sysv_signal(3)

1sysv_signal(3)             Library Functions Manual             sysv_signal(3)
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NAME

6       sysv_signal - signal handling with System V semantics
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LIBRARY

9       Standard C library (libc, -lc)
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SYNOPSIS

12       #define _GNU_SOURCE         /* See feature_test_macros(7) */
13       #include <signal.h>
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15       typedef void (*sighandler_t)(int);
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17       sighandler_t sysv_signal(int signum, sighandler_t handler);
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DESCRIPTION

20       The  sysv_signal()  function takes the same arguments, and performs the
21       same task, as signal(2).
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23       However sysv_signal() provides the System V  unreliable  signal  seman‐
24       tics, that is: a) the disposition of the signal is reset to the default
25       when the handler is invoked; b) delivery of further  instances  of  the
26       signal  is not blocked while the signal handler is executing; and c) if
27       the handler interrupts (certain) blocking system calls, then the system
28       call is not automatically restarted.
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RETURN VALUE

31       The  sysv_signal()  function  returns  the previous value of the signal
32       handler, or SIG_ERR on error.
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ERRORS

35       As for signal(2).
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ATTRIBUTES

38       For an  explanation  of  the  terms  used  in  this  section,  see  at‐
39       tributes(7).
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41       ┌────────────────────────────────────────────┬───────────────┬─────────┐
42       │Interface                                   │ Attribute     │ Value   │
43       ├────────────────────────────────────────────┼───────────────┼─────────┤
44       │sysv_signal()                               │ Thread safety │ MT-Safe │
45       └────────────────────────────────────────────┴───────────────┴─────────┘
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VERSIONS

48       Use of sysv_signal() should be avoided; use sigaction(2) instead.
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50       On  older  Linux  systems, sysv_signal() and signal(2) were equivalent.
51       But on newer systems, signal(2) provides reliable signal semantics; see
52       signal(2) for details.
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54       The  use  of sighandler_t is a GNU extension; this type is defined only
55       if the _GNU_SOURCE feature test macro is defined.
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STANDARDS

58       None.
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