Microsoft Undocumented Features 1.7
Yves Bellefeuille
I'm reposting here a list of "Microsoft Undocumented Features" from
FidoNet. I thought it might be of interest to users of this group.
Yves Bellefeuille
- -
The
Fabulous BatPower
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List
(MicroSoft's Undocumented Features)
Volume 1 Number 7
===============================================================================
1) ATTRIB
ATTRIB ,
To remove all file attributes, from files in the directory you are
in, type:
attrib ,
Works for dos 5 and above... be careful with this one... I haven't
tried it with the /s extension.
Frank Ganje
ATTRIB ,|ECHO Y|DEL *.*
I originally put forward the above suggestion. It was a one line
command that could delete ALL files in the current directory. But
of course there is no point in typing it in at the dos prompt as
the person is there to press y at the right time. In a batch file
you would naturally split this command in two.
"Attrib ," can be used with the /S switch, so if entered in the
root directory you could reset _ALL_ attributes of _ALL_ files on
the _ENTIRE_ drive.
Richard Gallagher
Does this really work? I tried a previous suggestion, and it
didn't. I don't see the reason to pipe the attrib output to the
echo command.
Bruce Bowman
Worked fine here, took out all the files (system, hidden, read-only),
like a dream with no lock up, using MSDos 5.0
Terry Kreft
What version of DOS do you have? It works fine with DOS 5.
This is one way of stacking multiple commands on one line.
It is not really piping the output of attrib to echo. Using the
pipe is one way of stacking multiple commands on a line. All the
"attrib ," does is reset _ALL_ attributes on _ALL_ files in the
current directory. So if you were to run that from the root of
your c: drive you would no longer have a bootable drive.
Jim Banghart
(EDITOR'S NOTE: See the Multiple DOS Commands per Line section
for additional information)
I use DOS 5 also, and it doesn't always work. I do not recommend
this practice. It does attempt to pipe the output of attrib to echo,
and thus writes a file to the directory specified by the environment
variable TEMP. If you try to run this program in your TEMP directory,
you will get a sharing violation. It also actually slows your program,
because it has to write and delete a useless file (unless you have
your TEMP on a ramdisk).
I can't say I see much reason for stacking commands like this - put
the commands on separate lines. A character is a character, be it a
carriage return or a pipe, and your files will be easier to
understand.
Try running it in your TEMP directory. You will get a share violation
because ATTRIB will write a file to that directory. Better to split
the commands on two lines; avoid fostering bad habits.
Bruce Bowman
This does not work under Desqview. If you want to use it under DOS it
can also be shortened to:
attrib,|echo y|del.
Terry Blount
It depends on what directory you run it in. DV hooks the interrupts
for fatal errors and sharing violations, so it catches errors better
than DOS does. Try running it somewhere other than your TEMP directory,
or the directory in which your batch file resides, and it should work
okay.
Bruce Bowman
ATTRIB +H
Is there anyway to create a hidden directory on a hard drive?
I've since learned that DOS 5.0 ATTRIB can do the same thing
from the command line:
ATTRIB +h dirname
Gary Smith
===============================================================================
2) CALL
The DOS 5.0 manual, in the command reference for CALL, states:
Syntax: call [drive:][path]filename [batch-parameters]
Parameters [drive:][path]filename
Specifies the name and location of the batch program you
want to call. Filename must have a .BAT extension.
The latter sentence is not true in DOS 5.0. CALL works
equally well whether "filename" is a .BAT, .COM, or .EXE
file, or even internal command the following all work
just fine:
call dir
call mem
call tree
call echo Phhhhhhht!
Gary Smith
Is it safe to use CALL filename even if filename is a .COM or an .EXE
file as opposed to a .BAT file? I know it works; I'm just curious if
it's not good to do so.
George Steinmetz
The MS-DOS dox are silent on the issue, but I have done it on a number
of systems in just the situation you describe, where I didn't know in
advance if a .COM, .EXE, or .BAT file would be called.
I have *never* had a problem with it, and it doesn't seem to use any
more memory either.
Gary Novosielski
As far as DOSKEY macros go, I don't think you can run them from
batch files so they're no problem.
Erik Ratcliffe
I can confirm that, Erik. The DOSKEY command can be used within a
batch file to create a macro, but you cannot run a macro from a
batch file.
John Evans
I beg to differ, since no-one else appears to have jumped in on this
one. Try the following:
@echo off
doskey fred=dir/w
echo fred | call
Rudy Lacchin
The online Help states quite clearly that it is _not_ possible to
run a macro from within a batchfile.
OTOH, "echo", "|" and "call" are all documented, so one could argue
that it falls under the category "tips and tricks".
What puzzles me is that "call {macroname}" doesn't work but "echo
{macroname} | call" does?!?
John Evans
This puzzled me at first but isn't this what is happening; when you
put CALL FRED, then CALL is looking for an executable (com,bat,exe
file) to call, as it doesn't exist it fails (Bad Command...(?)), but
ECHO FRED|CALL, actually sends the output of FRED which is dir/w to
call and so as dir/w is a valid call statement it succeeds.
To prove this I made batch files with the following commands, which
gave the associated results:
doskey fred=dir/w Succeeded and gave a dir/w listing.
echo fred|call
doskey fred=dir/w Failed with a "Bad command or filename"
call fred error.
call dir/w succeeded and gave a dir/w listing
So I think my reasoning is correct. First time for everything.
Terry Kreft
===============================================================================
3) CHKDSK
EDITOR'S NOTE:
Technically the following information is NOT a MUF, but is included
here due to the fact that it may help save someone a lot of grief!
Similar to advising others not to use delayed cache writes and DOS
6.0's DoubleSpace.
CHKDSK
Can you tell me the _date_ of the BAD CHKDSK? I live in
fear of it as I mainly work on other peoples computers an I
have no way of telling if I will destroy their HD with a
simple chkdsk command!
Wallace Mcgee
The only problem with CHKDSK is with large partitions where DOS uses
a 256-sector FAT. Specifically with partition sizes in the ranges of:
127MB-129MB
254MB-258MB
508MB-516MB
1018MB-1030MB
2035MB-2061MB
The date of the CHKDSK that has that problem is 04/09/91. The
replacement being dated 11/11/91.
UNDELETE has the same problem for the same reason.
Bottom line is - if you don't have partitions in these size ranges -
you don't have a problem.
The corrected versions can be had by downloading from the MS BBS.
Probably also available off of CompuServ. The file to look for is:
PD0646.EXE. The phone number for the MS BBS is (206) 936-6735.
Hope that helps you and others with the same question.
Steve Osterday
From Microsoft:
INTRODUCTION
The Microsoft MS-DOS CHKDSK and UNDELETE commands dated 04/09/91,
which are included in the Microsoft MS-DOS 5 Upgrade, do not work
correctly on logical drives that require 256 sectors to store each
copy of the file allocation table (FAT). If any of the partitions
on your hard disk drive are within the ranges listed in the
following section and you do not have version 5.0a of the
Microsoft MS-DOS 5 Upgrade, which includes CHKDSK.EXE and
UNDELETE.EXE files dated 11/11/91, install the updated CHKDSK.EXE
and UNDELETE.EXE files included with this application note.
If your FAT occupies 256 sectors, using the CHKDSK.EXE file dated
04/09/91 with the /f parameter ("chkdsk /f" [without the quotation
marks]) can result in data loss. Using the UNDELETE.EXE file dated
04/09/91 can lead to unpredictable results.
DETERMINING IF YOU NEED TO INSTALL THE UPDATED FILES
Drives require a 256-sector FAT if they have partitions within the
size ranges listed below. Because the potential problems are serious,
these ranges include a margin of safety.
127 MB-129 MB
254 MB-258 MB
508 MB-516 MB
1018 MB-1030 MB
2035 MB-2061 MB
You can use the Fdisk program to determine if you have a 256-sector
FAT with the following procedure:
1. At the MS-DOS command prompt, type the following and press the
ENTER key:
fdisk
2. Press 4 on the keyboard to select the Display Partition Information
option and press ENTER.
3. The primary partition size is listed under the Mbytes heading. If
the size falls within any of the ranges specified above, install
the updated CHKDSK.EXE and UNDELETE.EXE files on the enclosed
PD0646 disk.
4. If you have an extended partition, press the ENTER key to view
those partition sizes. If any of the extended partition sizes
listed under the Mbytes heading fall within the ranges specified
above, install the CHKDSK.EXE and UNDELETE.EXE files on the
enclosed PD0646 disk.
5. Press the ESC key twice to exit to the MS-DOS command prompt.
Posted by: Vernon Frazee
In just about all versions of Dos (At LEAST Msdos though I've been
told others have the same problem), You cannot normally use a hard
drive which has more than 1024 Cylinders. It isn't a limitation of
my BIOS since I can use these Cylinders in the Linux O/S with ease.
Dos Fdisk will only recognize up to 128 megs of the 152 meg priam
MFM drive I have. Most IDE drives can have more than 1024 but they
trick dos and the Bios into thinking they only have 1024. I was
using a program called "Disk Manager V5" (nothing to do with Norton
Utilities) which loaded a driver into memory to access the rest of
the cylinders and do a "Fake" Fdisk. What I mean by that is it
kept the info on the partition in a file for it's own use. It
didn't actually access the partition on the Priam. Linux does but
the MsDos "FORMAT" won't even deal with a partition that goes past
the 1024 cylinders (Even if it IS there).
Microsoft and IBM won't acknowledge it's existence and I may want
to use this Hard Drive in Dos again sometime.
I'm currently using Dos 6.20 (probably the most undocumented Dos of
them all I would imagine.)
Sean Kearney
===============================================================================
4) CHOICE
I blundered onto an interesting choice.com feature:
CHOICE /C:XM*; /N /T:2,5
if errorlevel=4 goto help
if errorlevel=3 goto end
...etc
The "*" is the escape key, and the ";" is F1 etc.
Robert Lindsay
I can't reproduce the "feature".
Particularly, the * does not recognize the Esc key. All I get
is a beep. I'm using Choice.com from the DOS6SUPP archive
(though under DOS 5.0).
Later:
It occurred to me I hadn't tried an actual Esc character (ascii 27,
small left-pointing arrow). I did now, and it *does* work. You
have to use an editor that allows you to enter an Esc character
(most do, I think).
I couldn't get the ";" to be recognized as a function key though.
Gerry Pareja
The ";" is just part of the "ASCII code" for F1. F1 actually
gives an ASCII 000, to mark an extended key, and then the
semi-colon. CHOICE will beep at the 000, and then accept the
semi-colon.
Scott Wunsch
Since I am running DOS6, I shelled out when I read your msg and
created TEST.BAT, whose command line is exactly as:
CHOICE /C:XM*; /N /T:2,5
with the insertion of the little ^[ symbol (lp arrow) for the *
and F1 for the ;. When I executed TEST I got the following
feedback:
C:\PP\BW>CHOICE /C:XMF1 /N /T:2,5
CHOICE: Timeout default not in specified (or default) choices.
NOTE: Even tho the ^[ symbol does not show up, it was reconfirmed
to be in TEST.BAT.
Bat Lang
Here's a layman's attempt to throw some light on the matter:
The above syntax will produce an error because of the "/T:2,5",
but that's beside the point. My understanding of the above is
that CHOICE interprets the keyboard scan code as an ASCII code.
In other words, if the scan code for a particular key (or any
part of it) corresponds to an ASCII character which can be used
as an argument to the /C switch, then that key may be used with
CHOICE.
The second part of the scan code for F1 for instance is 59,
which is the ASCII code for a semicolon. Therefore "CHOICE /C:ABC;"
will accept either the semicolon key or the F1 key. If you press
F1 a beep will sound because of the first part of the scan code,
but the second part (59) is interpreted as a semicolon and is
accepted.
Another example: The code for "page down" is 81 which is the same
as a "Q", so if q is one of the arguments to the /C switch,
pressing "page down" will work as well (but with a preceding beep).
The ESC character (scan code 01) doesn't fit in with the above
theory, but works fine if represented by an ASCII 27 (left
pointing arrow).
Some ASCII equivalents to scan codes cannot be used with CHOICE.
F2 and F4 for instance, both require a redirection symbol, which
obviously can't work.
Another drawback is that if (like mine) the f-keys have been
allocated functions under DOS (via PROMPT), you get as many beeps
as there are characters allocated (until one of the characters
happens to coincide with one that CHOICE is expecting). My F12
key, for instance, gives me 10 seconds of beeps. :-)
Tested with MS-DOS 6.00.
John Evans
F1 is an extended key. It doesn't actually have an ASCII code, as
such, so the BIOS gives it an "ASCII code" of 0, or a null. After
it sends the null, it sends the scan code of the key, so that
programs can figure out which extended key it was. The scan code
for F1 is 59 (the ASCII code for a semi-colon). So you enter the
command:
CHOICE /N/C:;
CHOICE calls the BIOS and asks it to get it a key. You hit F1.
The BIOS sends the null (ASCII 0) to mark an extended key. CHOICE
doesn't like this and beeps. It goes back to the BIOS and asks for
another key. Now the BIOS hasn't finished with the F1. It sends
the semi-colon to tell CHOICE which extended key it was. Well,
CHOICE isn't smart enough to figure out that ASCII 0 means an
extended key, so it had just ignored it. Now it sees this
semi-colon, and decides it must be a perfectly valid key.
The function keys' "scan codes" are as follows:
F1: ; [059]
F2: < [060]
F3: = [061]
F4: > [062]
F5: ? [063]
F6: @ [064]
F7: A [065]
F8: B [066]
F9: C [067]
F10: D [068]
F11: … [133]
F12: † [134]
Obviously, you're not going to be able to use F2 or F4 in a batch
file :(.
Scott Wunsch
===============================================================================
5) COM or EXE
Also, have you noticed that 4DOS.COM (when viewed with LIST) begins
with the letters "MZ"? Isn't that the mark of a .EXE file? Very
interesting...
Thomas Smith
It sure is, and that's an example of something else that may be
a MUF. DOS doesn't care whether the extension on an executable
file is .COM or .EXE. It looks at the beginning of the file and
does the right thing according to what it finds.
Gary Smith
The identifier of an EXE file does not have to be MZ, ZM will
execute just fine too! (Other identifiers will not work however).
Jonas Oberg
===============================================================================
6) COMMAND, SHELL, and SYS
SHELL=C:\COMMAND.COM /E:1024 /F /P
COMMAND /F
The /F in your Config.sys SHELL= statement is another undocumented
feature.
It forces a "Fail" response to the "Abort, Retry, Fail" prompt issued
by the DOS critical error handler.
Dennis McCunney
What is the /F for in your SHELL statement? My DOS manuals make no
mention of an /F switch. It does mention that command line parameters
accepted by the command processor can be passed via the shell
statement. However, my DOS manuals make no mention of such a switch
for COMMAND.COM either. Was that a typo?
Gary Cooper
Nope, It's another undocumented feature. What I believe it is
supposed to do is force a "Fail" response to the "Abort, Retry, Fail"
message issued by the DOS critical error handler. I run 4DOS, so I've
had no occasion to actually test it.
Dennis Mccunney
The /F switch on the SHELL command in CONFIG.SYS will not work in
a DESQview environment. The only thing I have found that will is a
program called FATAL.COM.
Bruce Bowman
Makes all those annoying "Abort, Retry, Ignore, Fail?"
disk error messages default to "Fail".
Erik Ratcliffe
I thought this was well established as being available from v3.3
I certainly use it with MSDOSv5.0a and its been mentioned since my
early days in the echo back in Feb'93.
E.G.
@echo off
if %1.==. goto syntax
echo %comspec% /f /c copyprn$.bat>temp$$$$.bat
echo copy %1 prn: >copyprn$.bat
call temp$$$$.bat
if exist ???????$.bat del ???????$.bat >nul
goto end
:syntax
echo Usage: %0 [filename.ext]
echo Prints [filename.ext] if printer is ready.
echo If not terminates.
:end
I've posted this example usage myself - its handy if the printer is
the other side of a wall and you can't see if its ready.
Mark J. Allen
Yes, MS-DOS COMMAND.COM's "/F" parameter (default to Fail when
it cannot read a disk) works on all versions since MS-DOS v3.30.
Vernon Frazee
It certainly works with 3.3
Tom Coleman
I've used it (successfully) with M$ Dos 5.0, 6.0, 6.2. I will
retest, as well include some other versions of it. I figured
that someone had re-covered it by now, however I will send you
some NFO on it.
Steve Adams
I first used it with 5.0.....and have used it with 6.0 and 6.2.
John Mudge
I have just tested "command /f" in MSDOS 3.21 by booting from my
original (1988) floppy. It worked!! I booted from A: drive, typed
"ver" to confirm the version in use was MSDOS 3.21, typed command /f,
switched default drive to C:, then opened the floppy door on A: and
typed "dir A:". After a few seconds the Not ready reading Drive A:
message appeared, about 5 seconds later I was returned to the "C:"
prompt.
Pete Smith
I normally run DOS 3.31 on an old XT, but in Swedish translation.
It didn't work exactly as in your experiment. I wonder, if that
is because the alternatives are not Abort, Retry, Fail, but Avbryt,
F”rs”k igen, G† vidare. Ie the "F" option is the "retry" option.
Ragnar St Hle
Since the infamous DOS error message "Abort, Retry, Ignore?" didn't
become a more chilling "Abort, Retry, Ignore, Fail?" until DOS 3.3,
COMMAND.COM's undocumented "/F" parameter (default to Fail) probably
wouldn't have been discovered, if it existed, in earlier releases.
Vernon Frazee
Microsoft(R) MS-DOS(R) Version 3.20
(C)Copyright Microsoft Corp 1981-1986
A>c:\u2\ssxtra 5000 /q
A>command /f
Microsoft(R) MS-DOS(R) Version 3.20
(C)Copyright Microsoft Corp 1981-1986
A>dir b:
Not ready error reading drive B
Abort, Retry, Ignore? Volume in drive B has no label
Not ready error reading drive B
Abort, Retry, Ignore?
Not ready error reading drive B
Abort, Retry, Ignore? Invalid drive specification
A>
My first computer was a Commodore XT clone with MS-DOS 3.2.
I was using the /f switch then, and remember experiencing the
same 30 second delay. I just booted up my 386 with v3.2 and
tried the same thing. The delay was less than a second.
Evidently, the delay factor depends more on hardware (and
maybe BIOS) than the DOS version.
David Adamson
I just shelled to invoke a COMMAND from a 2.0 floppy
and it crashed my server!
Tue 5-13-2* 8:16:08*A:\>c:\u2\ssxtra 5000
*NOT* residentústatus=ONúmode=ANYútimer=3úINSTALLEDú
(5000) buffer size requested, Available: (5014)
Tue 5-13-2* 8:16:15*A:\>command /f
Command v. 2.11
Tue 5-13-2* 8:16:27*A:\>dir b:
Not ready error reading drive B
Abort, Retry, Ignore? f
Abort, Retry, Ignore? f
Abort, Retry, Ignore?
(Captured/written-to-disk _at_ the Crit-Err prompt via SSXTRA
((fwiw I also command /F,a,A,i, and I with identical results))
(((All DOS's "R"etry minimum 3 times before -> crit-err)))
then....
Microsoft(R) MS-DOS(R) Version 3.20
(C)Copyright Microsoft Corp 1981-1986
A>c:\u2\ssxtra 5000 /q
A>command /f
Microsoft(R) MS-DOS(R) Version 3.20
(C)Copyright Microsoft Corp 1981-1986
A>dir b:
Not ready error reading drive B
Abort, Retry, Ignore? Volume in drive B has no label
Not ready error reading drive B
Abort, Retry, Ignore?
Not ready error reading drive B
Abort, Retry, Ignore? Invalid drive specification
A>
w/ No intervention on my part at all, although it took over
30" to get back to the prompt. So "/f" processing *is* present,
if very shoddily implemented, in MS's 3.2. (which is also
pretty darn buggy otherwise)
Don Hoffman
YES "command /f" does work on MS-DOS 3.21.
Pete Smith
COMMAND /P
Docs say that this doesn't allow you to exit back to the
previous shell (ie /Permanent), but /P also forces
\autoexec.bat to be run on secondary shells.
COMMAND /D
(When used with a primary shell, or secondary with /P)
prevents execution of \autoexec.bat
Mitch Ames
I just checked, and these also both apply to DOS 5.00
Mitch Ames
COMMAND /E:
...remember the constantly returning thread of getting secondary
shells' environments greater than 256 bytes? Well I had cause to
mess around on someone's machine and needed a larger secondary
shell from a pgm that didn't allow shell definition when it dawned
on me that you can just modify the COMSPEC variable to include the
trailing /e:#### and as most well behaved pgms use the comspec
variable this works wonderfully!
Mark J. Allen
I've never tried that. I thought I read someone here did that and
it wasn't accepted by the program, but it sounds like an excellent
solution.
Rob Flor
Well, I had the same idea some time ago, but I can't report the
same success as you had. :-( I experienced the whole range of
inexplicable errors, crashed programs, system hangups, etc.
Seeing as /E is a valid parameter for COMMAND.COM, It must be
something to do with the (faulty?) way certain programmes
handle the comspec variable.
John Evans
I tried it for a day or so the last time the "how to increase the
environment" went round.
May just be my choices in s/w, but I didn't find a single pgm that
was able to shell successfully via the adulterated comspec.
Don Hoffman
Or you could do:
COMMAND.COM /E:5000 /C C:\YOURAPP.BAT
Single line, decrease/increase the environment as needed. No SET's
needed.
And as far as I can tell, it works just great under DOS5.0, when
running DESQview, I run multiple windows, and am running a VBBS
multinode system. When I shell out to DOS(in that window), the
batch files I have running will not function if I DON'T change
the /E: size, and in most cases lock up the system.
However, I have never had a problem since using the above statement.
What it is doing I can not say, but it sure works here!
Tony Talarigo
SHELL=COMMAND.COM /NUL
Adding a "/NUL" to the SHELL= statement in CONFIG.SYS will remove
the possibility of a user being able to use [Ctrl-C]. Example:
SHELL=C:\DOS\COMMAND.COM C:\DOS /E:1024 /NUL /P
Vernon Frazee
SHELL=C:\COMMAND.COM C:\ /p
~~~
The second parameter tells the OS where to find the command processor
when the transient code is overwritten. In addition, the inclusion of
this parameter in the SHELL statement will automatically put the
COMSPEC environment variable in the environment for you.
Robert Clark
The word on my block is that the second parameter is simply wasted
typing (read: redundant), UNLESS the CP is not in the root (as it is
above). Accordingly my shell line has never included it, yet when I
enter SET at DOS, I always see as the first environment variable, the
COMSPEC line. Could this be a MUF? Just a hold over from some earlier
versions of DOS? I am using 6.2, but cannot remember using that second
parameter, since the word went around {^; (I may have read that from
either Dan Gookin or DOS Power Tools).
Bat Lang
It was introduced with DOS 4, which needed SHARE to support
large media (40meg HD). If SHARE wasn't loaded in config.sys,
DOS used the second parameter to find SHARE.EXE, not COMMAND.COM.
If command.com is in the root, you don't even need a shell or explicit
comspec statement.
Rob Flor
NO COMMAND.COM IN ROOT DIRECTORY
MS-DOS doesn't use a specific location any more (for system
files). You can move'm around all you want. At least since
DOS 5.
Dos 5+ system files aren't position sensitive. Just replace
dos 5 with dos 6 including command.com and system files,
then reboot the machine.
Try it yourself. Format a floppy with dos 5, copy new
system/command.com to it, and reboot.
Rob Flor
In the absence of a SHELL statement, MS-DOS v6.x looks for the CP
(command processor) first in the \DOS directory, then in the root,
then in \MSDOS. The COMSPEC evar will then be set to wherever the
CP was found.
Robert Clark
The three subdirectories, "\", "\DOS", and "\MSDOS" can be seen
inside DOS's hidden "IO.SYS" file and, DOS automatically sets the
COMSPEC environment variable to point to the location of the
COMMAND.COM it booted with.
Vernon Frazee
Is this search pattern documented anywhere that you have seen?
Gary Cooper
Not officially, at least not that I'm aware of. Someone over in
the RIME DOS conference mentioned this over a year ago, and a
little experimentation at the office showed that the search
pattern worked as advertised.
I'm just showing my (operating system) age. In the absence of
a SHELL statement, MS-DOS v6.x looks for the CP (command
processor) first in the \DOS directory, then in the root, then
in \MSDOS. The COMSPEC evar will then be set to wherever the CP
was found.
Previous versions would choke and die horribly if the CP weren't
in the root and there was no SHELL directive. Also, the COMSPEC
would only be created if the second parameter in the statement
SHELL=\foo\path\foo.bar \foo\path\... was present.
^^^^^^^^^^
In the absence of a SHELL statement, MS-DOS v6.x looks for the
CP first in the \DOS directory, then in the root, then in
\MSDOS. The COMSPEC evar will then be set to wherever the CP
was found.
Robert Clark
DR-DOS 6 doesn't care where it's corresponding files (IBMBIOS.COM,
IBMDOS.COM) are physically located, so long as they are in the root
directory. In fact, I have sometimes run ATTRIB -RH on them so that
a HD defrag program would move them.
Tom Schluter
The same is true of MS-DOS, versions 5.0 and later.
Gary Smith
Yes, happens here too (DOS 5.00). Even more annoying is that the
expen$ive Norton Utilities will get fooled too. You can't "Make a
diskette bootable" unless COMMAND.COM is on the root of C:\
regardless of the value of COMSPEC.
Gerry Pareja
? ... working here:
a) Running MSDOS v5.00 revA
b) SHELL=C:\DOS\COMMAND.COM
c) COMSPEC=C:\DOS\COMMAND.COM
d) and _no_ COMMAND.COM in the root dir
A subsequent:
FORMAT A: /Q /U /S /V:"" /F:1.2
command produces a bootable 1.2meg floppy
(with IO.SYS, MSDOS.SYS, and COMMAND.COM).
Vernon Frazee
Yes the above works, what doesn't work is:
SYS C: A:
You get the message "Could not copy COMMAND.COM onto target disk",
you can of course copy COMMAND.COM to the target disk manually.
The same is true in Dos 6.00 and 6.20, except DBLSPACE.BIN also
gets copied over as a system file.
So FORMAT is able to use comspec to find COMMAND.COM, but the SYS
command is not.
Terry Kreft
The only problem seems to me that doing SYS A: will come up with the
message "Could not copy COMMAND.COM onto target disk" (and what you
have to do then is obvious).
John Gray
My SHELL command has always pointed to my MSDOS directory, but
I've always had a copy of COMMAND.COM in the root (I think
INSTALL puts it there). I've just deleted it on two machines
(one with 6.00 German and one with 6.20 English) and, sure
enough, the SYS command couldn't find it on either machine.
Up until now I've always believed my big thick DOS 6.00 bible,
which clearly states that the SYS command will search for
COMMAND.COM in the path specified by the COMSPEC variable...
John Evans
I'm using NDOS and I don't have COMMAND.COM (or NDOS.COM for that
matter) in the root directory and I just formatted a diskette to
be bootable using SFORMAT.
Scott Paterson
C:\dir a: /a +- Now what's on A:
|
Volume in drive A has no label |
Volume Serial Number is 4029-12F7 |
Directory of A:\ |
|
DBLSPACE BIN 64,246 09-30-93 6:20a +- No COMMAND.COM!
IO SYS 40,566 09-30-93 6:20a | Also I don't have
MSDOS SYS 38,138 09-30-93 6:20a | DBLSPACE.BIN in my
3 file(s) 142,950 bytes | root. So it managed
1,313,792 bytes free | to find that.
|
C:\ +- Done
Note this is with MSDos 6.20!
Wonder why SYS doesn't work "properly" (i.e. doesn't use COMSPEC
to find COMMAND.COM) if they fixed it for the version your using
on that set-up.
Aha, I got my MSDos 5.00 disk working and SYSed my HD to 5.00,
deleted COMMAND.COM from root and SYSed a floppy (using MSDos
5.00 SYS.COM) and it copied COMMAND.COM over, so for some reason
they've taken the facility (to use COMSPEC to find COMMAND.COM)
out!
Terry Kreft
===============================================================================
7) COPY
Using:
COPY <wildcard specifier> <explicit filename>
is the same thing as:
FOR %%1 IN (<wildcard specifier>) DO COPY <exp. filename>+%%1 <exp. filename>
such as:
COPY *.TXT ALLTEXT.DOC
is the same as:
FOR %%1 IN <*.TXT> DO COPY ALLTEXT.DOC+%%1 ALLTEXT.DOC
I used this one to combine all the MUF files to one file by saying
copy *.txt muftext.doc
any wildcard specs and exp. filename will work just fine...
Mike Anderson
Try:
COPY FIRST+SECOND FIRST
Whatever happens, it is a DOS requirement that you have to create
a completely new file, with both sets of records in it -- this is
just how ordinary DOS files work, I'm afraid, so you're stuck
with it.
John Gray
Unless you do this one:
TYPE SECOND >> FIRST
However, if FIRST has an EOF mark, it will probably not be removed
with old M$-DOS versions (my M$-DOS 5.0 works fine though).
Horst Schaeffer
Well, would you believe it! You seem to have found an exception to
my 'rule'! Well done...
John Gray
You can do:
COPY FIRST+SECOND
with the same results. (The SECOND file concatenates to the
FIRST).
Vernon Frazee
This is true -- yet another undocumented feature?
John Gray
Command.Com won't copy a zero-length file; 4DOS will - thus breaking
all those bat files which use this "feature".
Mitch Ames
Actually, I thought this was a problem in some of the newer (5.0+?)
versions of DOS.
Scott Wunsch
I believe this "feature" has been around since at least v3.30, and it
is documented in v5.0 (p391 of the manual).
I just checked and v3.30 of command.com can't copy 0 length files
either, but it is _not_ documented in the 3.30 (MS-DOS) manual.
Mitch Ames
(EDITOR'S NOTE: See the DIR and DELIMITING CHARACTERS sections as well
for additional information on the use of . , .. \ etc. as below)
I acknowledge that some of the information presented in these sections
may be documented, although obscure features. The reason that this
information continues to be seen in the MUF list is because I believe
that the ability to use the period immediately after the copy command
IE: COPY. is not documented. What is documented is the fact that "."
and ".." can be used to represent the current and parent directories
respectively, and these will work with many applications which can
handle directory names as arguments. In this case the "." could also
be viewed as a replacement for "*.*"
COPY. A:
The use of a decimal point IMMEDIATELY after some DOS statements,
will replace *.*
EXAMPLES: DEL. (erase all files in current directory)
COPY. A: (copy all files in current directory to A:)
There may be more statements with which it works, but I haven't
tried them yet.
Willem van den Broek
"." means the current directory, and Command.com will assume that
\directory implies \directory\*.* for most commands where a
filename(s) should be specified, eg:
DIR \ is the same as DIR \*.*
COPY \FRED is the same as COPY \FRED\*.*
COPY. A:\ is the same as COPY .\*.* A:\ which is the same as COPY *.* A:\
DEL. is the same as DEL .\*.* which is the same as DEL *.*
Mitch Ames
===============================================================================
8) CTTY
EDITOR'S NOTE:
The following section consists of extracts from messages which have
answered the question: "How do I stop the program output (during the
loading of CONFIG.SYS) from being echo'd to my screen". Many have
suggested that users redirect the output to the NUL device, however,
this technique has been found to cause errors when the program being
loaded is a TSR (Terminate and Stay Resident). The errors are due
to the fact that the TSR does not release the file handle which is
used in the redirection process.
The reason I started using ctty was because of a message in a
echo which I now forget, maybe debug. Some guy was having a
problem to which he got the response that too many program >
nul used up "handles".
Dan Dunfee
There's a thread going on here now about redirection not releasing
file handles when you re-direct output from a TSR. I don't think
its a problem otherwise, didn't know it was a problem with TSR's.
Jack Stein
FYI, the same thing happens (trapped file handles) when you CTTY>NUL
and load a TSR.
Gary Cooper
That would be the heading in my DOS manual (CTTY) where I
would "expect" to find warnings about redirecting TSRs...
but mine doesn't even acknowledge that "nul" _is_ a valid value
for CTTY (although I've been using it to hide stuff since 2.0,
and my 670 page manual _does_ list "prn, lpt1-3, con, aux, and
com1-4" as valid devices to ctty to.)
AH HA! Now it *is* a MUF!
"CTTY NUL" is *UN*documented and WILL WASTE a file handle if used
in conjunction with loading a TSR. The same will happen if you
"redirect" a TSR to nul.
Don Hoffman
In the FWIW department I had to test/verify the CTTY thing for
myself (just now,) and I found something slightly interesting in
that the 'releaser' pgm:
FILES - (c) 1993 Holger Daehre 2:248/317.88
which BERND HOHMANN kindly posted here was _not_ able to recover
all the handles I trashed via: .bat file:
ctty nul
fmark %tmp%test.mrk
eatmem 1
eatmem 1
eatmem 1
eatmem 1
ctty con
It initially showed 2 handles lost and unrecoverable; When
I RELEASEd /K(ept mark) it still showed 2 gone/unrecoverable...
but after a second RELEASE (of test.mrk too) it reported 1 file
handle reclaimed, and one still lost.
A second run w/ the EATMEMs commented-out lost me another
handle which couldn't be recovered regardless of RELEASEs done.
(I even released all the way back to my '00' mark, which kills
everything except my command processor... 2 extra handles still
reported as in-use / unrecoverable):
Number of used handles before cleaning : 006
Number of used handles after cleaning : 006
(should be 4 at this point, including the redirection for capture,
but note I do _not_ have any alternate technique to verify /
crosscheck these numbers with!)
I expect 'your milage may vary'... maybe something about
my (ancient 8088 semi-compat) hardware, and/or software platform
(IBM 2.0.11 + MS 5.0 + 4DOS)... or maybe even pgm bug. (Those
results don't make a lot of sense to me... but it's hardly
something I should be doing in the first place ;-))
Don Hoffman
EDITOR'S NOTE:
In response to a question asking why:
MD C:TEMP > NUL
did not work as expected...
If C:\TEMP already exists, MS-DOS 6.2 will STILL REPORT that fact,
even with the " > NUL" output redirect. If the original poster
needed a completely silent process, this won't quite do it.
Steve Burton
True, however CTTY NUL before the md command, and CTTY CON after
still works, eg:
ctty nul
md c:\temp
copy a:\*.* c:\temp
ctty con
Unfortunately, CTTY >NUL no longer works, at least in Dos 6.2
Dale Woloshin
===============================================================================
9) DELIMITING CHARACTERS
Prior to DOS 5.0, there was an undocumented DOS function that
would allow you to set the DOS option delimiting character to
something else, like -. Once you did this, you could use either
\ *or* / in PATH specs.
DOS 5.0 removed the function to *set* the option delimiter, but
*retained* the one to query what it currently is! (Don't ask me,
ask M'Soft...) Fortunately, the MKS Toolkit still works with no
apparent glitches.
I believe in pre-DOS 3.X versions that there was a parm you could
provide in CONFIG.SYS to do this, but have no further details.
Just remember: "undocumented" is a synonym for "unsupported, and
not guaranteed to be there next release", which is what happened
in the case I mentioned above.
Dennis Mccunney
Another good thing is you can travel from directories to
directories without typing "CD". Just type the directory name
followed by a backslash '\'.
Example: To go from C:\BATCH to C:\WP51, you type "\wp51\".
That's it! fast and easy.
Marc Y. Paulin
This is a 4DOS/NDOS feature; it is not available under COMMAND.COM.
Scott Wunsch
If you are in the following directory :
\WORD\FILES\LETTERS\APRIL
And wanted to go to the directory \WORD\FILES, you'd normally
type two lines :
CD \
CD WORD\FILES
Or even the single line "CD \WORD\FILES" to combine the two
commands into one. There is a shorter way, simply type the
following : CD ..\.. You're there!
Andrew Barnhardt
I just found out that using the command
DELTREE .
cause the deletion of all directories with verification,
ie 'do you want to delete the directory somedir and all
subdirectories and files?'. If you've got 6 directories
in the directory your in you get prompted for each one.
Kirt Thomas
While the on-line help does not specifically mention using the
dot "." character, it does have a section stating that you can
use wildcards. I consider the dot to be a wildcard.
It says that if you use a wildcard, any matching files and
directories will be deleted.
Michael Clays
EDITOR'S NOTE: For additional information regarding the use of
"." as a wildcard see the DIR section.
Have you tried the subject line? i.e. DELTREE /Y C:\TEMP\
(note the trailing backslash)
With MSDOS 6.22 it will delete all files in, and all subdirectories
below, but will NOT delete \TEMP itself!
Michael Marquart
I get two empty directories in each directory, too. (called"." and
"..") Maybe because mine are 4096-bytes?
Bob Browar
Every directory you create off of the root directory will contain a
"." (single dot) and a ".." (double dots).
The single-dot is an abbreviation for the current directory and
the double-dot is an abbreviation for the next directory up (parent)
The single-dot is really pretty useless as far as when using it with
one of the directory commands: MD (make directory), CD (change
directory), or RD (remove directory). But, it can be used to do
something like:
a) Copy everything in your current directory to A:\
copy . a:\
b) Create a zero-length file:
cd.>x
(file "x" will be a zero-byte file)
d) Even handier but possibly disastrous, the following command
will not only delete all the directories of, but of all the
files (even the ones with the Hidden, System, and Read-Only
attributes assigned) in and below, your current directory:
deltree /y .
For example, if you had the directory structure:
A:.
\---TEST
+---1
+---2
+---3
+---4
\---5
had files (even hidden) in any or all of the directories, and
you were in the root directory of drive A:, the command:
deltree /y .
would delete _everything_ below the "." (current) directory.
The double-dot ("..") directory entry comes in handy when you want
to change to a sister directory. For example, take the same
directory structure:
A:.
\---TEST
+---1
+---2
+---3
+---4
\---5
Then let's say you're in directory "A:\TEST\3" and want to change to
"A:\TEST\5". Instead of typing:
cd\test
cd 5
or:
cd\test\5
you could just type:
cd ..\5
(Remember, the ".." stands for the next directory up (the parent)).
Let's say you were in "A:\TEST" and wanted to copy everything in it
to the root directory:
copy . ..
(In other words, copy "current-directory" to "parent-directory").
If you wanted to copy everything from the root to where you were:
copy ..
This is but a _small_ example of how the single- and double-dot
directory entries can come in handy with a variety of commands.
Vernon Frazee
===============================================================================
10) DEVICEHIGH
This line in CONFIG.SYS will, according to MS-DOS 6.22 help,
prompt the user about loading the device with the classic [Y,N]
DEVICEHIGH? /L:1,9072 =C:\DOS\ANSI.SYS
And so it did for me until I ventured into multiconfig to
accommodate some EMS demanding proggies.
It appears that once the [MENU] is added to CONFIG.SYS this is
no longer an option. Not a major hassle, as a submenu can be
used as a work around, but I was unable to locate any mention
of this drawback in the HELP.
Peter Lovell
===============================================================================
11) DIR
DIR (, . ...)
DIR,
Using a comma IMMEDIATELY after DIR, shows ALL files, including
the HIDDEN ones.
EXAMPLE: DIR,
Willem van den Broek
EDITOR'S NOTE: As you will read below, there are mixed reports as
to whether this MUF will work the same with all versions of DOS.
Warning: Your "mileage may vary". Much of what is reported in this
section might also have been covered in the Delimiting Characters
section.
Just tried it here, booting off of an original MS-DOS 3.30
diskette, and what Mr. Broek stated is true.
Vernon Frazee
Going back as far as DOS 3.3, it is possible to find hidden
files, and hidden directories for that matter by using the
following:
DIR,
It seems a bit easier than testing for attributes. It simply
show all files in the required directory
Greg Miskelly
This appears only to work with version 5. I tried it with 3.30,
and it didn't display either IO.SYS, MSDOS.SYS (both with S, H
and R attribs) or a test file with A and H attribs.
With version 5 it displayed the test file with H and A, but would
not display IO.SYS or MSDOS.SYS with S, H and R. This doesn't
surprise me actually, since S alone (without H) will prevent
inclusion of a file in a normal DIR.
I didn't try version 4.
Mitch Ames
I can confirm that the DIR, does NOT work with MS-DOS 3.2, 3.3,
and 4.01, nor with Compaq DOS 3.31, DR-DOS 6.0, or Novell DOS 7.
Works here with MS-DOS 5.0, MS-DOS 6.0, and MS-DOS 6.22.
Ron Warder
It also works as DIR , (with an intervening blank).
John Gray
MS-DOS Version 5.00
C:\ >dir ,
Volume in drive C has no label
Volume Serial Number is 1221-0000
Directory of C:\
IO.SYS
MSDOS.SYS
[BATCH]
* * *
WINA20.386
36 file(s) 508790 bytes
35735552 bytes free
MS-DOS Version 5.00
C:\ >attrib io.sys
SH C:\IO.SYS
As you can see, this system's using MS-DOS 5.0, IO.SYS is
System and Hidden, and "Dir ," displayed both it and MSDOS.SYS.
Bruce Wilson
It works here with PC-DOS 6.1
Rodney Foremski
I dug out my old disks and rebooted to try each version with the
following results:
MS-DOS Version 3.21 12-03-87 3:21a
IBM Personal Computer DOS Version 3.30 3-17-87 12:00p
dir, - does not show hidden files in either version,
- the original manual I received with V3.21 only
lists the +/- A and +/- R options for the ATTRIB
command, no mention of the ability to set or
modify the System or Hidden attributes.
- any attempt to set or unset the System or Hidden
attributes on a file using ATTRIB under these DOS
versions results in a "Syntax error" message.
MS-DOS Version 5.00 04-09-91 5:00a
dir, - displays all files in the current directory regardless
of attributes set (Archive,System,Hidden,Read only)
- online help and manuals fully document the ATTRIB
command's ability to set/unset all attributes.
Those are the only DOS versions I have handy, hope this helps.
Pete Smith
Interesting: it (DIR,) does for me (display DOS5 IO.SYS and MSDOS.SYS):
However, 4DOS does not do it:
Dennis Mccunney
It was pointed out in the 4DOS echo, and there were people
who said it didn't work for them. But, on my machine running
straight dos6, it works! DIR, (dir comma) in my C:\ shows all
files including hidden and system.
Bill George
EDITOR'S NOTE: In response to the following comment:
If you include the /b switch, you'll get the complete
pathname for each file. Also if you use the forward slash
you'll get all the dll files on the current drive.
dir/s/b \*.dll|sort>dll.txt
Jeff Martin
EDITOR'S NOTE: Jeff receive the response:
You will, UNLESS you happen to HIDE a directory or two (or three)!
This command will NOT report ANY files that are inside a hidden
directory tree.
I played with this a bit, but didn't find a way to include hidden
dirs and/or hidden files with a "simple" command.
Gary Smith
There is an undocumented variation.
dir,
that will include system and hidden directories/files. The comma
needs to be right after the r.
Roger Scudder
No, actually it doesn't...try "DIR ," or even "DIR/P ," and
it still works, *but* you canNOT (as far as I can tell) use the
"comma MUF" when you SPECIFY a target, ie the *.DLL in the original
example.
dir/s/b \*.dll|sort>dll.txt
Greg Smith
DIR..
With DOS 6.0 you can get a directory of -all- files (hidden,
system, etc.) with this command.
It was in a PC/Mag. or PC/Comp. issue not too long ago.
Andrew Barnhardt
DIR...
Have you noticed also how DIR ... only displays directories, not
files?
Gary Marden
That's pretty slick. I tried DIR.. and got the parent
directory. DIR... got the current directory subdirs only.
Bill George
Works for any level of directories. ".." will go to the previous
directory as with pure DOS, "..." will go to the directory before
the previous and so on.
Ng Cheng Kiang
In DOS 5.0, it displays files and directories which have no extension.
Larry Kessler
Here's another gem discovered here for DIR, try DIR...
shows only subdirs.
Richard Gray
In DOS 5.0 it displays directories and files with no extensions.
I tried "DIR ...", "DIR...", and "DIR ....". They all behave
the same way.
Gary Smith
With DOS 5.0 and NDOS 6.0, DIR... gives me a list of
subdirectories off of the root and a list of all files in
the root directory, regardless of the file extension. It
will yield this result regardless of what directory or
subdirectory I am in at the time the command is issued.
Gary Cooper
This is, I believe, a result of another little feature (MUF?),
that allows DIR to accept an extension like this: "DIR .BAT".
This would act like "DIR *.BAT". Because DOS automatically
trims off useless characters, it trims the "..." down to a ".",
but doesn't process it as meaning the current directory because
it is already past that part of its processing.
This is because 4DOS/NDOS can handle ... as the "parent of
the parent directory". So if you were more than three
directories deep, then DIR... would no longer give you the
root.
Scott Wunsch
COMMAND.COM generally seems to ignore excess characters. Try
copying something the AIRPLANES.PLAN, for example, and see what
happens.
Gary Smith
While I was playing around with "dir ..." and trying to see
how it parses to showing all extensionless entities in the
current directory, I noticed that DIR doesn't care if a
specified directory structure exists or not, as long as the
overall structure points back to something that does exist, i.e.
dir \thisdirdoesnotexist\..
will ignore the garbage and show the root directory. If
c:\bat exists, then
dir c:\bat\thisdirdoesnotexist\nordoesthisone\..\..
will show the c:\bat directory.
Again, absolutely useless as far as i can tell <g>, but
interesting.
BTW, has anybody solved the "dir ..." mystery yet? I also
noticed "dir \..." works while "dir \bat\..." fails (any
explicitly specified directory other than the root generates
an "invalid directory" message).
Paul Leonard
Regarding the 'point' notation/wildcarding, the situation
is that "point-notation" is recognized at the INTERRUPT-level
by some DOSs/some interrupts. It is *not* a MUF in the sense
(A) that it *is* documented in any comprehensive Int Reference
Manual; (B) it is *not* specifically "available" to/from certain
DOS (etc) commands, it is rather "passed-on" without syntaxing
(maybe) to the BIOS-level functions, which may or may-not
recognize it, dependant on what OEM and HARDWARE you have, and
is relatively *IN*dependant of whatever DOS you are currently
running.
In Other Words: it's a documented Freebe/Maybe --- at the
BIOS/INTERRUPT level!
nb. Anywhere single-dot notation (current directory) is
accepted/works, so will double-dot '..' (and maybe triple-dot,
etc!!) This is a _very_ good way to accidentally *trash* your
ROOT directory!!
'..' => "parent of current directory"
'...'=> "parent of parent of current directory", etc; although
in some implementations a '\' may be needed following
the last '.'
I think the CD question ("CD\" as opposed to the documented
"CD \") is in the same category: it is not-even an MS
*Function* per se, but is rather 'recognizable' by the BIOS
functions which the Command-Parser relies upon.
Don Hoffman
DIR *.
To be exact: this (DIR...) shows all files and directories without
extension, just like DIR *.
(tested under MS-DOS 5.0)
Horst Schaeffer
You are right! I am surprised.
DIR *. will list directories, but no files!
Per Kristensen
This one doesn't only show subdirs, it also shows files
without extension.
Rene Verhagen
If the directory is empty, the above will fail.
Vernon Frazee
===============================================================================
12) DRIVPARM
DRIVPARM /c
Syntax: DRIVPARM /d:number [/c] [/f:factor] [/h:heads] [/i] [/n]
[/s:sectors] [/t:tracks]
/d:n refers to the drive NUMBER (0=A:, 1=B:, 2=C:, etc...) of the drive
whose parameters you are changing (in your case, it would be 2 for
B:).
/c is the switch I was referring to for change line support. IF YOU
INCLUDE /c, YOU ARE TELLING DOS THAT YOUR COMPUTER *CAN* TELL
WHETHER THE DRIVE DOOR HAS BEEN OPENED SINCE THE LAST ACCESS.
/i specifies an electronically-compatible 3.5 inch floppy disk-drive.
You should use it if your computer's ROM BIOS does NOT support 3.5
floppy diskette drives.
/n specifies a NON-removable block device
The other parms are similar to DRIVER.SYS
IBM Technical Publication Information
forwarded by Andrew Barnhardt
The '/C' switch doesn't actually check to see if the drive -door-
has been opened or not, but it does make another check to see if
the disk in there now is different from the one when the drive was
last accessed. I have to use that switch with my 5 1/4 floppy
because it's an older drive working with a new motherboard (at
least that's the explanation I've heard).
Andrew Barnhardt
Does DRIVPARM return an errorlevel, or give a warning message?
Gary Cooper
No, not that I'm aware of. You insert the drivparm command in
your CONFIG.SYS file. Just DRIVPARM=xx xx ...
Andrew Barnhardt
===============================================================================
13) ECHO
ECHO OFF from the command line erases the prompt and leaves
just a cursor on the screen.
ECHO ON from the command line restores the prompt.
This works with all version of DOS (tested so far!).
Michael Larsson
EDITOR'S NOTE: One of the most frequently asked questions in
the BatPower echo is "How do I ECHO a blank line?" The most common
answer is "ECHO." However, I have captured a few posts which
expand on the possible answers to this request:
ECHO"
Paul Welsh
just about any white space character will work.
Alan Newbery
I just found out myself that any delimiter will work here
(ECHO. ECHO" ECHO, ECHO: ECHO; ECHO[ ECHO] etc.). Apparently
it's just the way that the command handles the delimiter and
has been available from way back. Microsoft just began
mentioning it in the documentation recently, though, and their
examples use a period.
John Whitfield
Different sets of delimiters work in different versions of DOS.
Finding one that works in all versions can be tricky, but if I
recall correctly, the period works most of the time.
Gary Smith
Can anyone tell me how to write
OFF
on the screen - with no preceding spaces, no quotation-marks etc.
from a batchfile - and preferable with the ECHO-command?
Karsten Weldingh
Simple, try:
ECHO.OFF
Works fine under DOS 6.0!
Michael Larsson / Matthew Lewis
DOS 5.0, too - where did you find this tidbit? I just tried it with
the usual suspects and they work, as well (echo[off, echo]off, etc.).
Paul Leonard
EDITOR'S NOTE: Regarding the commonly used technique of using:
ECHO.|TIME
to feed a carriage return / line feed to the MS-DOS TIME command,
and avoid the necessity of pressing ENTER in response to the TIME
commands' prompt to enter a new time, I captured the following
discussion:
Just a note, the command:
VER|TIME
will prove to be a bit faster.
Since both are internal commands the elapsed time
required for each to execute should prove to be almost
identical. We quit using the "echo." about a year or so
ago when because of a blurb in PC World (or was it PC
Magazine) that said it would reset the time to 00:00 on
one of the popular brands of network software.
Vernon Frazee
"echo. |time" is faster yet, and is abusive of neither DOS nor
the user.
That would qualify as a bug. I don't think much of introducing
buggy "work arounds" for something that NEEDS to be fixed.
("VER|TIME" will hardlock some CLI's, depending on the format
VER is presented in... neat: crash a time-check because of an
unusual VER format.)
Don Hoffman
What brand of network software, what CLI's?
Gary Cooper
I do know from personal experience that VER | TIME _will_
hardlock some non-MS's however... 4DOS 4.0 rev B for-sure.
Don Hoffman
echo "echo y|del *.* > wipe.bat" > test.bat
will create the file test.bat but it contains the line
"echo y|del *.* > wipe.bat"
which of course will not execute. All you have to do is find a way
to delete the double quotes, an intellectual exercise :-) If you
find an answer I would appreciate knowing as well.
Amer Neely
You can use EDLIN to strip the quotation marks out of TEST.BAT
with:
C:\DOS\EDLIN TEST.BAT < TEST.SCR
Where TEST.SCR contains the following:
1,#r"^Z
e
You will have to create TEST.SCR with an editor which permits you
to put a ^Z directly into the document. This is NOT a caret and
an upper case "Z", with EDLIN it is F6 or ASCII-26 the end of file
marker. For example, in MS-DOS EDIT you can place the ASCII-26
character (a small right pointing arrow) in a document by pressing
CTRL-P and then CTRL-Z.
Gary Cooper
To eliminate the leading double-quote you can do a:
echo"echo y|del *.*>wipe.bat ">doit.bat
(Note how the two echo's are separated by a single double-quote
mark with no space). When the above is executed, DOIT.BAT will
contain:
echo y|del *.*>wipe.bat "
In this particular instance the trailing double-quote mark doesn't
really matter (because it is separated by a space from the file
extension). But, if it really bothers you, it can be eliminated
using EDLIN _without_ worrying about a ^Z ([Ctrl-Z]). Try this:
@echo off
echo"echo y|del *.*>wipe.bat ">doit.bat
for %%x in (echo type) do %%x DOIT.BAT
echo 1,1r">temptemp.scr
echo e>>temptemp.scr
echo.
echo EDLIN at work:
edlin doit.bat<temptemp.scr
echo.
for %%x in (doit.bak temptemp.scr) do del %%x
for %%x in (echo type del) do %%x DOIT.BAT
Hint: The only time you need a [Ctrl-Z] with an EDLIN "R" (replace)
command is to separate the character(s) being replaced from
the character(s) they are being replaced with.
Vernon Frazee
===============================================================================
14) EDLIN
where an EDLIN script is:
-1,#r 1:^Z 1:
-1,#r 2:^Z 2:
-1,#r 3:^Z 3:
-1,#r 4:^Z 4:
-1,#r 5:^Z 5:
-1,#r 6:^Z 6:
-1,#r 7:^Z 7:
-1,#r 8:^Z 8:
-1,#r 9:^Z 9:
e
Note the spaces (one after R, two after ^Z) which prevent replacement
of the second digit in a two digit number.
This will update the last line only, so needs to be done at each
boot. '#' means last line +1. '-1' means the line before the current
one (ie: the last line of the file, if "#" is the current line). Note
that you can only use '-1' in later versions (it works in 5, but not
in 3.30 as far as I know).
Mitch Ames
In Edlin 3.30 and 5.0 you can use the following as line numbers:
. current line
-n n lines back from the current line
+n n lines forward from the current line
# end of the file
'.' and '#' were documented in 3.30, but aren't in 5. -n and +n are
not documented in either.
Mitch Ames
Your 3.3 manual is obviously different than mine. All of the above
are documented in "Microsoft MS-DOS User's Guide and User's Reference"
which was published by Microsoft Corporation, 16011 NE 36th Way,
Redmond, WA 98073-9717 in 1987.
Edlin is covered on pages 161 to 193.
John Evans
Correction:
John Evans pointed out that -n and +n _are_ documented in v 3.30
(under "tips for using Edlin"). There is also a single reference to
+n in the 5.0 manual under the Move command (line1,+n,line3 M), but
it does not say that you can use +n anywhere else.
So I guess the MUF should read:
In Edlin 3.30 and 5.0 you can use the following as line numbers:
. current line
-n n lines back from the current line
+n n lines forward from the current line
# end of the file (_after_ the last line)
These are documented in 3.30, but not explicitly in 5, although there
is a reference to +n under the Move command (line1,+n,line3 M).
This can be useful for scripts, eg to delete the last n lines of a
file:
#
-n,.d
e
To delete all except the last n lines
#
1,-Md ;where M is n+1, since # is _after_ the last line
e
To delete all except the first n lines
n
;CR (or ^C) to terminate editing of line
+1,#d
e
Mitch Ames
===============================================================================
15) FDISK
FDISK /STATUS ?
Prints a screen just like using option 4 of fdisk "Partition
information", but includes extended partition information.
Nice if you want to get an overview without fear of pressing
the wrong keys.
Armin Hanisch
Doesn't work in Ver 3.30.
Mitch Ames
FDISK /MBR
MS-DOS 5.0 FDISK has an undocumented parameter, /MBR, that causes it
to write the master boot record to the hard disk without altering the
partition table information. While this feature is not documented, it
can be told to customers on a need-to-know basis.
What is the MBR?
At the end of the ROM BIOS bootstrap routine, the BIOS will read and
execute the first physical sector of the first floppy or hard drive on
the system. This first sector of the hard disk is called the master
boot record, or sometimes the partition table or master boot block. At
the beginning of this sector of the hard disk is a small program. At
the end of this sector is where the partition information, or
partition table, is stored. This program uses the partition
information to determine which partition is bootable (usually the
first primary DOS partition) and attempts to boot from it.
This program is what is written to the disk by FDISK /MBR and is
usually called the master boot record. During normal operation,
FDISK only writes this program to the disk if there is no master
boot record.
Why is the MBR changed during Setup?
During installation of Microsoft MS-DOS 5 Upgrade, Setup will replace
the master boot record on the hard disk with code to display the
message:
The MS-DOS 5.0 Setup was not completed.
Insert the UNINSTALL #1 diskette in drive A.
Press the ENTER key to continue.
This message should be erased and the master boot code rewritten
before Setup is completed. If a problem occurs during Setup and you
return to the previous MS-DOS, UNINSTAL should also remove this
message. However, should Setup or UNINSTAL fail to remove this
message, or should the master boot record become corrupted, a new
master boot record can be written to the disk using the following
command:
C:\>fdisk /mbr
Warning: Writing the master boot record to the hard disk in this
manner can make certain hard disks unusable. IE: those partitioned
with SpeedStor, or Microhouse's DrivePro program. It can also cause
problems for some dual-boot programs, or for disks with more than 4
partitions. Specific information is below.
WARNINGS:
This option should not be used if:
- the disk was partitioned using Storage Dimensions' SpeedStor
utility with its /Bootall option
- the disk was partitioned using MicroHouse's DrivePro program AND
the drive was NOT setup using a standard CMOS value.
- more than 4 partitions exist
- certain dual-boot programs are in use
Storage Dimensions' SpeedStor utility using the /Bootall option
redefines the drive's physical parameters (cylinder, head, sector).
/BOOTALL stores information on how the drive has been changed in an
area of the master boot record that MS-DOS does not use. FDISK /MBR
will erase that information, making the disk unusable.
MicroHouse's DrivePro program functions similarly to SpeedStor above,
and has the same boot record vulnerability. MicroHouse identifies their
boot program at boot-up by a small MICROHOUSE logo near the left side of
the screen about two-thirds down, at power on. If you see this logo,
do NOT use FDISK /MBR, or the drive will become unusable.
Some older OEM versions of MS-DOS and some third-party partitioning
utilities can create more than 4 partitions. Additional partition
information is commonly stored information on partitions in an area
that FDISK /MBR will overwrite.
Some dual-boot programs have a special MBR that asks the user which
operating system they want on bootup. FDISK /MBR erases this program.
Dual-boot systems that boot whichever partition is marked Active are
not affected by FDISK /MBR.
Edited: MicroSoft Publication
forwarded by Don Dean
editing suggestions made by
Matt Mc_Carthy (info re:
MicroHouse's DrivePro)
If you have a Boot Sector Virus, just boot from a known "clean"
floppy disk (which has the System files and FDISK on it - IE:
your "disaster recovery disk") and run FDISK /MBR. Bye, Bye Virus!
Gary Cooper
Make sure it's write protected.
Jasen Betts
[Begin quote]
One of the FDISK functions, updating the Master Boot Record (MBR),
does not appear on any of the FDISK menus. The Master Boot Record is
located at the beginning of your primary fixed disk. It is composed of
two parts -- the master boot code and the partition table. The master
boot code is a short program that determines which operating system
will start the computer, then transfers control to that operating system.
The partition table contains information about the partitions located on
the fixed disk.
The Master Boot Record may need to be updated when:
* An operating system other than MS-DOS is on the fixed disk.
Some operating systems replace the master boot code with their
own program, which may not allow MS-DOS to start the system,
even if the partitions are valid DOS partitions. If this condition
exists, updating the Master Boot Record will replace only the master
boot code.
* The information at the beginning of the fixed disk has been
overwritten. The partition information is destroyed and the fixed
disk will no longer start any operating system. If this condition
exists, updating the Master Boot Record will replace both the master
boot code and the partition table. However, the partition table will
not have any defined partitions.
If you cannot get your system to start MS-DOS from the fixed disk and
you are sure the initialization process was performed correctly, you
may need to update the Master Boot Record. To do this, enter the
following command:
FDISK /MBR
FDISK does not display any menus or messages while it is updating the
Master Boot Record. When the procedure is complete, the MS-DOS
prompt is displayed.
If you are unable to start MS-DOS from the fixed disk after updating
the Master Boot Record, you may need to partition and format your fixed
disk. If you still cannot use the fixed disk to start MS-DOS, contact
your Authorized COMPAQ Computer Dealer for further assistance.
[End quote]
Compaq DOS 4.01 Manual
Submitted by
Paul Maserang
If the situation at hand involved a trashed partition table. This
regenerates the partition table, but does NOT restore the user
partition information in it. Therefore, after using FDISK /MBR, you
must still use FDISK without the /MBR switch to re-enter the partition
information before you can do anything else. If the newly entered
partition information is identical to that which existed there prior
to the partition table being trashed, and nothing else has been damaged,
there should be no need to reformat the drive, because the boot sector,
FATs, directories, and data should still be undisturbed. If the boot
sector or either of the two hidden system files (IBMBIO.COM/IBMDOS.COM
or IO.SYS/MSDOS.SYS) are damaged, the SYS command can be used to restore
them without losing anything else.
Paul Maserang
I work _only_ with the Microsoft versions, and have not had the
same experience. The /MBR parameter _only_ rewrites the MBR. It
does not affect the partition information. I use it daily on
various machines and have not lost one byte of data.
Matt Mc_carthy
I guess you didn't know that "Master Boot Record" and "Partition
Table" refer to the same thing. What you're talking about is the
master boot CODE, the executable code that accompanies the
partition table and is located on the same physical sector (0).
Here's what I find in the first few bytes of my physical sector 0
(unassembled with DEBUG after copying the sector to a file):
2BB7:0100 33C0 XOR AX,AX
2BB7:0102 FA CLI
2BB7:0103 BED0 MOV SS,AX
2BB7:0105 BC007C MOV SP,7C00
2BB7:0108 BEC0 MOV ES,AX
2BB7:010A BED8 MOV DS,AX
2BB7:010C FB STI
2BB7:010D 8BF4 MOV SI,SP
2BB7:010F BF0006 MOV DI,0600
2BB7:0112 B90002 MOV CX,0200
2BB7:0115 FC CLD
2BB7:0116 F3 REPZ
2BB7:0117 A4 MOVSB
2BB7:0118 EA1D060000 JMP 0000:061D
I also find the following text in the first half of the sector:
Missing operating system. Error loading operating system. Invalid
partition table. Author - Siegmar Schmidt
I have only one partition on my C: drive, and its information is
in the last of four possible positions in the partition table.
The first significant byte (non-zero) is at offset 01EEh in
physical sector 0.
The rest, from offset 00EDh to 01EDh is nothing but 00h.
So it would appear that everything from offset 0000h to 00ECh is the
Master Boot CODE, and everything from 00EDh to the end of the sector
(01FFh) is the Master Boot RECORD (aka partition table). More likely,
the partition table probably begins at offset 0100h, and takes up the
last 256 of the 512 bytes available in the sector.
Beginning with the first significant byte of my partition table (at
offset 01EEh), this is what mine shows:
80 01 01 04 03 91 65 11 00 00 00 07 A3 00 00 55 AA
^^
This first byte, I think, is the drive on which this partition
is located, and the next byte might indicate that this is the
first (primary) partition (in my case, the ONLY partition for
this drive).
Now, according to my manual, FDISK /MBR can either re-write only
the Master Boot CODE when necessary; or it can re-write both the
Master Boot Code AND the Master Boot RECORD, if it determines that
the partition table has been corrupted.
If it does re-write both, then you do have to use FDISK without
the /MBR switch after using it with the switch, because the
re-written partition table has no defined partitions until you do.
But when you use the /MBR switch, it produces no screen output
(at least not on the version I'm using), so you don't know whether
it did both or just the code. So you should still check to see that
you have a valid partition by using FDISK without the /MBR switch
afterwards.
Paul Maserang
===============================================================================
16) FOR IN DO
FOR %%V IN (/SOMETHING)
LEADING SLASH WITH FOR IN DO LOOP
In the FOR statement in the INIT and COUNT routines below the
parameters in the () show a leading "/". This seems to separate
the first digit of the environmental variable used within the
brackets (). Am I correct? Is this documented anywhere?
:================= INIT =================
set &=%4&|set n$=%4|set m$=%3|set #=%2|set !=%0
if not '%m$%'=='0' for %%a in (/%m$%z) do if '%%a'=='0' set @=0
%!%
:================= COUNT ================
if '%&%'=='&' goto PROCESS
for %%a in (/%&%) do set &=%%a
Peter Joynson
I have read some articles about this in PC Computing & PC Magazine.
I don't believe it is documented anywhere but you're right, it strips
off the first character of whatever string is passed. I will try to
find one of the articles that explains it better if you need it.
Robert Hupf
Correct. I believe it is not documented (up to DOS 5 anyway) by MS,
but I have read from other sources that the leading / will split an
item into the first character and everything else. Eg:
for %%n in (/hello there) do echo %%n
will display "h", "ello" and "there". "There" is not split because
it is a separate item, delimited by the space. If used with an item
including wildcard (? or *) characters the item will not be expanded
to the files which match it, thus allowing inclusion of those
characters in the set. Eg:
for %%n in (/? /*.bat hello) do echo %%n
will display "?", "*", ".bat", "hello". This apparently is the
original reason for the feature, but it may also be used recursively
to parse a string one character at a time.
Mitch Ames
... quoting Dirk Treusch to All ...
How can a batch file (without 4DOS) determine from which drive it has
been started?
Example: C:\> a:test.bat
Now my batch should be able to find out that it is located on drive A:
(not the path - only drive!).
Mitch Ames responds:
The variable %0 contains the name of the batch file
_as_it_was_typed_at_the_command_line. If you call the batch file as
A:TEST.BAT, %0 will be "A:TEST.BAT". If you have the directory on
your path, and simply type TEST, then %0 will be "TEST". The drive,
path and extension will only appear in %0 if you enter them in the
command used to call the batch file (either typed at the command
line, or called from another batch file).
So you _must_ specify the drive as part of the batch filename for
this to work. To extract the drive only, use STRINGS, or similar (I
don't have a copy, so don't ask me to post it). Alternatively use
the undocumented FOR %%V in /SOMETHING command, eg:
set drive=
for %%v in (/%0) do call test2 %%v
echo Calling drive is %drive%
where TEST2.BAT is:
if not '%drive%'=='' set drive=%1:
Disclaimer - I haven't tested this. Debugging is up to you.
(You can, of course, fit this into a single recursive batch file -
but that's left as an exercise for the student.)
FOR %%V IN (/SOMETHING) DO WHATEVER will do WHATEVER twice - the
first time with %%V set to the first character in SOMETHING ("S"),
the second time with all the remaining characters in SOMETHING
("OMETHING"). If SOMETHING is only a single character, WHATEVER will
only be called once, with that character in %%V. If the single
character is a wildcard (? or *) that wild card will _not_ be
expanded to a set of filenames. (The main purpose of this feature is
apparently to allow inclusion of the literal characters "?" and "*"
without them being expanded.)
This works in DOS 3.30 and 5 - I don't know about other versions.
Mitch Ames
Example:
I can get the date from the PC or from a file date stamp, but it's in
the format MM-DD-YY. I need it have the same date echoed in the file
name CDYYMMDD.ext
Brent Myhand
The only way know to accomplish this in pure DOS is to use an
undocumented feature of the "for" command. If the "set" starts
with "/", for responds twice, once for the first character and
once with all the remaining characters. To see this, at the DOS
prompt try:
for %x in (/abcde) do echo %x
You'll get "a" and then "bcde". So the general idea is to strip
off characters one at a time and build the new string. The problem
is that the command after the "do" looks the same for the two passes.
The only feasible command seems to be to call another batch file,
which can get you pretty deep into nested calls if you're not careful.
To distinguish the first and second call, you can set an environment
variable before the first call to "STEP1," and have the place called
change it to "STEP2." To prevent the nesting per character, you can
have the "STEP2" call save the remainder string in an environment
variable and iterate at the main level. I think you'll also need a
flag to tell you if you're working on the Month, Day, or Year part
of problem.
And, do you really get a 2 digit year, or do you get a 4 digit year?
I think this does it:
%echo off
if NOT (%1)==(MORE) GOTO INIT
if (%STEP%)==(STEP1) GOTO STEP1
if (%STEP%)==(STEP2) GOTO STEP2
GOTO END
:INIT
set STEP=STEP1
set STR=%1
set STAGE=M
set DAY=
set MON=
set YEAR=
set YYMMDD=
:LOOP
for %%x in (/%STR%) do CALL %0 MORE %%x
if (%STR%)==() GOTO FINISH
GOTO LOOP
:STEP1
set STEP=STEP2
set STR=
if (%2)==(-) GOTO NEWSTAGE
if (%STAGE%)==(D) set DAY=%DAY%%2
if (%STAGE%)==(M) set MON=%MON%%2
if (%STAGE%)==(Y) set YEAR=%YEAR%%2
GOTO END
:STEP2
set STEP=STEP1
set STR=%2
GOTO END
:NEWSTAGE
if (%STAGE%)==(D) set STAGE=Y
if (%STAGE%)==(M) set STAGE=D
GOTO END
:FINISH
SET YYMMDD=%YEAR%%MON%%DAY%
set STEP=
set STAGE=
set DAY=
set MON=
set YEAR=
:END
If you need to trim 4 digit years down to 2 digits, you'll need to
add some STAGES.
William Lipp
The / causes the FOR command to break %1 into two parts:
the first character of %1 and the rest of %1. Take the line:
for %%v in (/%1) do set word=%%v
Say that %1 equals Lang, first time through word will be set to L,
second time though it will be set to ang. Without the / it would
be set to Lang.
This is a very useful trick to know.
Scott Lambert
From the command prompt type in
for %x in (/abcd) do echo %x
You will get "echo a" followed by "echo bcd". The leading "/"
causes "for" to split the string into the first character and
the tail.
if %1 is abcd, then line
for %%v in (/%1) do set word=%%v
results in
set word=a
set word=bcd
so word ends as "bcd".
then the line
for %%v in (/%1) do if %%v%word%==%1 set char=%%v
results in
if abcd==abcd set char=a
if bcdbcd==abcd set char=bcd
so char ends as "a"
The other lines handle the case where %1 is only one character.
William Lipp
... why won't this work:
for %%f in (/h /H -h -H /? -?) do if "%1"=="%%f" goto @Help
Rene Verhagen
What you could do to override this problem, is very simply write:
for %%f in (H h ?) do if "%1"=="/%%f" goto @help
for %%f in (H h ?) do if "%1"=="-%%f" goto @help
Raphael Neve & Gary Cooper
The H and h should work, but the "?" inside a for-in-do is expanded
by command.com into single-character filenames, so it would probably
give unexpected results.
Gerry Pareja
There are two problems here.
First problem is, when you use a ? or a * in the FOR set, it looks
for files that match the wildcard specification instead of using
the actual ? or * in the string.
Second problem is, the / calls up an undocumented feature of the
FOR command. Try this from the command line:
FOR %I IN (/12345) DO ECHO %I
It loops twice, the first time produces a "1" and the second time
produces "2345". If there's only one character after the / it loops
once with just that one character.
We can do what you want, but we have to split the loop into two
lines. One to check for the /switch and another to check for
-switch
for %%i in (h H /?) do if "%1"=="/%%i" goto help
for %%i in (h H /?) do if "%1"=="-%%i" goto help
Because of the way / works in FOR sets, the /? sends a plain
question mark instead of "/?" or a list of one-character filenames.
Steve Reid
ADDITIONAL FOR IN DO WEIRDNESS:
Why does the following not work as expected?
for %%z in (test1 test2 test3) do goto %%z
goto end
:test1
echo test1
:test2
echo test2
:test3
echo test3
:end
Greg Frizzle
GOTO commands in FOR IN DO statements do not work correctly/as
expected. This fragment will work in 4DOS, but not with
COMMAND.COM. You've seen what happens when running under
COMMAND.COM already. 4DOS will display test1 test2 test3.
I was trying to explain... that GOTO's don't work right, and
that IF's will break FOR IN DO's.
Bill George
I fell for this, too. The strange thing is (on my MS-DOS 5
system), the output from this batch file is
test3
I don't know why it doesn't go to label test1 and then fall
through to
:end
Jim Long
I have been unable to break a FOR IN DO with an IF, nor do I
find that GOTO's function incorrectly. I suspect that there
might be some confusion here with the function in BASIC known
as GOSUB.
Peter Lovell
Bill George's point is a valid inclusion, I believe, because
GOTO's in a FOR IN DO statement do not work the same way that
other FOR IN DO's do. The FOR IN DO is only processed until the
first GOTO is executed, and does not repeat for all members of
the 'IN (set)' in the same way that MS-DOS treats other FOR IN
DO loops (i.e. it doesn't.(loop))
As far as IF's breaking FOR IN DO's I've had no experience of any
inconsistency and sadly BG's comment gives no examples. I've
tried several methods but cannot find any unexpected failures.
Mark J. Allen
I finally figured out how to manage some crude edlin scripts, but
found a serious weirdness: when running it under 4dos, it tends to
endlessly loop. I can't figure out why...
for %%a in (*.xxe) do edlin %%a < do.scr
And what I've found is that the batch will loop on it's own, so
that do.scr puts the text in each *.XXE file two or three times.
Todd Jacobs
I've got the feeling I'm not going to be able to explain this
particularly clearly, but here goes...
The reason for the looping is that the "for..in..do" loop will
go and get the next filename as it executes, rather than building
a table with the filenames in it and going through the table.
So, if you have three .XXE files, the loop executes three times,
then checks to see if there's a fourth file - and it finds another
three, namely the "new" versions of the original three which have
been edited and are now sitting somewhere else on your disk. So
it processes what it thinks are files four, five and six, then
looks for a seventh - and finds the same three files edited yet
again to look like files seven, eight and nine.
I believe this only occurs when the order of the files in the
directory - bearing in mind that the true order may not be visible
to you if you have overridden it with DIRCMD - is affected by the
operation which is being carried out in the loop, so for example,
merely reading the files will not cause this "weirdness", but
EDLINing them will, since the original file is renamed .BAK and
a new image of it is created elsewhere on the disk.
Rudy Lacchin
I want to see if an environment variable is equal to 00, and if
it is, change it to --. Something along the lines of:
set z=00
for %%x in (%a% %b% %c%) do if "%%x"=="%z%" set %%x=--
Can this be done?
David Farrington
:--- Initializing some variables ---
set A=VA
set B=
set C=00
:--- Your code ---
set z=00
for %%x in (%a% %b% %c%) do if "%%x"=="%z%" set %%x=--
set
:END
This will show the following:
A=VA
C=00
Z=00
00=--
Not quite what you wanted, but the effect is interesting and
worthy of saving in one's little bag of .BAT tricks. That
is, one can set a variable whose name is in a FOR index,
derivable from another variable or argument (or, I assume,
the name can be given directly via another variable or an
argument).
I was going to say, "the answer to your problem is simple"
and proceed to change your code by merely taking out a '%'
or two. But it doesn't seem possible. The straightforward
way to do it is not to use FOR at all, but simply
IF "%A%"=="%Z%" SET A=--
IF "%B%"=="%Z%" SET B=--
IF "%C%"=="%Z%" SET C=--
Terribly mundane, however. The challenge you pose relates to
a question I asked more than a month ago, and which stumped
me for a similar reason: it seemed impossible to retrieve the
CONTENTS of an environment variable when its NAME is itself given
as any kind of variable (an environment variable, an argument,
or a FOR index - anything requiring a percent sign for its
expression).
However, you have inspired me to give the problem a little more
thought, and I have found a way out, although it requires a batch
file to write and run another batch file.
The key to this is that '%%' in an ECHO statement gives us a
single literal '%'. (If for some reason this does not work,
perhaps you can still SET PCT=%% and get '%' as %PCT%).
Now, if we have PTR=NAM and NAM=VAL, we can get VAL from PTR thus:
ECHO SET GOTIT=%%%PTR%%% >TMP1.BAT
CALL TMP1.BAT
DEL TMP1.BAT
ECHO The answer is %GOTIT%
A similar technique will do what you want using FOR. It is
convoluted and relatively impractical with only three elements;
but if you had many to check, or if any of the components of
FOR() were themselves a variable, it might become an empowering
tactic:
if "%1"=="DO1" GOTO DO1
set A=VA
set B=
set C=00
set z=00
for %%x in (a b c) do call %0 DO1 %%x %z%
del TMP1.BAT
goto end
:DO1
echo IF "%%%2%%"=="%3" SET %2=-- >TMP1.BAT
call TMP1.BAT
:END
I am intrigued by this as a programmer in the C language, where
(as you probably know), indirection by means of pointers is
ubiquitous. It is common to use a pointer to refer to an element
of an array. It is less common, but still often useful, for a
pointer to mark one of several scalar variables. At run time
this is done via addresses, of course, not names. However, in
batch language, environment variables do not have addresses in
any practical sense, and their names are all we have by which to
grab them. Although the .bat application which first caused me
to think about this issue is long forgotten, I remain hopeful
that if we keep it in mind as a live option, uses will occur to
us.
Paul Emmons
On Sunday February 06 1994, Rob Flor wrote to Quang Sun:
QS>> For %1 in (TEFILE tefile GWS gws) do Goto %1
RF> ^ ^
RF> ÄÄÄÄÄÙÄÄÄÄÄ should be %%f ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ
RF> where "f" is
RF> alphabetic, not numeric.
I've seen a few people state that the control variable in a
for..in..do loop must be a letter, but %%1 and even %%? work
just as well. No?
Rudy Lacchin
I tested this and it works without a hitch even when there is
a %1 variable on the command line?
Gary Cooper
Unfortunately, FOR-loops cannot be nested. If they could, we
could say:
for %%f in (h H /?) do for %%g (// -) do if "%1"==(%%g%%f) goto @Help
Rene Verhagen
It *is* possible to nest FOR loops, by using COMMAND /C...
for %%f in (A B C) do command /c for %%g in (1 2 3) do echo %%f%%g
Steve Reid
for %%b in (zip arj arc lzh nws gif exe msg txt) do...
...if exist *.%%b goto files >nul
Terry Jackson
Your above example is working fine here under MS-DOS v6.22.
Vernon Frazee
for %%b in (zip arj arc lzh nws gif exe msg txt) do...
...if exist *.%%b pcopy *.%%b \tlxdump /x/ba >nul
The if exist still doesn't seem to work in this one.
Terry Jackson
Give it a try by CALLing PCOPY; like so:
...if exist *.%%b CALL pcopy...
Vernon Frazee
===============================================================================
17) FORMAT
EDITOR'S NOTE:
This section contains a discussion about how one may format a
disk(ette)s by the quickest means available. It is most difficult
to separate the various suggestions as the discussion blends from
one proposed method into the next, please bear with the text.
FORMAT A: /AUTOTEST
The autotest parameter will allow format to proceed, checking
existing format (unless the /u parameter is also present) and
proceeding with the format.
All this will take place with no delay and no waiting for user
input. It will also end without pausing. It will not ask for
a volume label or whether to format another diskette.
WARNING! This procedure will also work on hard drives! Be very
cautious if you plan to use this feature.
Wayne Woodman
FORMAT/U is not available in DOS 3.30
Mitch Ames
It won't take any other switches like /U, /S or /Q which is
a bit of a shame really.
When I try it with Dos6 I get the following error message:
Parameters not compatible.
Format Terminated.
Peter Lovell
/U and /S both work together with /AUTOTEST with my copy of
MS-DOS 6.00. Did you possibly use an illegal combination of
switches?
John Evans
With Dos 5 it certainly takes /u and /s as I have used it, in
fact I think /u is required if the disk is not pre-formatted
as the drive hangs up otherwise.
I would agree about /q though, this does not work and gives
the error message you quote.
Terry Kreft
Have you ever tried:
FORMAT A: /Q /U /AUTOTEST
Pete Dinnella
This doesn't work in my DOSs (IBM DOS 5.02 and OS/2). You can't
combine /Q AND /AUTOTEST
Asbjorn Hojmark
I have loaded my F5 key with ANSI.SYS so when I press it I get
FORMAT A: /F:720 /U /AUTOTEST
This DOES work.
Pete Dinnella
EDITOR'S NOTE: In response to requests for the fastest way to
format diskettes. Vernon Frazee has offered the following
solutions. These techniques generated a great deal of
discussion pertaining to the validity and relative merits of
each method.
REN /?|FORMAT %1 /q /u /v:"%2">NUL
Most of the solutions I've created and used, or seen... echoed
the necessary responses out to a temporary file, redirect the
contents of that file back to the FORMAT command, and then deleted
the file. Inefficient!
If you type the command:
format a: /q /u /v:""
FORMAT will 'quick format' a diskette in A:, unconditionally, and
without prompting for a volume label, which is all well and good,
BUT for many, the two prompts:
Insert new diskette for drive A:
and press ENTER when ready...
and then:
QuickFormat another (Y/N)?
get real old after a while. We DON'T have time to play. We wanna
slam a disk in the drive, hit a few keys and have a formatted disk
ready to go... now! <g>
The solution of course is some way to send a "carriage-return"
response to the first prompt, and then a "N" and "carriage-return"
to the second. And, like I stated above, most use a temporary
file to store these keystrokes and then delete it.
Well check it out. If you're using MSDOS v5.00 or higher (haven't
tried it with anything earlier yet) stick a previously formatted
diskette in drive A: and try the following command:
ren /?|format a: /q /u /v:""
and the text generated by the "REN /?" portion of the command lands
you back at the DOS prompt no questions asked! Yea yea, I know, the
output is ugly but hey, it works! If you'll simply add a ">nul"
(not the quotes) to the end of the line it'll hide the mess.
Here's my QF.BAT(ch) solution built around the above:
@echo off
:QF.BAT - Quick Formats diskette in specified drive (with
: optional volume label). Type "QF /?" for syntax
for %%x in (a A b B) do if (%1)==(%%x:) goto BEGIN
for %%x in (a A b B) do if (%1)==(%%x) QF %1: %2
:Syntax .................................................
echo Syntax: QF d[:] [volume_label]
echo Where: d is either drive A or B, (":" optional)
echo and: volume_label is an optional volume label
goto END
:BEGIN ..................................................
echo Quick formatting diskette in %1...
if not (%2)==() echo and adding label "%2"
ren /?|format %1 /q /u /v:"%2">nul
echo Task complete.
:END .............................................. -vjf-
If you'll stick the above in a directory in your PATH all you have
to do to 'quick format a diskette in A:' is type:
QF A
(or "QF B") and you'll have "no questions ask" formatted diskette
ready to go in 7-8 seconds.
Vernon Frazee
EDITOR'S NOTE: This shorter version of QF.BAT eventually evolved
into the following:
"a BATch file named QF (Quick Format) that ONLY allows formatting
diskettes in drive A: or B:. The entire BATch file is built around
the single command (which I use in a DOSKEY macro instead of a
BATch file):
ren /?|format %1 /q /u /v:"%2">nul
Here's my QF.BAT solution (again):
@echo off
:QF.BAT v1.1 -----------------------------------------------------------
:Purpose: Quick Formats diskette in specified drive (with
: optional volume label). Type "QF /?" for syntax
for %%x in (a A b B) do if (%1)==(%%x:) goto BEGIN
for %%x in (a A b B) do if (%1)==(%%x) QF %1: %2
:Syntax ----------------------------------------------------------------
echo Syntax: QF d[:] [volume_label]
echo Where: d is either drive A or B, (":" optional)
echo and: volume_label is an optional volume label
echo Note: DOS's CHOICE.COM is used if an error occurs
goto END
:BEGIN -----------------------------------------------------------------
echo Quick formatting diskette in %1...
if not(%2)==() echo and adding label "%2"
ren /?|format %1 /q /u /v:"%2">nul
if errorlevel 4 goto ERROR
if errorlevel 3 echo Task terminated.
if errorlevel 3 goto END
if errorlevel 0 echo Task complete.
if errorlevel 0 goto END
:ERROR -----------------------------------------------------------------
echo.
echo Error reading drive %1!
echo.
echo a) Is the disk inserted correctly and the drive door closed?
echo b) Maybe the disk is write-protected or "%1" is the wrong drive?
echo c) Has the disk in drive "%1" ever been formatted before?
echo (QF won't work on a disk that's never been formatted).
echo.
choice /c:ar Your choice: Abort or Retry
echo.
if errorlevel 2 goto BEGIN
echo Task aborted.
:END ------------------------------------------------------------- -vjf-"
Vernon Frazee
EDITOR'S NOTE: In response to these suggestions Vernon received
the following feedback:
If you type the command:
format a: /q /u /v:""
FORMAT will 'quick format' a diskette in A:, unconditionally, and
without prompting for a volume label, which is all well and good,
BUT for many, the two prompts:
Vernon Frazee
Have you ever tried:
FORMAT A: /Q /U /AUTOTEST
The undocumented /AUTOTEST switch will not ask you to insert a
disk nor will it ask for a volume label or if you want to format
another! I have loaded my F5 key with ANSI.SYS so when I press
it I get
FORMAT A: /F:720 /U /AUTOTEST
(I use a lot of 720k 3.5's) Now with the press of a single key I
pump out a 720 floppy pretty damn quick! Try it! P.S. I know this
works with DOS 6.0. Don't know about 5.0 and below!
Pete Dinnella
I did... on every version of MS-DOS since 4.0. And neither of the
undocumented FORMAT parameters, "/AUTOTEST" or "/BACKUP" will work
with the "/Q" parameter. In fact both return the same error message:
format a: /q /u /v:"" /autotest
and,
format a: /q /u /v:"" /backup
return the error:
Parameters not compatible.
Format terminated.
Vernon Frazee
Question, Why not redirect a text file with the necessary
keystrokes in it to the format command?
William Johnson
1) If you store the "text" file on the hard drive permanently it's:
a) Wasting a minimum of one cluster and
b) You have to wait for DOS to find and read the file
(so it can redirect it to the FORMAT command)
2) If you are echoing the keystrokes out to the "text" file instead,
you have to wait for:
a) DOS to write the file
b) DOS to find and read the file (to redirect it to FORMAT)
c) DOS to delete the file
Vernon Frazee
You did great down to here, Vernon! The rest is wrong.
VF> ren /?|format a: /q /u /v:""
is faster because it uses REN (a DOS command already in memory).
(It doesn't have the additional delay of reading and/or writing
the extra "text" file to and/or from a slow mechanical disk).
To test what I'm saying, Vernon, use a .BAT such as this:
@echo off
set xemp=%temp%
set temp=a:\
ren/?|format b:/q/u/v:""
set temp=%xemp%
set xemp=
If you want to read the output of REN/? from drive A:, just
UNDELETE the newest file on drive A: and read it. If I remember
right, the pipe puts TWO temporary files on disk that have to be
deleted. One of those is zero length and can't be read but it's
still an additional file that must be written and subsequently
deleted from the disk.
It seems that this should be covered in the DOS manual but if it's
there, I've never seen it.
Billy Gilbreath
EDITOR'S NOTE: In response to another suggestion from Vernon Frazee.
FORMAT A: /Q /U /S /V:"" /F:1.2
Vernon Frazee
/Q and /U are mutually exclusive options. Actually, it just kind
of ignores the /q. Also putting the "/U" is really unnecessary
unless you have reason to suspect bad media. If "/Q" cannot
determine the media type, it defaults to "/U" format.
Steve Adams
/Q is not kind of ignored at all.
/U is by no means unnecessary, if you do not use it then format
will check the disk and save the "Unformat" information, this
takes time, try doing a quick format with /U and without it, the
difference in processing time is significant.
Also /Q does not "default" to /U format, it asks for user input
as to whether it should proceed with an unconditional format,
sometimes!
Following this message I spent two hours playing around with
FORMAT, and the number of responses it gave to differing
conditions was quite remarkable.
For instance when I said that /Q does not default to /U but
requires user input sometimes I was referring to the following
cases:
MSDos 6.20, 1.44m floppy drive:
1.44m floppy disk, unformatted.
Command line> FORMAT A: /V:"" /Q /F:1.44
The user is _not_ asked whether to carry out an unconditional
format, FORMAT just carries on and does it.
720k floppy disk, unformatted.
Command line> FORMAT A: /V:"" /Q /F:720
The user is _not_ asked whether to carry out an unconditional
format, FORMAT just carries on and does it.
So what does the following command line do (1.44m floppy disk):
Command line> FORMAT A: /V:"" /Q
You would think that this should work the same as example (1)
above as the /F:1.44 should be implied. It doesn't, the user
is _asked_ whether to perform an unconditional format, it does
not just carry on and perform one.
I found a number of anomalies in the way format handled different
disk sizes in the above set-up and the conclusion I reached was
that it was unsafe to reach a conclusion on _anything_ format
will do, without trying the specific situation out first.
The one thing I did find though was that /U gives significant
speed improvements in all situations (maybe! <G>).
Why do you use the /f switch with format /q as it is redundant,
the /q forces the disk size to be retained anyway. Please see
below for a test of this I did.
DOS screen capture Comments
============================================ ========
C:\format a: /q /u /v:"" /f:1.44 +- Note /f:1.44
Insert new diskette for drive A: |
and press ENTER when ready... |
|
Checking existing disk format. |
QuickFormatting 720K +- Note its actually
Format complete. | formatting to 720k
| as this was the
| original disk
730,112 bytes total disk space | size.
730,112 bytes available on disk |
|
1,024 bytes in each allocation unit. |
713 allocation units available on disk. |
|
Volume Serial Number is 3F2D-13DE |
|
QuickFormat another (Y/N)?n |
|
C:\ +- Done
So as I say the /f is redundant.
Terry Kreft
FORMAT C: /BACKUP
This week I've read some articles in Dutch computer magazines about MUF's
which are very interesting (if you don't already know about them).
I already knew the FORMAT option /AUTOTEST, but new to me was the
/BACKUP option.
EXAMPLE: FORMAT A: /BACKUP
It seems to work exactly like /AUTOTEST, but it DOES ask for a volume
label.
Willem Van.den.broek
FORMAT/SELECT/U
is like DOS-Mirror... for safety-fanatics only
FORMAT/SELECT/U
makes disks unreadable (remember the U)
Reinhard Kujawa
Info from The German magazine PC PRAXIS
FORMAT /SELECT calls MIRROR after formatting.
Patrick Feisthammel
Here's a rough translation of what my DOS6 book (written by
Hans C. Nieder) says about it:
/SELECT/U This is a very dangerous option. Within 1 to 2 seconds,
and without further prompting, the disk(ette) will be
unformatted in such a manner as to make recovery
impossible. This might prove useful for reasons of
data protection, e.g. destroying sensitive data.
John Evans
FORMAT /H
In DOS 3.30 (I don't know about other versions), FORMAT /H
will cause the format to begin immediately after pressing Y
in response to "Format another?", rather than displaying
"Place disk to be formatted in drive A: and press Enter" on
a second and subsequent disks.
Mitch Ames
On 5.0 it comes back as "invalid switch".
John Mudge
===============================================================================
18) IF EXIST
IE: IF EXIST EMMXXXX0 GOTO APPLICATION
This is a handy quirk of DOS - installable drivers are seen as files
in all directories. You can use the if exist test to either test for
the existence of a directory, with "if exist <dirname>\nul", (which
fails if the directory does not exist because the nul device is not
found,) or to test whether a driver is loaded.
Caveats: you need to know the name of the directory or the driver
whose existence you are testing, and this is MS/DOS specific - it
doesn't work on network drives, and may not work under DR-DOS.
Gary Marden
This works definitely under DRDOS:
DR DOS Version 6.0
Copyright (c) 1976,1982,1988,1990,1991 Digital Research Inc.
Alle Rechte vorbehalten.
C:\>if exist emmxxxx0 echo ja
ja
Wolfram Serber
Where did you learn the "EMMXXXX0" name from?
Instead of typing MEM /C, type MEM /D for the "debug" listing.
That should give the names you're looking for.
Erik Ratcliffe
The trouble is, EXISTS returns TRUE for COM3/4 and LPT2/3 even
though the hardware does not exist.
Rudy Lacchin
if exist ?:\nul
does not return true on cd rom drives.
This can be a very effective copyright protection scheme for
programs distributed on cd rom disc. If the program is copied to
another media it won't run because "if exist <current drive>:\nul"
will be true. (Provided the author included such a check in their
code.)
Terry Blount
Verified this works with 4DOS too. Legal devices were XMSXXXX0,
DBLSSYS$, CLOCK$, NUL, AUX, PRN, CON, COM1 thru 4, and LPT1 thru4.
All returned yes to the statement: if exist device echo yes
Bill George
"If Exist" will only check for the existence of a file, but there
is a "Loophole" or "Quirk" in DOS that you can take advantage of.
Although they never show up in a DIR listing, any DOS DEVICE will
show up a file to
If Exist d:\path\devicename command
and it will return true if the directory "d:\path" exists.
Matthew Lewis
A little known quirk of the above, it will *always* say that the
directory \dev exists, even if it doesn't. Try it and see.
if exist \dev\nul echo yep
It's just Dos trying to be like UNIX. In UNIX, the devices exist
*only* in the /dev directory.
Steve Reid
===============================================================================
19) INSTALLHIGH
I think I may have found an undocumented feature for DOS 6....
I wasn't able to find this anywhere in the online help. It's
called INSTALLHIGH= and amazingly enough it works just like
INSTALL= but loads the file high!
The only drawback to this is: Memmaker will not go through and
add switches for that particular line during the "optimizing
process". It just takes it as it is currently. But then again
INSTALL= is ignored too!
Example:
DEVICE=C:\DOS\HIMEM.SYS
DEVICE=C:\DOS\EMM386.EXE NOEMS HIGHSCAN WIN=F500-F7FF WIN=F200-F4FF
dos=HIGH
dos=UMB
installhigh=c:\dos\share.exe
Robin Francis
MUF reported in the magazine C'T: You can use the DOS 6.0 command
"installhigh" in config.sys to load TSR programs into UMA. A 48 byte
environment will be added for every program. If you use it you don't
need the "loadhigh" in autoexec.bat any more.
But Memmaker can't handle installhigh!
Thomas Erbe
Further to Robins explanation, INSTALLHIGH cannot be directed to a
specific UMB area and thus defaults to largest currently available.
Like INSTALL it is processed (about) last of C.SYS lines and causes
more consumed RAM overhead than calling TSR from A.BAT or later.
Richard Pade
There is an undocumented CONFIG.SYS command called INSTALLHIGH. It
is similar to INSTALL except that it will load the TSR into an UMB.
It is available under DOS 6. However, it does not support the
/L and /S switches that DEVICEHIGH and LOADHIGH support.
Tom Dyas
Then it is useless, isn't it? It has less than the capabilities of
LOADHIGH and DEVICEHIGH but load the same TSRs that they load... no
wonder it is an undocumented command.
Wayne Moses
Just wondering, does INSTALLHIGH work with Microsoft DOS 5? It
would also be nice to know why it is undocumented. It doesn't do
anything major! Microsoft gains nothing by keeping it undocumented.
Loading TSR's from CONFIG.SYS is better because an environment is
not allocated for the TSR. A very small amount of memory is
conserved, but it is still conserved.
Tom Dyas
===============================================================================
20) MEM
MEM /A or MEM /ALL
Playing around with DOS 6.2 MEM command, I recovered a undocumented
Option (at least undocumented in the german version).
MEM called with option /? explains 5 options:
/D(EBUG), /F(REE), /M(ODULE), /C(LASSIFY) /P(AGE)
Not mentioned is the option /A(LL). I compared the output of a plain
MEM-cmd and the output of MEM/A; the only difference is following
additional line:
Freier Speicher im oberen Speicherbereich 1K (864 Byte)
(Free memory in high memory area (HMA))
/A is the only option forcing this statement.
Michael Dehlwes
It is not documented in my English copy of DOS 6.2 either, but does
work exactly as you (MD) described.
John Mudge
If you do a MEM /A it'll give you details of what's in the first meg
of memory.
Windoze owners get MSD.EXE (a pretty undocumented utility), that tells
you this sort of thing. If you do a MEM /A it'll give you details of
what's in the first meg of memory.
Ben Davis
What is this MEM /A in the MUF list supposed to do? Ben Davis says
that it's supposed to "give details of what is in your first meg of
memory." Don't the /P, /C and /D switches already do that?
When I ran it here under DOS 5.0, I got an "invalid switch."
Bruce Bowman
I am wondering if the switch "ALL" is documented in any DOS
manuals? It's not in the HELP command or the MEM /? command,
but it is a functioning switch and it is in the code, /ALL
reveals free HMA.
This is the MEM from the 6.22 Step-Up dated 5-31-94. Is this
available in prior versions?
Chad Wagner
It is avail in my 6.20... I too, was unable to document the
/ALL switch, either in the O/L help or in the 6.0 'manual'.
Bat Lang
MS-DOS Version 5.00
Invalid switch - /all
That's what I get when I try to run that command line here.
Darren Ryall
It's not in the PC-DOS 6.3 manual, certainly, but it's available
as a parameter both there and in MS-DOS 6.20.
John Gray
===============================================================================
21) MOUSE
MOUSE /U
Microsoft mouse driver version 8.1 has a /U switch. Adding that switch
loads all but 3.3k of the driver into HMA. It's not quite the most
recent version mouse driver, but hey, a mouse driver is a mouse driver
is a mouse driver, right? Especially when it only takes 3.3k of ram!
Mark Carter
Are you getting that result by loading the mouse driver high on a 286?
If so, that is good news. Mine takes up 12k of main RAM (MS mouse
driver ver. 7.0).
Gerry Pareja
Mouse 8.0 _is_ able to load itself into HMA (I think) on a 286 by using
the undocumented /U switch. I read it in PC Magazine sometime back.
Also, PC Mag said that the BUFFERS have to be set to a low value, e.g. 5.
Ng Cheng Kiang
===============================================================================
22) MULTIPLE DOS COMMANDS ON ONE LINE
set &=%4&|set n$=%4|set m$=%3|set #=%2|set !=%0
/|\ /|\ /|\ /|\
|_________|_________|________|____________Separators
The separators (|) used in the line, are these doing anything
other than separating commands? Can this be used for entering multiple
commands on any line in a batch file regardless of type of command?
Peter Joynson
I believe you are right about this, but I think it pipes any output from
the previous command to the next one (your example doesn't have any
output. For example: ECHO Y|ERASE *.* This would pipe the Y to the
command ERASE *.* so you wouldn't have to enter the Y for the "Are you
sure" prompt.
Robert Hupf
The | is a pipe symbol, well documented in your DOS manual. (Read it
before you read the rest of this message if you don't know about
pipes already, otherwise the rest won't make sense.) Pipes can be
used to put multiple commands on a single line, provided that the
first command does not write anything to StdOout which might cause a
problem when read by the second command as StdIn. Also, it is assumed
that you don't want to see the output of any but the last command,
since each command's output will be piped to the next's input. Note
that in this case SET neither writes anything to StdOut nor reads
StdIn. Thirdly, you must have write access to the current drive, or
%temp% if defined, since a pipe always creates a temporary file. Eg
this would not work if run from a write protected floppy (unless
%temp% was defined), since DOS would fail to create the temporary
files.
Pipes create temporary files even if no actual data is sent to
StdOut because Command effectively treats this:
prog1 | prog2
as something like this:
prog1 > %temp%tempfile
prog2 < %temp%tempfile
del %temp%tempfile
Even if prog1 doesn't create any output, at least one zero length
file is created. To demonstrate, try this
set temp=
set | dir
I must say this beats the usual boring old "how do I echo a blank
line in a batch file" etc.
Mitch Ames
I've done my share of DOS batch file programming but I just stumbled
across this this evening. Oh, I've known about ^M for some time but
saw them only as a pain in DOS->Unix file conversions. I never thought
about "power using" them under DOS. I mean, gee, we have our ANSI.SYS
driver, don't we?
If I were to it under Unix I would:
if [ -f bonk ]
then
echo "yes, bonk exists!"
echo "take a look:"
ls -l bonk
fi
notice the number of commands we can execute in this "nifty"
conditional statement. What I found that you can do under DOS is:
if exist bonk echo yes, bonk exists^Mecho take a look:^Mdir bonk
BTW, those "^M" are control-em's (ASCII 13)
Pat Goss
This works as is under 4DOS, but COMMAND.COM prefers a space after
the ^M's. It *assumes* that there are ^J's there.
Maynard Hogg
I will tell him that even if the file doesn't exist it will still
do:
echo take a look:^Mdir bonk
Chad Wagner
What versions of DOS is this supposed to work under? I tried it
with 4DOS, and it executed the second ECHO and the DIR whether the
file exists or not. Same thing running under MDOS' COMMAND.COM (MDOS
is OS/2's DOS emulator).
Scott Wunsch
ECHO.| TIME > TIMER.TXT
Would the pipe also work with del, ie Y|del *.*
Jeff Earle
===============================================================================
23) PATH
With MS-Dos 6.0 you CAN exceed the normal path length limit by
putting a "Set Path=C:\;..." in your Config.Sys file instead of
your AutoExec.Bat file. The usual limits do not apply there.
I have put in a path well over 800 characters and it works fine.
The path doesn't display correctly via PATH or SET, but it's in
there and it all gets searched.
I don't recommend having a path that long, mine is normally
only 6-8 directories.
Andrew Barnhardt
To change drive you need not extract the drive from the path.
If you have the path %P% for example, just do:
%P%\
cd %P%
Works with MS-DOS, Novell DOS (Don't know about 4DOS, PC-DOS).
Horst Schaeffer
Indeed it does work with MS-DOS. The backslash at the end of
the path is vital. Fortunately, it makes no difference if there
are two or more.
Gary Smith
That trailing backslash certainly does the business - I've always
stripped the D: never thinking that the simple addition of a
backslash would save lines of code.
I've never seen this before but can confirm that it works flawlessly
with MS-DOS v5.01a.
Mark J. Allen
Funny thing is: the path does not have to be valid, even some
delimiters will do the job, for example:
D:\\
D:NUL\
D:;=,\
But it will fail with wildcards (!)
Horst Schaeffer
Why do you want to peel off the drive letter and colon? Aren't
they part of the current directory?
Phi Nguyen
As a simple example, if you're on drive H: in the \FOOBAR
directory and you need to get to C:\WINDOWS you can't just
type:
cd c:\windows
Vernon Frazee
Under 4DOS, the first command will not only change the drive, but
it will also switch to that directory! ie. Current is D:\FILES\NEW,
I type E:\POINT\IN\, and poof! Current directory is E:\POINT\IN.
One of 4DOS' nicer features. This also worked under PC-DOS version
3.1, but you need to issue both commands (%P%\ and cd %P%).
Mike Ledoux
That's good news. Im use this trick in my INSTALL.BAT, and I wondered
if there were any problems with 4DOS or PC-DOS.
This is to make sure that the diskette drive is selected in an
INSTALL.BAT:
if not exist MYFILE %0\
where MYFILE is a specific file supplied on diskette.
Horst Schaeffer
EDITOR'S NOTE: In response to a request for information as to
how to add a directory to the current path via a batch file, I
made the following suggestion:
Since the current PATH is contained in the environmental variable
PATH, you could try using:
SET PATH=%%PATH%%;C:\DIR
This sets the new PATH (PATH) to contain the current EV PATH
(%%PATH%%) plus what you wish to add to the PATH (;C:\DIR).
However, the individual making the request expressed concern
about whether the current path ended with a ";" and how to
detect this possibility to avoid problems. One individual did
some experimentation and provided the following insight:
(Whether this qualifies as a true MUF I will leave open to
discussion)
Gary Cooper
This may not be neat but I experimented and found out that if
there are two semi-colons in a row in your path statement that
DOS just ignores this and sets your path anyways. For example
it doesn't seem to matter if your path statement/environment
variable ends in a semi-colon or not. So you can go ahead and
append ;C:\DIR to the end of your path and the path you wish to
add will be incorporated. It isn't the perfect solution if you're
"picky" but it works (at least in DOS 6.2). If you really have
to know if your path ends in ; then experiment with the FIND
command.
...with my autoexec.bat I found that if there are two semi-colons
in a row... your path is still set as you wish. This means that
you don't have to worry whether or not your path ends in a ; but
can go ahead and append ;c:\dir to your path. Works with DOS 6.2
anyway. If you are a perfectionist and don't want to see ;; in your
new path try using FIND /I to see if it will locate a ; at the end
of your path environment variable and then branch in your
install.bat file based on the errorlevel returned by FIND.
Russ Amiro
EDITOR'S NOTE: A common problem using MS-DOS is case sensitivity.
Gerry Pareja has demonstrated how PATH can be used to convert to
upper case. IE:
Begin with the valid commands and the "empty command" then put
a "goto :ERROR" on the next line:
if %1. == . goto :ERROR
if %1 == A goto :A
if %1 == B goto :B
if %1 == C goto :C
goto :ERROR
Thus the batch file will go to ":ERROR" if none of the
conditions are met.
Bruce Wilson
You'd still have to worry about upper-casing the input, or check
for both A and a, B and b, etc.
Here's a built-in upper-case routine (a DOS kludge!):
set dummy=%1
:: convert to uppercase:
set oldpath=%path%
path=%dummy%
set dummy=%path%
path=%oldpath%
set oldpath=
Now "dummy" contains an upper-case version of %1, so tests for %1
become tests for %dummy%. Works well.
(The explanation: "path=" forces uppercase, while "set path="
retains the original case. Don't ask me why. Ask Microsoft.... ;-)
Gerry Pareja
===============================================================================
24) REN or RENAME
Here's something that I believe qualifies as a MUF. It works in
MS-DOS 5.0 and probably in other versions as well, although I
haven't had an opportunity to test any.
You can create filenames with embedded spaces from the DOS
command line by using the RENAME command with the "?" wildcard.
For example, if you have a file named FILE.TST, the command
REN FILE.TST FILE?1.TST
will produce a file with the name "FILE 1.TST".
So far as I know, this feature has no practical use whatever.
Gary Smith
I tried this under MS-DOS 6.2. When trying to rename WIN4.TXT
to WIN?4.TXT, I got WIN44.TXT. To go back, I tried:
ren WIN??.TXT WIN4.TXT
it worked. Also, with a typo, I found that ren WIN4.TXT to
WIN4?.TXT gets a 'duplicate file name' message. Strange.
Julian Corey
The trick is that the question mark in the target filename must
align with an unused position in the source filename. Renaming
WIN4.TXT to WIN4?4.TXT works in this manner.
Gary Smith
Also works with 3.3, 4.01, 6.00 and 6.20.
John Evans
Because c.com normally uses the ? as a single char wildcard
this will work only if its char position in the destination
occurs past the end of the source file's name (as Gary's
example) and if it (or they, more than one ? is ok) are/is
followed by at least one valid character before the period.
I don't know of any useful function apart from ensuring unique
naming, perhaps, for temp files.
Mark J. Allen
Knowledge of this MUF has two possible uses to which I have
put it. It makes the file undeleteable unless you know that
renaming it to a legitimate filename can be done in the same
manner in which you created it. The renaming and running
then renaming back to a filename that makes the file
undeleteable and unrunnable can be done from within another
program in order to protect it.
Just knowing that your process can be reversed....
REN FILE?.TST FILE.TST
gives you the ability to save files that otherwise sometimes
appear and cannot be deleted or run...
John Mudge
EDITOR'S NOTE: The following excerpts were captured from a
discussion about the use of wildcard characters during the
process of renaming files. More experimentation may be
helpful in this area:
'?' is for single-character masking, '*' will match any
number including zero.
Don Hoffman
If DOS finds an asterisk, the rest of those 8 or 3 bytes is
filled up question marks.
Horst Schaeffer
I know that's what the books say, but it's not quite that simple.
If it were, it would only handle full 8/3 filenames.
'*' is very context-dependant. For RENames and COPYs it
almost never gives the desired result if it is accompanied by
other characters on the "target" side of the command.
Don Hoffman
I never had any problem with expressions like: XY*.Z*
(MS-DOS 5.0) Of course, any character succeeding an asterisk
is ignored.
Did you find any reproducible misbehaviour?
Horst Schaeffer
Let's see... I think REN ABC*.* ZZZ*.* was the sort of thing
that would really irk me. (It's been several years since I used
'*' in conjunction w/ characters on the target side of a command;
As I said, I learned better.)
I think I recall that the result would be 1 rename to ZZZABC?????.*
truncated to 8/, and a whole bunch of error messages about "File
Already Exists" for everything that truncated the same way. Of
course this also destroyed the ending characters (which I needed
for identification) of all the ones that did get renamed.
What I actually wanted could be obtained from REN ABC?????.*
ZZZ?????.*, explicitly requiring a full 8 on both source and
target, to get the desired ZZZ's while retaining the rest of
the original names for identification purposes. (2.x and 3.x
would give the "correct" result even from ren abc*.* zzz*.*,
but I broke myself of using it after spending half a day guessing
at filenames after 5.0 truncated fifty or so sequential backup
filenames on me in one fell swoop. Not cool. Not nice).
"Up"grading to MS 5.0 broke every batfile I had, one way or
another.
Don Hoffman
===============================================================================
25) REM
REM IN LINES WITH PIPES OR REDIRECTS
ie: REM echo y | del *.*
EDITOR'S NOTE: Michael Scheper reported that he encountered
problems when he tried to REM out an "echo y|del *.*" line in
his batch file.
...when that batch file was executed, I ended up with the
"All files will be deleted - are you sure?" message on my screen,
until I saw it the next morning. It was actually piping "echo y"
to "del *.*", which DOS didn't understand. It actually ended up
hanging my entire system, probably because it was only expecting
one character and not a whole line.
Michael Scheper
EDITOR'S NOTE: Here is the content of some of the responses
Michael received to his comment:
Try:
::echo y|del *.*
or even one ":" should do the trick. This just tells DOS that
the line is a label, and should work without a hitch (unless you
include a GOTO ECHO). Two ":" signs is the equivalent of a REM,
but should eliminate the problem you mention above.
Gary Cooper
It (the problem) appears to only occur if there is a pipe or
redirection in the line (REM'd out), leading me to believe that
DOS first handles pipes and redirections, then goes back to
find out what to do with them.
John Mudge
It's actually doing what it thinks you've told it: piping the
output of REM to DEL. Since REM _has_ no output (remember
REM > NULLFILE?), DEL hangs, waiting for the answer to its
question.
Gary Smith
What is happening here is that DOS reads the entire line, and
always processes redirection and piping *first*, regardless of
where they happen to appear.
Dennis Mccunney
===============================================================================
26) SWITCHES
EDITOR'S NOTE: The following commandline options are documented in
MS-DOS version 6.0+, some may have existed but were undocumented in
earlier versions.
SWITCHES=/W
Enables you to have your WINA20 file anywhere on your boot
drive. Without this you have to have it in the root directory.
Erik Ratcliffe
You should also mention that this one should not be used with
Windows 3.1. I've noticed a lot of people who do, and it wastes
around 120K of UMBs.
George Hannah
This is documented in DOS 6.0
Richard Pade
SWITCHES=/F
Do you know that there is a rarely known switch called /F?
If you put this line:
SWITCHES=/F
as the first line in your CONFIG.SYS, MS-DOS would not delay 2
seconds, but immediately start processing your CONFIG.SYS. This
trick has no other effects (AFAIK), but those who DO know better,
correct me if I'm wrong!
Samuel Tan Yi Hsuen
But where would you put the switch, it's not like you load a device
driver that early in boot up do you?
RF? Beats me. I think it goes in the SHELL= statement. Just don't
RF? remember what character you use. I saw it mentioned in the
RF? Tech conference /K maybe?
No, it's SWITCHES=/F, right?
Paul Senechko
Actually, its both:
/W allows you to move the WINA20.386 file
/K makes your AT Keyboard act like a XT
/F Disables the wait
/N Disables F5/F8 exiting
and to use any just put the command SWITCHES= and the parameters
on the first line of your config.sys (Can go on other lines, but for
the /F and /N you need it at the first line....), also the Switches
command IS compatible w/ DOS 5, but only using the /W & /K options
John Guillory
===============================================================================
27) TRUENAME
Internal DOS 5.0 command. Canonicalize a filename or path (using
DOS interrupt 21h, function 60) prints the actual directory.
SYNTAX
TRUENAME filename prints the complete path to file
TRUENAME directory prints the complete path to directory
Note: If the path is in a network, it starts with a \\machine-name
Michael Larsson
TRUENAME is analogous to the "whence" command in the UNIX Korn
shell. It returns the real fully qualified pathname for a command.
TRUENAME is useful in networks, where a physical drive may be mapped
to a logical volume, and the user needs to know the physical location
of the file. It ignores the DOS SUBST, and JOIN commands, or network
MAPped drives.
It is an undocumented MS/DOS feature, but is documented in 4DOS as
follows:
SYNTAX (Internal DOS 5.0 / 4DOS)
TRUENAME [d:][path]filename
PURPOSE
Returns a fully qualified filename.
COMMENTS
TRUENAME will see "through" JOIN and SUBST commands, and requires
MS-DOS 3.0 or above.
EXAMPLE
The following command uses TRUENAME to get the true pathname for a
file:
c:\> subst d: c:\util\test
c:\> truename d:\test.exe
c:\util\test\test.exe
Dennis McCunney
TRUENAME : will reveal the full name drive and path of the filename.
If you specify a wildcard ('*') in the filename, it will expand
the filename to use question marks instead. If the path includes
the ..\ sequence, TRUENAME will examine the directory structure and
calculate the path. Stranger still, the line:
TRUENAME \CRONK\FLIBBET\..\ART
produces the response:
C:\CRONK\ART
even if the directories \CRONK\FLIBBET and the file ART don't exist!
Don't expect this command to work across networks.
PC Magazine #212 Pg. 48-49
Forwarded by:
Rodney Atkins
I recently read a public message that said that there was an
unpublished command in DOS called "TRUENAME". I went to the
DOS prompt, and typed "truename /?", but all it said was
"Reserved file Name"... I ran it once, and it gave me two
extra prompts... any ideas?
Dan Knutson
TRUENAME gives you the true path of file(s) forgetting any
possible network re-direction, APPEND or SUBST.
Try this: go into a directory where you have CHKDSK.EXE and
type:
TRUENAME CHKDSK.*
You'll get something like C:\DOS\CHKDSK.EXE as an answer.
Raymond Paquin
If you don't mind me asking, where did you find out about
this command?
Dan Knutson
Just by looking at COMMAND.COM with the Norton Commander file
viewer. Near the end of COMMAND.COM, you can find a list of
the internal DOS commands, and TRUENAME is right there at the
end of it. Once I found it, I knew right off what it was probably
for, so I tried it out after using the ASSIGN, SUBST, and JOIN
commands, and it did exactly what I expected it to.
ASSIGN redirects commands intended for one physical drive to
another.
SUBST redirects commands intended for one physical drive to a
sub-directory on another drive (usually a hard drive). The
sub-directory becomes a logical drive with the drive letter
belonging to the drive being redirected.
JOIN is the reverse of the SUBST command, and causes a physical
drive to be addressed as if it were a sub-directory on another
drive.
Examples:
ASSIGN A: B: All commands (with a few exceptions) sent to
drive A: are now routed to B: instead. Drive
B: is still accessible as B: while this ASSIGN
command is in effect. Use ASSIGN with no
arguments to unASSIGN while not logged to the
ASSIGNed drive.
SUBST A: C:\WORK All commands (with a few exceptions) sent to
drive A: are now routed to the C:\WORK sub-
directory instead. The C:\WORK directory is
still accessible as C:\WORK while this SUBST
command is in effect. Use SUBST A: /D to
unSUBST while not logged to the SUBSTituted
directory.
JOIN A: C:\WORK This command creates a logical sub-directory
named WORK in the root directory of drive C:,
Use JOIN A: /D but all commands sent to it (with a few
to unJOIN while exceptions) are routed to drive A: instead of
not logged to a sub-directory on the hard drive. In this
the JOINed example, any reference to the C:\WORK
directory. directory will actually access drive A:.
[Note: A JOINed sub-directory can only appear
at root directory level -- ie: a
JOIN A: C:\DIR1\DIR2 command won't work.
Also note that, in this example, the C:\WORK
directory must either be empty or non-existent
for the JOIN command to work. And finally,
while JOIN is in effect, drive A: in this
example is NOT accessible as A: until JOIN
is terminated.]
In the first two cases, "TRUENAME A:" will return "B:/" and "C:/WORK"
respectively. In the latter, "TRUENAME C:\WORK" will return "A:\".
Other DOS commands that should NOT be used on a drive that is the
subject of an ASSIGN command include: SUBST, JOIN, BACKUP, LABEL,
PRINT, RESTORE. Furthermore, DISKCOMP, DISKCOPY, and FORMAT ignore
the effects of the ASSIGN command and work on the drive specified
in the command used. [Note: FORMAT calls LABEL when it finishes
formatting, so you can't use FORMAT anyway.]
Other DOS commands that should NOT be used on a drive that is the
subject of a SUBST or JOIN command include: BACKUP, CHKDSK, DISKCOMP,
DISKCOPY, FDISK, FORMAT, LABEL, RECOVER, RESTORE, and SYS.
The same applies to any other utilities that work with physical
drives instead of logical DOS drives, such as several of the
Norton Utilities. Don't use something like DISK DOCTOR (NDD)
on an ASSIGNed, SUBSTituted, or JOINed drive/directory.
Paul Maserang
...Sounds as if it could be handy when you know a filename,
but forgot what directory it was in; could save searching a
whole drive for it...
Don Kimberlin
If you use subst to re-define a directory as a drive, truename
returns the real drive and path, not the drive letter provided
by subst. The original example given for truename filename
assumes that you are already in the directory where the file
is located. As a matter of fact, if you issue the command
truename foo.bar
and foo.bar does not exist in the current directory, truename
will return the true path followed by foo.bar...Try it and see
for yourself.
Bill Mitchell
Actually, with DOS 5 here, the /? works just fine, and describes
what it is.
C:\WINDOWS>truename /?
Returns a fully qualified filename.
TRUENAME [drive:][path]filename
TRUENAME will see through JOIN and SUBST commands. It requires
DOS 3.0 or later.
The above was with DOS 5 and NDos from Symantec.
Cy Welch
That's because of NDOS. With COMMAND.COM from DOS 5.0, the /?
switch gives "Reserved command name."
Gary Smith
===============================================================================
28) VER
VER/R
Yields extended information about the OS Version. IE:
MS-DOS Version 5.00
Revision A
DOS is in HMA
Billy Gilbreath
Doesn't work with DOS 3.30
Mitch Ames
===============================================================================
29) %0
Note that %0 is (almost) always defined as the name of the batch file
itself (including drive\directory as typed at the command line). The
only time %0 is not defined is in Autoexec.bat when run by
Command.com at boot time (or command/p).
Mitch Ames
The %0 parameter is the name of the program. But wait, there's
more. If you want to test for the name of the program you are in!
What do your want to test for?
One time you type "edit", another you type "EDIT", another "EDIT.BAT",
another "C:EDIT.BAT", and another "C:\BELFRY\EDIT.BAT". How many
combinations do you want to test for at the start of your batch file?
You can map the file name to upper case and take care of some of the
problem as follows:
SET SAVEPATH=%PATH%
PATH %0
SET PROGNAME=%PATH%
PATH %SAVEPATH%
SET SAVEPATH=
To do the test, something like this might work:
FOR %%E IN (EDIT EDIT.BAT C:EDIT C:EDIT.BAT C:\BELFRY\EDIT...
...C:\BELFRY\EDIT.BAT) DO IF '%%E'=='%PROGNAME%' GOTO HIT
ECHO BAD COMMAND OR FILE NAME
GOTO ENDIT
...
:HIT
REM START EXECUTION HERE....
There is one last gotcha to %0. When AUTOEXEC.BAT is run by the bootup
sequence, %0 has no value. This is important if you want to find out if
you are in AUTOEXEC.BAT, and if you are in AUTOEXEC.BAT for the first
time.
I have seen this work with IBM's PC-DOS 3.10, various flavors of
MS-DOS 3.10, 3.30, 3.31, 4.01, and 5.00. It also seems to work
with DR-DOS 6.0. As to 4DOS, I have no idea, but would welcome
feedback on the matter (although 4DOS and DR-DOS hardly qualify
for a MUF entry....)
Mike Avery
So far as I know, it's not been documented anywhere 'officially',
but I did read about it in an article sometime back, probably
either in PC Magazine or in PC Computing.
Gary Smith
I've never seen it documented - it just bit me one day REAL HARD!
Well, the way I figured it was that when the boot process hands control
to AUTOEXEC.BAT, the normal command line interface isn't used, so %0
never gets set.
Mike Avery
This feature can actually be useful, because you can put
statements like this in your autoexec:
if NOT (%0) == () goto skip
[statements that should not be re-executed go here]
:skip
[statements that can be re-executed go here]
path...
set...
etc.
Then you can recreate your bootup environment at any time by
simply typing AUTOEXEC.
Gary Smith
===============================================================================
Other interesting information for MUF Explorers!!!
===============================================================================
30) ANSI
Anybody who knows what
DEVICE=ANSI.SYS /SCREENSIZE
-----------
means?
Karsten Weldingh
Well, first off, I don't know what it means.
But it certainly does exist. The HELP file in DOS 6.2 lists only
the /X /K and /R parameters.
But dumping the contents of ANSI.SYS reveals that the strings
/SCREENSIZE, /S, and /L are also present.
What they do is another question. I could certainly imagine that
ANSI would have every right to know what the screen size was. In
fact it couldn't function without knowing. But I haven't a clue
what the switch does.
Normally I don't answer questions just to say "beats me", but I
didn't see any other responses yet, and thought I'd at least tell
you that you weren't dealing with some oddball variant ANSI.SYS.
Gary Novosielski
EDITOR'S NOTE: John Gray asked:
Does anyone know if DOS keeps a record of the drive (probably drive
number) from where it was booted?
John Gray
"Undocumented DOS" says it is at offset+43h in the List of Lists in
DOS 4.0 and subsequent (1=A:). To get the LoL you do
mov ah,52h
int 21h
The pointer to the List of Lists is returned in es:bx.
Bob Stephan
===============================================================================
31) DBLSPACE and RAMDRIVE
I have recently bumped up against a problem with the way I want to
use DBLSPACE and RAMDRIVE (obviously DOS 6). It started with an
article in PC Computing (Oct 93, p.301) that detailed how to
DBLSPACE a RAM drive. I tried it, and it worked fine, until I
rebooted. To DBLSPACE the RAM drive, you have to place the commands
that create and resize it in AUTOEXEC.BAT, meaning that you have to
explicitly state the drive letter of the RAM drive and the compressed
volume that DBLSPACE creates. When I booted, RAMDRIVE.SYS used the
next letter up from what it was before (it was K:, now it was L:).
I went through all the steps again, and when I finished, the RAM
drive was up to M:! After a half hour of checking all my setups,
I finally realized that DBLSPACE reserves all drive letters up to
the highest one you have used. Since in the first iteration, the
highest drive letter I DBLSPACEd was K:, DBLSPACE reserved K: when
it is loaded in CONFIG.SYS. Since my call to RAMDRIVE.SYS came
after this, it used the next available drive, L:. I found the menu
in DBLSPACE that sets the maximum drive letter, but this is not a
permanent setting. If I went through the steps above again, I
would be chasing increasing drive letters again.
I can fix this obviously by swapping the order of the two calls, but
I thought this may be of interest to anyone having similar problems.
Greg Frizzle
===============================================================================
32) ECHO
ECHO Y|FORMAT C:\*.*
EDITOR'S NOTE: In response to a suggestion to use "Echo Y|FORMAT
C:\*.*" the following Undocumented switch was suggested:
FORMAT /X
You forgot to add the /X for formatting a fixed drive.
Clint Satterwhite
What is /X for? I know about /H and /AUTOTEST, is this another
version of it?
George Steinmetz
===============================================================================
33) EDIT
Here is some additional information about MS-DOS's EDIT program
which may not technically qualify as a MUF, but they do qualify
as obscure features:
[MS-DOS Edit]
Save changes and exit Do NOT save changes and exit
-+--+--+--+--+--+--+- -+--+--+--+--+--+--+--+--+--
[Alt] [Alt]
[Up][Up] [Up][Up]
[Enter][Enter] [Tab][Enter]
Vernon Frazee
Quit EDIT w/o saving: [Alt][Up][Up][Enter][Tab][Enter]
Something special: EDIT provides the usage of BOOKMARKS.
Key-bindings (German Version): Ctrl-K 0-3 Set Bookmark x to 4
Ctrl-Q 0-3 Goto Bookmark x of 4
Very useful when editing large files.
Michael Dehlwes
It SEEMS that MS has put out a new EDIT. I've often had a
problem because I've wanted to edit large files, and EDIT
(EDIT.COM 413 3-10-93 6:00) couldn't handle them. I found
EDIT ver. 0.9.019 on a BBS, virus scanned it, and have started
to use it. It is: EDIT.EXE (note .EXE not .COM), very large
(69,662), but handles files of AT LEAST 2.5 MEG. It's been
great for me. Other info: 10-17-94 0:00 (Is the 0:00 indicative
of beta version?) "Help, About" says it's MS-DOS EDITOR 0.9.019
copyright MS Corp 1994. Anyone know more about it?
I tried the ctrl-p ctrl-g for beeping in this editor:
Edit.exe won't allow a ctrl-P! (It beeps!) The ctrl-p ctrl-g
only works with EDIT.COM.
Interestingly, once I've put the beep into a bat file EDIT.COM,
when I call up the bat file with the new EDIT.EXE, the "large
period" IS there, and can be deleted, moved, copied... just like
any other character.
Search-and-Replace only does a Replace All for lines AFTER the one
the cursor is on (in the new EDIT.EXE), unlike the Change All
operation in the original edit.com, which makes the change
EVERYWHERE in the document.
Avi Tuchman
===============================================================================
34) EMM386.EXE
Windows in enhanced mode an error is generated stating my
EMM386 is in an invalid path. It's looking for the EMM386
in the A: drive (boot ROM).
Andrew Baker
To get around this problem, place the correct version of
EMM386.EXE into a directory which is accessible by all users.
Then in your CONFIG.SYS for your remote boot image include a
statement similar to the following:
DEVICE=EMM386.EXE 512 RAM /y=R:\WINDIR\EMM386.EXE
The /y option is an undocumented switch!
James Willmott
===============================================================================
35) FIND
Can someone tell me how one might test for case sensitivity under
4DOS? If I do the following:
if abc==ABC echo yes
if "abc"=="ABC" echo yes
Troy Prather
I would probably try to make a batch file solution for this. FIND
is case sensitive and returns an errorlevel (undocumented feature).
Not purely a 4/Ndos solution but then, not a solution at all, but a
clue.
James Mcgill
...pipe the output from your FIND to another FIND.
Jack Stein
It works, but it's dangerous if the files are huge-enough
to possibly exhaust space in %temp%... DOS may just quietly
lose the entire interim i/o w/o giving any indication at all.
Don Hoffman
DOS failure. Discovered in MS 5.0 rev A (upgrade); no others
checked. "Undocumented Function" in the sense that DOS is doing
something (highly improper) which, to the best of my knowledge,
is documented nowhere. Species: BUG.
Short Form: "Piped files may prematurely disappear without warning."
Long Form: During 'piping' an "OUT-OF-DISKSPACE" condition may go
completely un-acknowledged by DOS, to either the user, or to the
active program. DOS just quietly "loses it."
Example:
~~~~~~~
PKUNZIP -C bigfile *.txt|FIND "keyword"|SORT|LIST/s
Now the above should extract/decompress and concatenate all *.TXT
files from BIGFILE.ZIP and route that output to the CONSOLE, which
(in this example) is re-directed to the DOS FIND program, etc, via
automatic "pipe" files.
However, this example MAY FAIL at the UNZIP step due to full-disk
yet generate *NO* diagnostics or error message WHATSOEVER. Nor will
DOS necessarily return an "out-of-diskspace" (or any other error
indication) to the program which caused it. (PKUNZIP in this example.)
The subsequent program steps will *appear* to execute normally,
but in actuality they are receiving *NO* *INPUT*!
Hence, in the absence of final-step output, it is *NOT* possible
to tell whether the source material contained no targeted 'hits',
or whether the _intermediate_ data simply grew so large that it
exhausted all diskspace, and was silently discarded / deleted by
DOS.
remarks: "erratic"
~~~~~~~
1) Sometimes it returns an 'out-of-diskspace' indication to
the program doing the output, sometimes it doesn't.
(Tested with INT 21h/function 40h: "Write to File/Device".)
2) Also seems to behave differently depending on whether or
not the TEMP environmental variable is properly defined, and
what media (RAM or regular disk) is involved.
(TEMP is a specifier/keyword to DOS, telling him where to put
his temporary work files. If undefined/invalid, he will use
the 'current' drive / directory.)
3) UNDELETE can't give any useful information (if more than two
pipes are used,) as each successive step overwrites the FAT
entry of the preceding step; (Size field in particular.)
4) Reiterating: comprehensive tests were *not* carried-out once
the erratic nature became apparent.
Don Hoffman
===============================================================================
36) GENERATING RANDOM FILENAMES
EDITOR'S NOTE: In response to a question from Kyle Brost requesting
a method of generating random filenames using DOS, Mitch Ames offered
the following pure DOS solution.
I was looking for a line in a batch program that would give a
random name or set of numbers to a variable which would then make
a directory.
IE. %1=random name
MD\%1
CD\%1
Kyle Brost
You can make vanilla DOS generate a filename with a random name and
no extension by piping. This filename can then be fed into an EV.
Eg (:: has the same effect as REM)
:: RANDOM.BAT
:: create temporary dir (which will be empty)
md tempdir
:: tell DOS to put temp files there (saving old %temp%)
set org_temp=%temp%
set temp=tempdir
:: now pipe a CR to copy. This will create a non-zero length
:: file with no extension (*.) which will be copied as *.rnd
echo. | copy %temp%\*. %temp%\*.rnd
:: DOS will delete its temp files (*.) but _not_ the copies.
:: Change to the temp dir so that FOR command will not include
:: the directory in its variable
cd %temp%
:: remove the extension
ren *.rnd *.
:: now set a variable to the filename
for %%r in (*.) do set random=%%r
:: back to the original directory, delete the temp dir and
:: restore %temp%
cd ..
del %temp%\*.rnd
rd %temp%
set temp=%org_temp%
:: And show the results
echo %random%
:: Create a directory, and change to it
md %random%
cd %random%
I've tested RANDOM.BAT with DOS 5 and it seems to work OK. However
here are a few problems you might encounter.
This won't work with 4DOS because it generates temp files with
different names (eg P1.$02), and the FOR IN (/SOMETHING) trick
doesn't work properly. But if you use 4DOS you don't need all this
stuff anyway - see the next message.
Filenames generated by piping have a different format in different
versions of DOS. 5 seems to use any letters, whereas 3.30 uses
only hex characters (0-9, A-F).
DOS 3.30 does not seem to use the %temp% variable and always puts
temp files in the root directory of the current drive. There may be
other (than temp) files with nul extensions in the root.
Mitch Ames
===============================================================================
37) HIMEM
I keep on trying to install my himem.sys in my config.sys file so
that I can run different utilities that require it but every time I
reboot after I put the line in, it locks up.
Dana Harding
...try entering HELP HIMEM.SYS and reading all the online help.
Pay particular attention to loading sequence, and the switch option:
/MEMCHECK
Bat Lang
In the HELP I also noticed /Module, and this could occasionally
be useful, and quite some time ago I found /Page, very shamefacedly,
since for weeks I had cursed M$ when all the output from /Classify
had scrolled off the top of the screen, and I had forgotten to use
the MORE filter...!
John Gray
===============================================================================
38) IF
DOES A DRIVE EXIST?
I've just been playing around, and managed to come up with a way
to do it (check to see if a drive exists) in a batch file.
Just try to change to that drive, and DOS will return a non-zero
errorlevel if the drive does not exist.
Z:
If Not ErrorLevel 1 GoTo End
Echo Sorry, Drive Z: does not exist.
:End
This will work with MS-DOS 6.20. Can't say for other versions of
DOS, as I've only tried it on 6.20.
Matthew Lewis
===============================================================================
39) IF ERRORLEVEL
In a discussion regarding the correct syntax for:
IF ERRORLEVEL n GOTO LABEL
Vs.
IF ERRORLEVEL == n GOTO LABEL
Gary Smith had this to say to Robert Clark:
Actually, although the second form works, it really isn't legal,
and it's definitely undesirable...
Gary Smith
Sure it's legal. It's simply a matter of preference and/or style,
which wasn't the question. The fact is, _either_ construct
performs the same under MS-DOS--so a person may use the one that
makes more sense to him at the time. FWIW, I prefer to leave the
equality sign out, but only because it means less typing for me.
<G>
Robert Clark
Depends on your definition, I guess. Of course it's legal in
the sense that there's no law against it, but it's not part of
the documented syntax and it works more by accident than by
design. The reason I dislike it is because "==" generally means
"is equal to" and that is NOT how IF ERRORLEVEL works. I see no
point in writing intentionally misleading statements, even in
batch files.
Gary Smith
It does NOT display each errorlevel equal to or below, and that's
because I use if errorlevel == x (note the two equal signs).
Try it! At least I don't get more than one answer for errorlevels
like eight, under DOS 6.20.
Jonas Anden
===============================================================================
40) INTERLNK
I have a tip for Dos 6 users. I have a "no name" brand fax modem
card which has been working fine. I have logged onto many BBS's &
downloaded many megs of files & messages over past couple of weeks.
Today however I decided to upload a file (what a novel concept!!)
I run Telix, but the same happened under Terminate.
After selecting Z modem as the protocol, the file directory appears,
at which point the modem card hangs up the line Every Time. The
culprit was the Dos command INTERLNK which I had installed 2 weeks
ago. I had it set up on the parallel port so why it was effecting
the comms port is a mystery. Even using the following parameters
had no effect.
DEVICE=C:\DOS\interlnk.exe /LPT:2 /Noscan /V
Hope this saves someone the many hours it cost me.
Tony Nolan
Information forwarded by Gerry Pareja
===============================================================================
41) LABEL
:LABEL
DOS uses a leading : to indicate a label. If the next character
following the : is a space or other non-alphanumeric char, DOS
will decide it's an invalid label and skip to the next line,
performing no further action.
Dennis Mccunney
A colon followed by a space is exactly the same to DOS as ::, and
will *never* be seen as a label.
Bat Lang
EDITOR'S NOTE: Spaces between the colon and the first character of
the label are permitted in newer versions of MS-DOS but were
interpreted as invalid labels in earlier versions.
Give the following simple example a try:
@echo off
goto LABEL
goto END
: LABEL
echo This is ": LABEL"
:END
Vernon Frazee
Here's what Microsoft has to say on the subject:
GOTO--Note
Valid values for label
The label parameter cannot include separators such as spaces,
semicolons or equal signs
GOTO uses the first eight characters of each label
The GOTO command uses only the first eight characters of a label.
Therefore the labels "hithere01" and "hithere02" are both
equivalent to "hithere0"
Matching the label parameter with the label in the batch program
The label value you specify on the GOTO command line must match a
label in the batch program. The label within the batch program must
be preceded by a colon.
If your batch program does not contain the label that you specify,
the batch program stops and MS-DOS displays the following message:
Label not found
MS-DOS recognizes a batch-program line beginning with a colon (:) as
a label and does not process it as a command. If a line begins with
a colon, MS-DOS ignores any commands on that line.
Forwarded by Matthew Lewis
Both DM and I were guilty of applying yesterday's truths to today's
world. Apparently DOS 6 changed all of this, and neither one of us
caught it. We stand corrected.
In mitigation, however, I wonder how one is to learn of this, given the
documentation available; without finding out either in here, or thru
experimentation?
Although I have the last sizeable reference manual for DOS (5.0) it
has even less on the use of labels.
As a minimum, LABEL in MUF17 will require a qualifier, for applying
only to versions earlier than 6.0.
Bat Lang
What it should have said, and didn't, is that spaces between the
colon and the first character of the label are ignored.
Gary Smith
Can anyone find a version of MS/PC-DOS where a blank after a colon
and before a 'word' causes this NOT to be accepted as a label?
If not, I think my contention, that comments in BATch files are best
preceded by *two* colons, must stand.
John Gray
That DOS 2.1, as I recall, did not accept a blank after the colon.
Unfortunately I can no longer verify this vital fact. <g> If I get
a chance to try it on 3.3, I'll let you know what happens.
Gary Smith
I just booted a 2.x (OEM-tweaked MS 2.0) in the background and
checked: "Label not found" (and immediate termination of the batch
file) if a blank follows the colon. (Tried "::label" too while I
was at it... Identical response;)
Don Hoffman
Place 2 "::" in front of the line you wish to skip. DOS handles it
as a label, thus, doesn't try to execute it; it is faster.
::device=mouse.sys
Frank Starns
Only in AUTOEXEC.BAT, Frank; in CONFIG.SYS, DOS still gives the
"unrecognized command" error message.
Use ";" instead. DOS will ignore the line and not spit out an
error message.
Ron Warder
===============================================================================
42) MODE
COMMAS IN FILE SIZE:
mode co40
dir/-p %2|find "bytes free">>magic.bat
mode co80
Larry Nelson
Why change video modes?
I cut out the two `mode' lines and it still works great,
speeding operation a little and saving wear and tear on the
monitor.
Dennis Rush
That Mode thing is a trick that Vernon Frazee came up with
to beat the commas that DOS6+ puts in file size values. For
some odd reason Vernon took a look at a directory listing
while in mode co40 and realized that there were no commas
in the numbers. Who *ever* looked at anything in mode co40?
Vernon has a lot of idle time.
Mode co80
MAIL 33,474 07-11-95 7:02p
1 file(s) 33,474 bytes
155,590,656 bytes free
Mode co40
MAIL 33474 07-11-95 7:02p
1 file(s) 33474 bytes
155590656 bytes free
Command.com sees 33,474 as 33 474 the comma is seen as a space.
It looks nice but screwed up a lot of Batch files.
If the batch works OK for you then you must be running an older
version of DOS.
I ran into the same prob with Cache.bat below, but the Mode trick
doesn't seem to work for anything but Dir. I managed to whip it
with the lines....
echo if %%4 == cache set hit=%%3 >there.bat
echo if not %%4 == cache set hit=%%3%%4 >>there.bat
echo if %%2 == cache set mis=%%1 >and.bat
echo if not %%2 == cache set mis=%%1%%2 >>and.bat
Larry Nelson
Type the following command and note how it strips the ".ext"
MODE filename.ext
Vernon Frazee
For those who haven't tried this, the result is
Invalid parameter - filename
with the unusual property that it can be redirected (usually
error messages cannot be). You could then use the magic-named
batch file Invalid.bat to process parameter %3 as filename.
William Lipp
EDITOR'S NOTE: For those reader's unfamiliar with the "magic-named
batch file" which William suggests above with INVALID.BAT, here is
a sample MS-DOS magic batch which creates "Current.bat" on the fly,
and is used in this example with DATE and TIME. Conversion to
INVALID.BAT is left to Larry Nelson in his response to Chris Weisner
below. I credit Rudy Lacchin of the BatPower echo with the development
of the "magic named" technique, as in the following magic
Current.bat which I adapted from Rudy's method.
@ECHO OFF
CD\DOS
VER|DATE|FIND "Current" > TEMP.BAT
ECHO SET DATENOW=%%4 > CURRENT.BAT
CALL TEMP
ECHO ÉÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ» > DBOX.TXT
ECHO º º >> DBOX.TXT
ECHO º Date = %DATENOW% º >> DBOX.TXT
DEL TEMP.BAT
DEL CURRENT.BAT
SET DATENOW=
VER|TIME|FIND "Current" > TEMP.BAT
ECHO SET TIMENOW=%%3 > CURRENT.BAT
CALL TEMP
ECHO º Time = %TIMENOW% º >> DBOX.TXT
ECHO º º >> DBOX.TXT
ECHO ÈÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍͼ >> DBOX.TXT
DEL TEMP.BAT
DEL CURRENT.BAT
SET TIME=
CLS
TYPE DBOX.TXT
DEL DBOX.TXT
CD\
Gary Cooper
IE: Subject: FILENAME PARSING
I'm wondering if anyone has come up with a way to parse filenames
and extensions. I'm trying to convert subdirectories on the fly
from .xxx to .yyy, however using DOS FOR %%a in (*.xxx) do...
always provides the complete filename. I'm looking for a way to
strip the extension. Speed is not an issue.
Chris Wiesner
An obscure quark of the DOS Mode command, made known to us at BatPower
by one Vernon Frazee, solves the unwanted extension problem. When Mode
is called with a file name as a parameter (say TST.bat) it returns an
error message.
Invalid parameter - tst
It would appear that Mode chokes on anything not a standard Mode
parameter and if you will notice, the name of the file typed in
returns less .ext. This little bit of strangeness proves to be
fodder for a Magic.bat which can commit the newly stripped
filename to an envar where you can use it at will in your Batch
file. In X10.bat below I simply echoed the file name to the screen.
Kill the "set name=" line and the envar will stay in your DOS
environment until you reboot. That way other .bats can use it.
@echo off
cls
if %1! == ! goto hlp
mode %1>magic.bat
echo set name=%%3>invalid.bat
call magic
echo %name%
:cleanup
for %%q in (invalid magic) do del %%q.bat
set name=
goto L8r
:hlp
echo SYNTAX = x10 (filename.ext)
:L8r
Larry Nelson
===============================================================================
43) PAUSE
Have you tried using PAUSE `` instead of PAUSE > nul
Ron Dempsey
===============================================================================
44) SET
EDITOR'S NOTE: This section contains information about the
undocumented use of high ASCII characters in environmental
variables, but note also the use of LABELs and the fact that DOS
does not recognize the "=" characters in the labels used. Note
also that John discusses the possibility of two consecutive ";"
symbols occurring in the PATH statement. This possibility was
discussed earlier in the MUF list.
Those who were interested in the ADDPATH.BAT by Rob Flor and my
subsequent ADD2PATH.BAT and DROPPATH.BAT posted some time back might
like to compare them with this PCMag BATch file called PE.BAT, which
I found in a file of PCMAG files. Note that the original character
which I have replaced by '@' was the 1/4 symbol in code page 437,
hex AC, dec 172. You didn't know you could put
SET <one or more characters above hex 7F>=SOMETHING
and get a valid environment variable from this? Neither did I!
Note the recursive calls and about the only use of SHIFT I have
ever seen in a practical BATch file. There are a few things I
would want to improve, for adding: check the directory isn't
already in the path, not putting two semicolons when adding to
the end of the path if there was one already there at the end,
check there is enough environment space to hold everything...
and for deleting: check whether the path is already empty. In
fact, many of the comments in ADD2PATH and DROPPATH apply! That
said, it is an interesting and useful BATch file.
@ECHO OFF
:PE.BAT - Path Editor. Add or remove directories
IF '%2'=='' GOTO Help
IF '%1'=='+' GOTO AddEnd
IF '%1'=='&' GOTO AddBegin
IF '%1'=='-' GOTO Drop
IF '%1'=='@' GOTO DoDrop
GOTO Help
:===== AddEnd ========
PATH=%PATH%;%2
ECHO %2 added at end of path.
GOTO End
:===== AddBegin ======
PATH=%2;%PATH%
ECHO %2 added at beginning of path.
GOTO End
:===== Drop ==========
SET @=%PATH%
PATH=%2
SET PE_drop=%path%
:: Now variable drop contains %2 capitalized
PATH=%@%
SET @=
SET PE_rem=
:: Restart, passing PATH as parameters
%0 @ %PATH%
:===== DoDrop ========
SET PATH=
:== DropLoop
SHIFT
IF '%1'=='' GOTO DoneDrop
IF '%1'=='%PE_drop%' GOTO DidRemove
IF '%PATH%'=='' PATH=%1
IF '%PATH%'=='%1' GOTO DropLoop
PATH=%PATH%;%1
GOTO DropLoop
:== DidRemove
SET PE_rem=YES
GOTO DropLoop
:===== DoneDrop ======
IF '%PE_rem%'=='' ECHO %PE_drop% not found
IF '%PE_rem%'=='YES' ECHO %PE_drop% removed from path
SET PE_drop=
SET PE_rem=
GOTO End
:===== Help ==========
ECHO The options are:
ECHO %0 + directory : adds directory at end of path
ECHO %0 & directory : adds directory at start of path
ECHO %0 - directory : drops directory from path
ECHO Note that the PATH must not be empty.
:===== End ===========
PATH
### ends
John Gray
===============================================================================
45) SETUP
SETUP /G (possibly /E)
When installing MS-DOS 6.0, does not ask you for a blank, formatted
disk to restore the old DOS version from.
Alex Cohen
===============================================================================
46) SWITCHES
Anybody with any ideas what the /T-switch, like
SWITCHES=/T
does? It doesn't give any errors when used.
Karsten Weldingh
===============================================================================
47) %TEMP%
EDITOR'S NOTE: In a discussion about manipulating ASCII text
files the following was overheard:
But, doesn't DOS have to write the file somewhere anyway, as
it isn't clever enough to run a pipe otherwise... you have to
have say 100k of disk free if your file expands to 100k even
if you don't actually "see" the temporary intermediate file?
Robert Bull
You are 100% correct about this restriction/problem! In
fact I've (painfully) discovered that DOS will often give
NO INDICATION that diskspace is exhausted (in %temp%, or
wherever) to either the User, or to the Program which is
writing the redirected/piped output.
(My LOCATE v 3.x [8086 Assembler] does ALL output via
File-Writes [and] can tell when his CON output is redirected
/piped, but NOTHING I/he can test is 100% guaranteed that
he hasn't run out of PipeSpace)-;
(Apparently some DOS's just route any/all pipe overflow to
nul, and give NO error indication whatsoever!!)
Don Hoffman
===============================================================================
48) XCOPY
I'm having a problem. I seem to find that XCOPY does not return
an errorlevel 1 when there are no files to copy. Is this my
imagination or am I doing something wrong?
if errorlevel 1 goto nofiles
if errorlevel 0 goto found
Greg Miskelly
I tested these two error levels using xcopy and it seems that
the errorlevel 0 will work fine if there are files with the
archive attribute set. I removed the archive attribute and I
do not get the errorlevel 1 unless I try to use xcopy on an
"empty" directory and then it becomes the "no files to copy"
errorlevel. Strange or else that is MS DOS's definition of
"no files found to copy". It seems to me that if no files are
"set" for xcopy to copy then there is no errorlevel for that.
Bad news.
Gary E. Brooks
Just discovered something that may help. XCOPY *does* return
an errorlevel of 1 when there are no files to copy. But it
means that there are NO files in the specified directory NOT
that there are no files meeting the specified criteria ie, no
files with the archive attribute set.
Methinks that's its not explained properly in the help file!
John Black
After much experimentation with MSDOS 6.20 (english) and 6.00
(german), I've discovered that XCOPY will return an errorlevel
of 1 only if the source file(s) don't exist.
Up until now I'd assumed, like you, that (with the /m or /a
switch) "No files found to copy" meant "No files with archive
attribute found". Looks like a bug to me. :-(
Since version 6.00, XCOPY will not copy files with the system
or hidden attribute, so it doesn't matter whether the archive
attribute is set or not.
John Evans
With 6.2, I've also experienced some problems with Xcopy
errorlevels. No difficulties with earlier versions, tho.
One bat file in particular really irritated me and I ended
up having to do a work around, because xcopy just wouldn't
cooperate. I suspect there may be a baby bug in v6.2.
Brice Vineyard
Use the following to see if XCOPY is even returning an errorlevel
(I'd almost bet it isn't):
To All - Vernon Supplied a Batch File ERRLVL.BAT to examine errorlevels
returned by programs.
Vernon Frazee
You were right, below is a screen copy of the result:
C:\>errlvl xcopy *.* d:\*.* /m /s
0 file(s) copied
Errorlevel 0
C:\>_
I tested it on a quick format of a write protected double
density diskette, ie:
C:\>errlvl format a: /u /q /f:720 /v:greg
!
(screen garbage deleted for brevity)
!
Errorlevel 4
C:\>_
Greg Miskelly
===============================================================================
49) ZERO-BYTE FLAG FILES
EDITOR'S NOTE: During a discussion about the use of flag files,
Bruce Bowman suggested the following command to produce a zero
byte file:
REM>TEMP$$.DAT
Bruce Bowman
I read in the DOS manual that you are not supposed to use
redirection or pipe commands inside of a batch file. Does
the "REM" nullify this restriction?
Yannick Leclerc
I can't imagine why your DOS manual would say that. I do it
all the time!
The REM command in this case merely creates a zero-byte flag
file called TEMP$$.DAT.
Bruce Bowman
The point is that not many people want 0 byte files on their
h/d so the advice given by the manual is for once spot on.
Ian Underwood
Yes, but what if you DO want one? I use this trick to create
flag files, and have the same batch file delete them later
(as demonstrated). 0-byte files are better for this, since
they take up only the room in the FAT. A 1-byte file takes
up a whole sector.
I don't think the *manual* should say something shouldn't
be done just because some people don't pay attention to what
they do!
Bruce Bowman
Perhaps he may have been thinking of the CALL command, about
which I have seen such a note made in a DOS text:
Note: The CALL command should not be used with piping or
redirection
Bat Lang
Give the man (Yanick Leclerc) a star, he reads the manual! :)
Check that section again, it's not always apparent what they mean
on first reading (a reference manual must be unambiguous; not easy
to follow).
You aren't supposed to redirect or pipe batch files.
ie:
MYBAT.BAT > MY.LOG
or
CRASH.BAT |BURN.BAT
Batch commands can be redirected and piped.
OK.BAT
VER |TIME |FIND "Current" >>BOOT.LOG
Rob Flor
I am in need of updating the time stamps on two 0 byte files.
I tried using " COPY /b F?RESCAN.NOW+,, " as that was the suggested
way to update time stamps, but I guess since they are 0 bytes in
size it just deleted them.
Dennis Morgan
How about using this instead of copy.
REM >>FILENAME.EXT
This still leaves it a 0 byte file but updates the date and time on it.
Tony Baechler
===============================================================================
EDITOR'S NOTE: Also overheard:
There are two entries in the list of commands in IO.SYS that I've
never seen explained: MULTITRACK and FHSTDIC. They're presumably
used in Config.sys.
Shakib Otaqui
In MUF I missed COMMENT (DOS 5 & 6) and MULTITRACK (6).
Richard Pade
EDITOR'S NOTE: In another message from Bill Foster to Chris Kuefler
re: Subj: undocumented DOS commands, the following was overheard...
If you could supply me with a BBS number that has the file online,
or, even better, a BBS that has it available for FREQ it would be
greatly appreciated.
Chris Kuefler
Sure...how about Odyssey Systems - (905) 579-9241 for the
regular BBS lines - located in Oshawa, Ontario.
You can also try Freq'ing DOS56UN.ZIP 21k 01-14-94 from
Odyssey Systems at 1:229/434 - listed nodes only!
Bill Foster
===============================================================================
EDITOR'S NOTE: "Without prejudice" (For any lawyer's out
there). I have not seen the file DOS56UN.ZIP mentioned above, nor
it's contents. However, I have seen at least one hacked version
of the MUF(c) list. I would appreciate it, if the MUF(c) list, as
I have distributed via BatPower, would remain "in it's entirety".
I have noted some magazines, with feature articles including
"hauntingly familiar" information. ;-) The articles mention that
the author has "discovered" a new feature and proceeds to give
several examples of the feature's use, also "hauntingly familiar".
I, for one, would appreciate anyone using the enclosed information
(IMHO, the intellectual property of BatPower), giving credit where
credit is due (as I have attempted to do as your editor for
the past several years). Consequently, I have added the "(c)" to
the introductory screen, and consider the MUF(c) property of
BatPower. If anyone wishes to publish the enclosed information
or the ideas found herein, BatPower would appreciate a mention of
the individuals who have contributed to these "discoveries". A
mention of the MUF(c) list would be nice! ;-)
BatPower, by it's nature cannot claim ownership of these ideas,
and I'm sure they are not all originals, but, BatPower has IMHO
contributed to OUR collective knowledge of the operating system.
It certainly has expanded my knowledge... :-)
Well folks, that's it for Vol.1 #7, and my term as the MUF lists'
editor. MUF Vol. 1 #7 is MY last MUF list, as I am retiring as
the editor. Sorry folks, I have a number of other projects to
conquer. Maintaining the MUF list has taken a good deal of my
time, however, I have found the experience most informative.
I appreciate the interest that the MUF list has generated, and
the knowledge that others have shared with me here in BatPower.
I will continue to be found in BatPower, as long as our local
User's Group is able to maintain a Fido feed... We have been
having a great deal of difficulty doing so since Feb. 27/94
when Net255's satserver went fubar.
Please forward any additional information / retractions / rebuttals
/ comments / error corrections / etc. about these or other Fabulous
MUFs(c) that you may encounter to John Evans.
John has kindly volunteered to continue the tradition as the new
MUF(c) list editor. You may reach John in the FidoNet BatPower echo
or at his origin (2:2433/506). Good Luck John!
Thanks to All for the information! Till next time, (and John's first
list) we return you to our regularly scheduled BatPower program...
--
Yves Bellefeuille
Ottawa, Canada
y...@storm.ca
Francais / English / Esperanto
Pranav Shah
This is a great list! But I have a question: Is this on the net
anywhere? If not, I would be willing to put it on my site. Just tell me
the people that I would have to get permission from to do it, if
he/she/they would let me.
Pranav