined in the include file, exist.
70: Those not listed above have
71: no conventional meaning in this system.
72: (Berkeley systems use 1-15 and 17-25.)
73: .PP
74: .I Signal
75: specifies how signal
76: .I sig
77: will be handled.
78: If
79: .I func
80: is
81: .BR SIG_DFL ,
82: the default action listed above is reinstated.
83: If
84: .I func
85: is
86: .BR SIG_IGN ,
87: the signal will be ignored.
88: Otherwise, when the signal occurs, it will be caught and
89: a function, pointed to by
90: .IR func ,
91: will be called.
92: The type of pointer
93: .I func
94: is
95: .BR SIG_TYP :
96: .IP
97: .B typedef int (*SIG_TYP)();
98: .LP
99: It must point to a function such as,
100: .EX
101: .L
102: int catcher(sig) { ... }
103: .EE
104: which will be called with a
105: signal number as argument.
106: A return from the catcher function will
107: continue the process at the point it was interrupted.
108: .PP
109: Except as indicated, a signal is reset to
110: .B SIG_DFL
111: after being caught.
112: Thus if it is desired to catch every such signal,
113: the catching routine must issue another
114: .I signal
115: call.
116: .PP
117: When a caught signal occurs
118: during certain system calls, the call terminates prematurely.
119: In particular this can occur during
120: .IR read (2)
121: or
122: .IR write
123: on a slow device (like a typewriter, but not a disk),
124: and during
125: .IR pause
126: and
127: .IR wait ;
128: see
129: .IR alarm (2)
130: and
131: .IR exit (2).
132: The interrupted system call will return error
133: .BR EINTR .
134: The user's program may then, if it wishes, re-execute the call.
135: .PP
136: .I Signal
137: returns the previous (or initial)
138: value of
139: .I func
140: for the particular signal.
141: .PP
142: After a
143: .IR fork (2)
144: the child inherits all signal settings.
145: .IR Exec (2)
146: resets all caught signals to default action.
147: .PP
148: .I Kill
149: sends signal
150: .I sig
151: to the process specified by process id
152: .I pid.
153: Signal 0
154: has no effect on the target process and may be used to
155: test the existence of a process.
156: The success of sending a signal is independent of how the receiving
157: process treats the signal.
158: .PP
159: The effective userid of the sending process must be either 0
160: or the effective userid of the receiving process.
161: .PP
162: If
163: .I pid
164: is 0, the signal is sent to all other processes in the
165: sender's process group; see
166: .IR stream (4).
167: .PP
168: If
169: .I pid
170: is \-1, and the user is the super-user,
171: the signal is broadcast universally
172: except to processes 0 (scheduler),
173: 1 (initialization)
174: and 2 (pageout); see
175: .IR init (8).
176: If
177: .I pid
178: is less than \-1,
179: it is negated
180: and taken as a process group
181: whose members should receive the signal.
182: .PP
183: Processes may send signals to themselves.
184: .SH FILES
185: .F core
186: .SH "SEE ALSO"
187: .IR kill (1),
188: .IR setjmp (3),
189: .IR stream (4)
190: .SH DIAGNOSTICS
191: .IR signal :
192: .B EINVAL
193: .br
194: .IR kill :
195: .BR EINVAL ,
196: .BR EPERM ,
197: .BR ESRCH
198: .SH BUGS
199: The reason for a trap should be distinguishable by extra arguments
200: to the signal handler.
201: .br
202: If a repeated signal arrives before the last one can be reset,
203: there is no chance to catch it.
204: .br
205: For historical reasons, the return value of
206: a catcher function is
207: .BR int ;
208: it is
209: .B void
210: in
211: .SM ANSI
212: standard C.
This archive runs on limited infrastructure. Preserving old code on modern bandwidth. Automated agents are requested to crawl responsibly.