Mail Archives: opendos/2004/03/08/23:18:04
Hi folks,
I assume that quite a few DOS users inhere use JP Software's otherwise
excellent command processor 4DOS.COM as replacement for COMMAND.COM
or FREECOM.
It happens that with one of their recent builds (most probably 124 --
current build is 125) they silently but deliberately removed support
for the startup option /Y in order to invoke the batch file debugger.
/Y is supported by COMMAND.COM since MS-DOS 6.20, PC DOS 6.3, late
issues of Novell DOS 7, and by DR-DOS 7.02 and higher, and (like the
earlier /D) is used to communicate the user selected skip- (F5) and
single-stepping-(F8)-modes from the DOS BIOS to the shell.
If you had pressed F8 during startup and were single-stepping
CONFIG.SYS, the DOS BIOS would automatically add a /Y to the shell
command line, so that the invoked shell can continue to single-step
through AUTOEXEC.BAT. In particular, this is important when you
cannot manually edit the configuration files, for example, during
CD-ROM boot or such.
(NB. Of course, similar means also existed in the initial version of
Novell DOS 7 and in OpenDOS 7.01, but they didn't used the command
line interface, but communicated the status of the boot mode through
special settings retrieved via the pre-environment. This internal
interface is still supported in all recent issues of DR-DOS and
COMMAND.COM, so that you can easily mix different versions.
Unfortunately, 4DOS does not query this internal interface, although
this would have some advantages as it is more flexible and can report
some further single-stepping sub-modes to the shell so it could be
even more seamlessly integrated than just using /D and /Y. Also, this
interface could still continue to work, even if support for the option
/Y would be permanently removed in 4DOS. On the other hand, this
will only work for the DR-DOS family, as MS-DOS/PC DOS only support
the /Y and /D trick.)
/Y can also be used to single-step normal batchfiles, and according
to Rex Conn, head of JP Software, several system administrators did
complain that users would 'misuse' /Y in order to bypass some stuff
in the startup batchjobs, hence support for this option was silently
removed in one of the most recent builds (it's still in the help for
build 124, but doesn't work any more, in build 125 it has also been
removed from the help).
That they are thereby breaking an IMHO vital part of DOS compatibility
and cause significant inconveniences to users who have to single-step
their startup files in an emergency case does not seem to occur to
them it seems...
So, if you are a user of 4DOS, this mail is intended to inform you of
this modification, which otherwise may escape you until the next time
you have to single-step the configuration files and find this to be
no longer working...
If you do not agree with the change, I would like to encourage you
to voice your opinion in JP Software's support forum and ask them
to reenable the previous behaviour, just as I did. Or, if you prefer
that this option be removed, you can also state this there. ;-)
Otherwise, I'd like to suggest that you keep hold of the last
4DOS build which still has this option enabled. (I think, it was
4DOS 7.50 build 122, but right now I am not completely sure about
this, as I didn't had any time to follow and update every new build
in the past months myself, so I will have to find out myself now
as well.)
Hope it helps to keep you from stepping into a trap by "upgrading"
to the latest build.
Greetings,
Matthias
--
<mailto:Matthias DOT Paul AT post DOT rwth-aachen DOT de>; <mailto:mpaul AT drdos DOT org>
http://www.uni-bonn.de/~uzs180/mpdokeng.html; http://mpaul.drdos.org
"Programs are poems for computers."
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