In message <Pine.OSF.3.95.970130093833.16880C-
[log in to unmask]>, "Dr. Ferenc Nagy" <[log in to unmask]>
writes

(In reply to an Email, but I think it went to the List too. I don't mind
that at all, but some of you might wonder what we are talking about,
which is how you suppress unwanted output from MPE. Ferenc wants to go
one stage further than I had previously considered, and suppress output
from *executed* MPE commands. As you will see, this is most desirable in
the context shown.)

>Hi Roy:
>Look at the folowing UDC. IF I invoke it with an existing file then I
>get no echo, as I want If I invoke it with an non-existing file then I
>get two lines on the screen but I need only the JCW setting withot echo.
>How can I suppress these two lines?
> :help exists
> USER DEFINED COMMAND
> exists file,jc=exists
> option nolist,help
> setjcw cierror=0
> continue
> listf !file;$null
> if cierror=907 then
>    setjcw !jc=0
> els
>    setjcw !jc=1
> endi
>
>
> :exists nonexfil
> LISTF NONEXFIL;$NULL
> NON-EXISTENT FILE.  (CIERR 907)
>
> :exists userproc
>
>               TIA
>                                              Frank
>
The joker is the two lines from the 'failed' LISTF, which Frank is using
to see if it exists.....

I don't think you can use FINFO, which gets over this, because it's not
in MPE/V. (Unless it's been retro-fitted recently. Can you check this?
If you have FINFO now, you can use that).

When I had this problem on Classics, I wrote a program to check for the
existence of a file - it accepted the filename, called FLABELINFO for
it, and set a dedicated JCW directly.

Alas, I don't have it any more, or I'd send it to you. It can't be hard
to write another though.It was the only way round those annoying lines
that I could find. Though there may be more ingenuity out there.....

Best solution that I have for now, builds on your 'invisible lines'
idea, but works on dumb terminals too. I did find that for the
'invisible line' string to work, the COMMENT must be transmitted, which
requires OPTION LIST on that UDC. So you would need at least a little
'flyback' sequence to cover that line!

My way is all flyback.First, add a new UDC, 'flyback' to 'exists' as
follows:

....
 if cierror=907 then
    flyback
    setjcw !jc=0
......

Then create the UDC 'flyback' as follows:

  flyback
  option list
  comment Esc&a-99c-2YEscMEscMEscMEscA

Replace each 'Esc' with a real Escape character, of course.
The commands are from the 2392A book and they:

Fly back up to 99 characters left, which should get to column 0
Fly back 2 lines upwards, over the lines you don't want shown.
Delete 3 lines downwards (your two, plus this line itself)
Fly back one upwards, so that you don't get a blank line.

The user may see the unwanted lines flicker on a slow terminal, and it
will scroll up if typed at the bottom of a screen, but it *works*.

OK. Now, how do we solve this for printers?

Best Regards

Roy
--
Roy Brown               Phone : (01684) 291710     Fax : (01684) 291712
Affirm Ltd              Email : [log in to unmask]
The Great Barn, Mill St 'Have nothing on your systems that you do not
TEWKESBURY GL20 5SB (UK) know to be useful, or believe to be beautiful.'