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NAME

       bsd_signal - signal handling with BSD semantics

SYNOPSIS

       #define _XOPEN_SOURCE
       #include <signal.h>

       typedef void (*sighandler_t)(int);

       sighandler_t bsd_signal(int signum, sighandler_t handler);

DESCRIPTION

       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

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

ERRORS

       As for signal(2).

CONFORMING TO

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

NOTES

       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 only defined
       if the _GNU_SOURCE feature test macro is defined.

SEE ALSO

       sigaction(2),   signal(2),   sysv_signal(3),    feature_test_macros(7),
       signal(7)

COLOPHON

       This  page  is  part of release 3.24 of the Linux man-pages project.  A
       description of the project, and information about reporting  bugs,  can
       be found at http://www.kernel.org/doc/man-pages/.

                                  2009-03-15