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



NAME
       sysv_signal - signal handling with System V semantics

SYNOPSIS
       #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
       The  sysv_signal()  function takes the same arguments, and performs the same task, as sig‐
       nal(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
       The sysv_signal() function returns the previous value of the signal handler, or SIG_ERR on
       error.

ERRORS
       As for signal(2).

ATTRIBUTES
   Multithreading (see pthreads(7))
       The sysv_signal() function is thread-safe.

CONFORMING TO
       This function is nonstandard.

NOTES
       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 sys‐
       tems, 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
       sigaction(2), signal(2), bsd_signal(3), signal(7)

COLOPHON
       This  page  is  part of release 3.74 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 http://www.kernel.org/doc/man-pages/.



                                            2014-01-06                             SYSV_SIGNAL(3)