Generates a specified software signal, which invokes the action
    routine established by a signal, ssignal, or sigvec function.

    Format

      #include  <signal.h>

      int gsignal  (int sig [, int sigcode]);

1 - Arguments

 sig

    The signal to be generated.

 sigcode

    An optional signal code. For example, signal SIGFPE-the
    arithmetic trap signal-has 10 different codes, each representing
    a different type of arithmetic trap.

    The signal codes can be represented by mnemonics or numbers. The
    arithmetic trap codes are represented by the numbers 1 to 10, but
    the SIGILL codes are represented by the numbers 0 to 2. The code
    values are defined in the <signal.h> header file.

2 - Description

    Calling the gsignal function has one of the following results:

    o  If gsignal specifies a sig argument that is outside the range
       defined in the <signal.h> header file, then gsignal returns 0
       and sets errno to EINVAL.

    o  If signal, ssignal, or sigvec establishes SIG_DFL (default
       action) for the signal, then gsignal does not return. The
       image is exited with the OpenVMS error code corresponding to
       the signal.

    o  If signal, ssignal, or sigvec establishes SIG_IGN (ignore
       signal) as the action for the signal, then gsignal returns its
       argument, sig.

    o  signal, ssignal, or sigvec must be used to establish an action
       routine for the signal. That function is called and its return
       value is returned by gsignal.

    See the Error and Signal Handling chapter of the C RTL Reference
    Manual for more information.

    See also raise, signal, ssignal, and sigvec.

3 - Return Values

    0                  Indicates a sig argument that is outside the
                       range defined in the <signal.h> header file;
                       errno is set to EINVAL.
    sig                Indicates that SIG_IGN (ignore signal) has
                       been established as the action for the signal.
    x                  Indicates that signal, ssignal, or sigvec has
                       established an action function for the signal.
                       That function is called, and its return value
                       is returned by gsignal.