🚀 go-pugleaf

CHAMINADE, MARC MICHEL LOUIS <MCHAMINA@ESTEC.BITNET> writes:

>If you want to prevent people to delete your files on your hd with the f
nction
>del xxx.x rather than Attrib you'd better rename the files from
>xxx.x to
> xxx.x The space in front of the name is obtained with the alt-255 combi
ation.
>You can not call the file or do anything to it by using the space key.

>Some may find it usefull. I do !

Nifty idea ... I've got an extension to that:

Since DOS see the ALT-255 combo as a valid character for filename, you
aren't limited to just one of them.  You can create a filename that is
nothing but ALT-255's.  -OR-, you can put an ALT-255 at the _end_ of the
name:

     xxx_.x

where the '_' is the ALT-255 combo.  That way, the file doesn't seem any
different when you do a directory of it ... yet trying to access just
xxx.x doesn't work (file not found).

Also, ALT-255 works for creating sub-directories.  It will effectively
make the directory invisible unless something is entered into the
directory table after it.

(for those curious, ALT-255 means hold down the alt key and type 2 5 5 on
the _numeric_keypad_.  You won't get this to work if you use the keys
across the top of the keyboard, it _must_ be the keypad.  For that matter,
that's how you can create filenames or directories with IBM graphics
characters:  simply substitute the ALT-??? combo of the character for what
you want ... the combo being the ASCII value of the graphic char you want
to use).

-Scotty

Here's another nifty use for ALT-255:

In batch files,

    echo_

where _ is ALT-255, will print a blank line on the screen.
This is useful if you want to separate your output messages.
And it works from DOS 2.11 and up!

The tricky thing, though, is to find an editor which will
let you enter it--not all do!  Of course, copy con batch.bat
*will* work.  :^)

Later,
Kevin

In article <92238.135238MCHAMINA@ESTEC.BITNET> MCHAMINA@ESTEC.BITNET (CHAMINADE, MARC MICHEL LOUIS) writes:
>From: MCHAMINA@ESTEC.BITNET (CHAMINADE, MARC MICHEL LOUIS)
>Subject: alt 255
>Date: 25 Aug 92 22:31:59 GMT

>If you want to prevent people to delete your files on your hd with the function
>del xxx.x rather than Attrib you'd better rename the files from
>xxx.x to
> xxx.x The space in front of the name is obtained with the alt-255 combination.
>You can not call the file or do anything to it by using the space key.

>Some may find it usefull. I do !

From a program, you can actually put a space (ASCII 32) in the filename.  
This will prevent some hacker from using the alt-255 trick to delete your 
file.  Of course, if you create a file ' abc.xyz', it can be gotten rid of
with the command 'del *.xyz'.

 ----------------------------------------------------------------------------
    "This must be Thursday.  I never could get the hang of Thursdays"
                                                       - D Adams
  - Patrick Taylor
    Ericsson Network Systems
    exuptr@exu.ericsson.se                       "Don't let the .se fool you"
    alternately, exuptr@ZGNews.Lonestar.Org

odonovan@ohstpy.mps.ohio-state.edu writes:

>Here's another nifty use for ALT-255:

>In batch files,

>    echo_

>where _ is ALT-255, will print a blank line on the screen.
>This is useful if you want to separate your output messages.
>And it works from DOS 2.11 and up!

Why not just code:

echo.

which writes a single blank line to the screen?  (Note the period after
the "o".)  This worked at least in 3.3; I'm not sure if it is valid for
any earlier releases.

Using ECHO. is documented for MS-DOS 5 on page 458 of the DOS manual.

Joe Morris / MITRE

exuptr@exu.ericsson.se (exuptr@exu.ericsson.se) writes:
>From a program, you can actually put a space (ASCII 32) in the filename.  
>This will prevent some hacker from using the alt-255 trick to delete your 
>file.  Of course, if you create a file ' abc.xyz', it can be gotten rid of
>with the command 'del *.xyz'.

Or with any decent sector editor or directory-maintainence program
like Xtree.  There's virtually no way of stopping a determined hacker,
but tricks like this are good for keeping newbies out of things.  I
used to use the alt-255 thing to keep people from playing my Rogue
games at school...

swehtam bob

exuptr@exu.ericsson.se (exuptr@exu.ericsson.se) writes:

>From a program, you can actually put a space (ASCII 32) in the filename.  
>This will prevent some hacker from using the alt-255 trick to delete your 
>file.  Of course, if you create a file ' abc.xyz', it can be gotten rid of
>with the command 'del *.xyz'.

In the academic computer lab I worked in, this used to happen all the
time.  The word perfect books said to save the first exercise as
"CHAPT11 .EX1" and the students always did.  :-)

We deleted it with 'del chapt11?.ex1'....

-- 
Rich Holland              | INTERNET: holland@matt.ksu.ksu.edu
100 Jardine Terr, Apt A7  | BITNET  : holland@ksuvm
Manhattan, KS  66502-3357 | UUCP    : ...!rutgers!matt.ksu.ksu.edu!holland
"Jesus saves...but Gretzky gets the rebound!  He shoots!  He scores!!"

Is this ALT-255 thing a function of DOS or is it built into the keyboard BIOS?

If the former is the case, it doesn't work with DOS 5 + 4DOS 4 + ansi.sys .

If the latter is the case, it doesn't work with my chips.

No big deal, but I'm just curious....
-- 
Matt Garretson                       :-)                          garrem@rpi.edu

garrem@aix.rpi.edu (Matthew Olsen Garretson) writes:

>Is this ALT-255 thing a function of DOS or is it built into the keyboard BIOS?

>If the former is the case, it doesn't work with DOS 5 + 4DOS 4 + ansi.sys .

>If the latter is the case, it doesn't work with my chips.

The ability to generate an arbitrary byte is the responsibility of the
program which fields the keyboard interrupts.

If nobody is trying to be cute, it's the BIOS which interprets <ALT>+digits
as a one-byte character.  Programs which take over the keyboard hardware
interface -- such as Windows -- are responsible for providing the same
feature.

I can't speak for 4DOS because I don't run it.

BTW: the <ALT>+digit construct works only for the *keypad* digit keys.  It
will not work if you try to use the digit keys on the top row of the standard
QWERTY keyboard.

Joe Morris / MITRE