bsd_signal(3) — Linux manual page


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

NAME         top

       bsd_signal - signal handling with BSD semantics

SYNOPSIS         top

       #include <signal.h>

       typedef void (*sighandler_t)(int);

       sighandler_t bsd_signal(int signum, sighandler_t handler);

   Feature Test Macro Requirements for glibc (see

           Since glibc 2.26:
               _XOPEN_SOURCE >= 500
                   && ! (_POSIX_C_SOURCE >= 200809L)
           Glibc 2.25 and earlier:

DESCRIPTION         top

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

       The difference between the two is that bsd_signal() is guaranteed
       to provide reliable signal semantics, that is: a) the disposition
       of the signal is not reset to the default when the handler is
       invoked; b) delivery of further instances of the signal is
       blocked while the signal handler is executing; and c) if the
       handler interrupts a blocking system call, then the system call
       is automatically restarted.  A portable application cannot rely
       on signal(2) to provide these guarantees.

RETURN VALUE         top

       The bsd_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   │
       │bsd_signal()                          │ Thread safety │ MT-Safe │

CONFORMING TO         top

       4.2BSD, POSIX.1-2001.  POSIX.1-2008 removes the specification of
       bsd_signal(), recommending the use of sigaction(2) instead.

NOTES         top

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

       On modern Linux systems, bsd_signal() and signal(2) are
       equivalent.  But on older systems, signal(2) provided unreliable
       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), sysv_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                  BSD_SIGNAL(3)

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