sysv_signal(3) — Linux manual page

sysv_signal(3)           Library Functions Manual          sysv_signal(3)

NAME         top

       sysv_signal - signal handling with System V semantics

LIBRARY         top

       Standard C library (libc, -lc)

SYNOPSIS         top

       #define _GNU_SOURCE         /* See feature_test_macros(7) */
       #include <signal.h>

       typedef typeof(void (int))  *sighandler_t;

       sighandler_t sysv_signal(int signum, sighandler_t handler);

DESCRIPTION         top

       The sysv_signal() function takes the same arguments, and performs
       the same task, as signal(2).

       However sysv_signal() provides the System V unreliable signal
       semantics, that is: a) the disposition of the signal is reset to
       the default when the handler is invoked; b) delivery of further
       instances of the signal is not blocked while the signal handler is
       executing; and c) if the handler interrupts (certain) blocking
       system calls, then the system call is not automatically restarted.

RETURN VALUE         top

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

ERRORS         top

       As for signal(2).

ATTRIBUTES         top

       For an explanation of the terms used in this section, see
       attributes(7).
       ┌──────────────────────────────────────┬───────────────┬─────────┐
       │ Interface                            │ Attribute     │ Value   │
       ├──────────────────────────────────────┼───────────────┼─────────┤
       │ sysv_signal()                        │ Thread safety │ MT-Safe │
       └──────────────────────────────────────┴───────────────┴─────────┘

VERSIONS         top

       Use of sysv_signal() should be avoided; use sigaction(2) instead.

       On older Linux systems, sysv_signal() and signal(2) were
       equivalent.  But on newer systems, signal(2) provides reliable
       signal semantics; see signal(2) for details.

       The use of sighandler_t is a GNU extension; this type is defined
       only if the _GNU_SOURCE feature test macro is defined.

STANDARDS         top

       None.

SEE ALSO         top

       sigaction(2), signal(2), bsd_signal(3), signal(7)

COLOPHON         top

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Linux man-pages 6.15            2025-05-17                 sysv_signal(3)

Pages that refer to this page: signal(2),  bsd_signal(3),  signal(7)

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