sysv_signal(3) — Linux manual page


SYSV_SIGNAL(3)          Linux Programmer's Manual         SYSV_SIGNAL(3)

NAME         top

       sysv_signal - signal handling with System V semantics

SYNOPSIS         top

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

       typedef void (*sighandler_t)(int);

       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

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

       │Interface                             Attribute     Value   │
       │sysv_signal()                         │ Thread safety │ MT-Safe │

CONFORMING TO         top

       This function is nonstandard.

NOTES         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.

SEE ALSO         top

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

COLOPHON         top

       This page is part of release 5.13 of the Linux man-pages project.
       A description of the project, information about reporting bugs,
       and the latest version of this page, can be found at

                               2021-03-22                 SYSV_SIGNAL(3)

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