set42sig(3)                                           set42sig(3)



     NAME
          set42sig - set 4.2 BSD signal interface

     SYNOPSIS
          int set42sig()

     DESCRIPTION
          set42sig changes the signal interface to one closely resem-
          bling BSD 4.2 systems.  This call is similar to the setcom-
          pat system call. Unlike setcompat(2), set42sig arranges for
          the current compatibility flags to be logically OR'ed with
          the new flags.  set42sig is functionally equivalent to the
          following C code fragment:

          #include <compat.h>

          return (setcompat(getcompat() | COMPAT_BSDSIGNALS |
                  COMPAT_BSDTTY | COMPAT_BSDSYSCALLS));

          For the process calling it, it enables reliable signal
          delivery, the job control tty signals, and restarting of
          system calls when an interrupt is received.

          If the COMPAT_SVID flag is set before calling set42sig, both
          BSD 4.2 and System V modes are set and 4.2 BSD mode will
          have precedence.  COMPAT_SVID can be set in two ways, by
          calling setcompat(2) and by compiling the program with the
          -ZS flag option (see cc(1).

          All aspects of 4.2 signals are inherited across fork system
          calls. 4.2 job control group membership is inherited across
          exec system calls.  When exec is invoked, the inherited 4.2
          signals are lost and the signal-handling mechanism returns
          to System V style.  See setcompat(2) for more information.

     ERRORS
          [EINVAL]    The process has already arranged to catch sig-
                      nals.  Normally set42sig is called prior to any
                      other signal activity.

     SEE ALSO
          cc(1), setcompat(2), sigvec(2), signal(3), termio(7).













     April, 1990                                                     1