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DOS400UN.ZIP
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1988-11-12
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DOS 4.0 Undocumented Features
I've been playing around a bit with PC-Magazines RAMVIEW
program. An excellent program, allows you to really get into
hacking etc. Well anyway. A few days ago I found an
undocumented command in DOS 4.0 - TRUENAME. Well today,
accidentally, after formatting a disk, I found that the FORMAT
command has actually more parameters than stated in the manual!
Then I started to find if other commands have undocumented
features too. I didn't even bother checking commands like
BACKUP, RESTORE, MODE, XCOPY etc they have too many options
already, I'll leave it to someone else. So here's what I came
up with:
FORMAT:
/T, /N: Unknown. They each take a number,
in the format: /T:xxx/N:xxx. You
must use both of the switches
together.
/AUTOTEST: Go right on to formatting, do not
wait for confirmation, do not
display final message.
/BACKUP, /SELECT: Same as above. I guess these
switches are used by the SELECT
program and the BACKUP command.
SHELLC: These are additional options you can add to the @SHELLC
command in the DOSSHELL.BAT file. In the getting
started manual theres an explanation how to change
DOSSHELL switches, but here are some additional ones:
/CONFIRMDELETEON (Default) These are the options
/CONFIRMDELETEOFF that appear in the File
/CONFIRMREPLACEON (Default) options... menu in the
/CONFIRMREPLACEOFF File System. Whatever you
/ALLOWSELECTON change in that Menu is not
/ALLOWSELECTOFF (Default) going to be retained when
you invoke the shell again.
/SORTBYNAME You can set these switches
/SORTBYEXT to your liking so that each
/SORTBYSIZE time you go into the Shell
/SORTBYDATE you won't have to change
/SORTBYDISK them.
/ASC:filename.ASC You can specify from which file
you want the "Extension
Associations" to be read or
saved. This is useful if you are
networking DOS, so each user can
have his own Associations.
/NROOT, /DBCS, /ENH, I don't have the slightest idea
/REF, /PRE what these are.
/PRO:filename.PRO I don't know exactly what this
option does. I think it has
something to do with the printer,
since the GRAPHICS command uses a
file GRAPHICS.PRO to get info
about the different printers.
Another thing about DOSSHELL: In the manual it says
that you can't use the GOTO statement in the Commands:
field when adding a program to a group. However, if
you do, it will terminate DOSSHELL and throw you back
to DOS, saying "Label not found." There are two labels
that *do* work, COMMON and END. Entering GOTO COMMON
or GOTO END in the commands... field and running it
will have no affect. Strangely, COMMON and END are the
two labels used in DOSSHELL.BAT. Now try this: make a
new program in the shell, call it whatever you like.
In the commands... field enter GOTO ABCD, then press
F4, then type DIR and press F2 to save. Now run the
program. It will throw you out to dos, saying the
label wasn't found. Now type DOSSHELL - before going
into the shell, it will show you the directory! I came
to the conclusion that SHELLB, a resident program,
must be the "driver" of all programs run from the
DOSSHELL. SHELLB probably gets passed whatever
DOSSHELL wants it to execute, then SHELLB executes it
while the SHELL itself is not in memory. Then SHELLC
is called and you get back into the shell. This way
more memory is free for the programs that get executed.
ATTRIB:
You can specify, after a filename, one of the
following keywords. These keywords seem to exist only
to display the value, not to change it or anything.
The format is:
ATTRIB filename keyword or
ATTRIB [+/-][A/R] filename keyword.
FILESIZE: Reports the size of the file(s).
DATE, TIME: Report date or time of the file.
CP: Invalid parameter, but it was
there with the others.
CODEPAGE: Invalid parameter. This one is
strange. You type ATTRIB *.*
CODEPAGE and it says "Invalid
parameter - CP".
If anyone has found any other undocumented commands/switches/
whatever, please inform me, my GEnie Mail address is D.OZ1, or
send me mail via the QwikMail system.
Hope you enjoy....
>>> Doron. <<<