BSD_SIGNAL(3)						   BSD Library Functions Manual 					     BSD_SIGNAL(3)

NAME

     bsd_signal -- simplified signal facilities

SYNOPSIS

     #include <signal.h>

     void (*
     bsd_signal(int sig, void (*func)(int)))(int);

     or in an equivalent but easier to read typedef'd version:

     typedef void (*sig_t) (int);

     sig_t
     bsd_signal(int sig, sig_t func);

DESCRIPTION

     The bsd_signal() function provides a partially compatible interface for programs written to historical system interfaces (see USAGE below).

     The function call bsd_signal(sig, func) has the effect as if implemented as:

	   void (*bsd_signal(int sig, void (*func)(int)))(int)
	   {
	       struct sigaction act, oact;

	       act.sa_handler = func;
	       act.sa_flags = SA_RESTART;
	       sigemptyset(&act.sa_mask);
	       sigaddset(&act.sa_mask, sig);
	       if (sigaction(sig, &act, &oact) == -1)
		   return(SIG_ERR);
	       return(oact.sa_handler);
	   }

     The handler function should be declared:

	   void func(int sig)

     where sig is the signal number.  The behavior is undefined if func() is a function that takes more than one argument, or an argument of a
     different type.

RETURN VALUES

     Upon successful completion, bsd_signal() returns the previous action for sig.  Otherwise, SIG_ERR is returned and errno is set to indicate
     the error.

ERRORS

     Refer to sigaction(2).

USAGE

     This function is a direct replacement for the BSD signal(3) function for simple applications that are installing a single-argument signal
     handler function.	If a BSD signal handler function is being installed that expects more than one argument, the application has to be modi-
     fied to use sigaction(2).	The bsd_signal() function differs from signal(3) in that the SA_RESTART flag is set and the SA_RESETHAND will be
     clear when bsd_signal() is used.  The state of these flags is not specified for signal(3).

SEE ALSO

     sigaction(2), sigaddset(3), sigemptyset(3), signal(3)

STANDARDS

     The bsd_signal() function conforms to IEEE Std 1003.1-2001 (``POSIX.1'').

BSD
								 December 20, 2003							       BSD