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c11b1abf | 1 | .\" Copyright (c) 2007 Michael Kerrisk <mtk.manpages@gmail.com> |
7594eb92 | 2 | .\" |
93015253 | 3 | .\" %%%LICENSE_START(VERBATIM) |
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4 | .\" Permission is granted to make and distribute verbatim copies of this |
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4b72fb64 | 23 | .\" %%%LICENSE_END |
7594eb92 | 24 | .\" |
fe0fefbf | 25 | .TH SYSV_SIGNAL 3 2015-03-02 "" "Linux Programmer's Manual" |
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26 | .SH NAME |
27 | sysv_signal \- signal handling with System V semantics | |
28 | .SH SYNOPSIS | |
b80f966b | 29 | .BR "#define _GNU_SOURCE" " /* See feature_test_macros(7) */" |
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30 | .br |
31 | .B #include <signal.h> | |
68e4db0a | 32 | .PP |
7594eb92 | 33 | .B typedef void (*sighandler_t)(int); |
68e4db0a | 34 | .PP |
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35 | .BI "sighandler_t sysv_signal(int " signum ", sighandler_t " handler ); |
36 | .SH DESCRIPTION | |
37 | The | |
38 | .BR sysv_signal () | |
39 | function takes the same arguments, and performs the same task, as | |
40 | .BR signal (2). | |
847e0d88 | 41 | .PP |
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42 | However |
43 | .BR sysv_signal () | |
44 | provides the System V unreliable signal semantics, that is: | |
45 | a) the disposition of the signal is reset to the default | |
46 | when the handler is invoked; | |
47 | b) delivery of further instances of the signal is not blocked while | |
48 | the signal handler is executing; and | |
49 | c) if the handler interrupts (certain) blocking system calls, | |
50 | then the system call is not automatically restarted. | |
47297adb | 51 | .SH RETURN VALUE |
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52 | The |
53 | .BR sysv_signal () | |
54 | function returns the previous value of the signal handler, or | |
55 | .B SIG_ERR | |
56 | on error. | |
57 | .SH ERRORS | |
58 | As for | |
59 | .BR signal (2). | |
2b2d07c0 | 60 | .SH ATTRIBUTES |
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61 | For an explanation of the terms used in this section, see |
62 | .BR attributes (7). | |
63 | .TS | |
64 | allbox; | |
65 | lb lb lb | |
66 | l l l. | |
67 | Interface Attribute Value | |
68 | T{ | |
2b2d07c0 | 69 | .BR sysv_signal () |
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70 | T} Thread safety MT-Safe |
71 | .TE | |
47297adb | 72 | .SH CONFORMING TO |
c8f2dd47 | 73 | This function is nonstandard. |
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74 | .SH NOTES |
75 | Use of | |
76 | .BR sysv_signal () | |
77 | should be avoided; use | |
78 | .BR sigaction (2) | |
79 | instead. | |
847e0d88 | 80 | .PP |
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81 | On older Linux systems, |
82 | .BR sysv_signal () | |
83 | and | |
84 | .BR signal (2) | |
85 | were equivalent. | |
988db661 | 86 | But on newer systems, |
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87 | .BR signal (2) |
88 | provides reliable signal semantics; see | |
89 | .BR signal (2) | |
90 | for details. | |
847e0d88 | 91 | .PP |
7594eb92 | 92 | The use of |
f19a0f03 | 93 | .I sighandler_t |
7594eb92 | 94 | is a GNU extension; |
33a0ccb2 | 95 | this type is defined only if |
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96 | the |
97 | .B _GNU_SOURCE | |
98 | feature test macro is defined. | |
47297adb | 99 | .SH SEE ALSO |
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100 | .BR sigaction (2), |
101 | .BR signal (2), | |
102 | .BR bsd_signal (3), | |
7594eb92 | 103 | .BR signal (7) |