Some undocumented things with turned off command extensions

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npocmaka_
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Some undocumented things with turned off command extensions

#1 Post by npocmaka_ » 11 Feb 2017 06:16

these variables are not accessible - CMDCMDLINE , TIME , DATE , RANDOM , ERRORLEVEL , CMDEXTVERSION , CD (but __CD__ is still there)


COLOR command is not working.
Last edited by npocmaka_ on 11 Feb 2017 09:42, edited 1 time in total.

penpen
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Re: Some undocumented things with turned of command extensions

#2 Post by penpen » 11 Feb 2017 07:07

The following is not undocumented - but the documentation is just wrong (at least the german version).

The setlocal always accepts the command line arguments (even if extensions are disabled):
- "enableExtensions" and
- "enableDelayedExpansion".


penpen

aGerman
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Re: Some undocumented things with turned of command extensions

#3 Post by aGerman » 11 Feb 2017 07:11

It's interesting that the color command doesn't work :?

As to the dynamic variables - actually it's documented behavior. Have a look at the help message of SET. The explanation of these variables begins with "If Command Extensions are enabled ...".
http://www.dostips.com/DosCommandIndex.php#SET

Steffen

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Re: Some undocumented things with turned of command extensions

#4 Post by npocmaka_ » 11 Feb 2017 09:47

aGerman wrote:As to the dynamic variables - actually it's documented behavior. Have a look at the help message of SET. The explanation of these variables begins with "If Command Extensions are enabled ...".
http://www.dostips.com/DosCommandIndex.php#SET

Steffen


I should read the documentation more carefully.
Though for the color I've found nothing.

mcnd
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Re: Some undocumented things with turned off command extensions

#5 Post by mcnd » 11 Feb 2017 11:30

COLOR, ASSOC and FTYPE are associated to command extensions but are not documented as dependent on them.

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Re: Some undocumented things with turned off command extensions

#6 Post by npocmaka_ » 11 Feb 2017 14:25

mcnd wrote:COLOR, ASSOC and FTYPE are associated to command extensions but are not documented as dependent on them.

So assoc and ftype will not work also?

EDIT
Just tried. They are not working. Thanks for the info.

Sponge Belly
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Re: Some undocumented things with turned off command extensions

#7 Post by Sponge Belly » 12 Feb 2017 11:18

Hello All! :)

Interesting discussion. I’d like to add the following observations made while extensions were disabled.

The PROMPT command doesn’t work. Neither does:

Code: Select all

set "prompt=@"


Otoh…

Code: Select all

set prompt=@


does work. :?

And another thing I’ve noticed is that if there are 2 labels with the same name, GOTO will jump to the 2nd label. Yet another example of CMD’s eccentric behaviour.

BFN!

- SB

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Re: Some undocumented things with turned off command extensions

#8 Post by jeb » 12 Feb 2017 12:50

Code: Select all

set "prompt=something"

Fails as the extended SET-syntax is no longer valid in the disbaled extension context.

I can't reproduce your goto :label problem.
I can't believe it, as any goto normally starts a search from the current file position to the first matching label.

Code: Select all

@echo off
setlocal DisableExtensions

goto :myLabel

:myLabel
echo First
goto :eof

:myLabel
echo Second
goto :eof

:eof


This outputs, as expected, "First".

Btw. You need to define the :eof label, as it doesn't exists without extensions.
Curious is the error message of "exit /b" in this context.
Free translation from german wrote:The label - :EOF can't be found

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Re: Some undocumented things with turned off command extensions

#9 Post by npocmaka_ » 12 Feb 2017 14:20

jeb wrote:
Btw. You need to define the :eof label, as it doesn't exists without extensions.
Curious is the error message of "exit /b" in this context.
Free translation from german wrote:The label - :EOF can't be found


So exit uses goto to find the end of the file?

Should this mean that goto :eof works faster than exit /b ?

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Re: Some undocumented things with turned off command extensions

#10 Post by aGerman » 12 Feb 2017 14:30

npocmaka_ wrote:Should this mean that goto :eof works faster than exit /b ?

Most likely. Since you can pass a return value to exit /b the cmd has to evaluate a potential 3rd argument.

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Re: Some undocumented things with turned off command extensions

#11 Post by Sponge Belly » 12 Feb 2017 15:23

Hi Again! :)

I noticed the GOTO glitch when playing around with the code developed in the Foolproof Counting of Arguments topic. I’ve boiled it down to this:

Code: Select all

@echo off & setlocal enableextensions disabledelayedexpansion

(
goto skip
:skip
echo(first label
)

:skip
echo(second label

endlocal & goto :eof


The first ECHO statement is skipped, but change the second label name and both ECHO statements will be executed! :o

Btw, I had to revise this post with simpler code… twice! I now realise this phenomenon has nothing to do with disabled extensions. :oops:

- SB
Last edited by Sponge Belly on 14 Feb 2017 12:58, edited 1 time in total.

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Re: Some undocumented things with turned off command extensions

#12 Post by penpen » 12 Feb 2017 17:22

Sponge Belly wrote:The ampersand (&) can’t be used as command separator when extensions are disabled.
What do you mean, by saying the above?
The following should work as always: "&", "&&", "|", "||".


The command line interpreter must read the complete "for"-loop before it is able to execute it.
Because of that the filepointer is in the line after the ")", and the next ":skip" label is the second in the batch.

If you change the second label, then the cli will find the only ":skip"-label in this batch, because it is not in the same line as the ")" line.


penpen

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Re: Some undocumented things with turned off command extensions

#13 Post by Sponge Belly » 14 Feb 2017 13:11

Hi Penpen,

Thanks for explaining GOTO’s mysterious behaviour. And you don’t need the body of a FOR loop or an IF block. An unconditional parenthesized block will do. See my previous post for a simplified code example.

And you’re right about the ampersand as command separator. I don’t know what I was thinking. I've removed the erroneous postscript from my previous post. :oops:

Finally, GOTO :EOF will work with extensions disabled, but :EOF must be in capitals.

- SB

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