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Number   :  4750
Date     :  2003-06-04
Author   :  Garry Deane
Subject  :  Re: xxcopy to CD-RW
Size(KB) :  3


--- In xxcopy@yahoogroups.com, Kan Yabumoto  wrote:

> The code you suggested earlier is quite sufficient
> in my view. The "problem" you are trying to address
> by the much longer script is a result of totally
> unreasonable operation on users part. If the
> user has no idea what the PATH= setting does,
> there is no hope that he can manage executing
> the proper copy of the XXCOPY.EXE file.

I tend to agree. I would expect that new users will
double click on INSTALL.BAT and experienced users will
CD to the appropriate directory or specify the path.

> I'm always amazed that people like you can create
> a bullet-proof batch script like that.

As it turned out, I was able to "break" it by creating
a path which included an un-quoted directory with a space
in it. I think this is illegal in W9x but is legal in
NT/W2k/XP. If the %OS% variable is altered for whatever
reason, the code will go into an infinite loop.

If anyone is following this thread and is interested, the
code snippet after :chkpath should be changed to:

:: Search for this batch file in the path
:ckpath
set rec=
if exist %1.\%src% goto found
shift
if "%1"=="" goto :notfound
goto :ckpath
:found

> One solution is to provide a more unique name
> than "INSTALL.BAT". But then, typical (experienced)
> user would have hard time guessing which one in the
> unzipped files in the temporary directory.
> 
> As I said earlier, the solution should be fairly
> "elegant". Although the new and much longer version
> may close the hole for the rare case, the sheer
> length alone disqualifies itself. That is,
> I have hard time following the batch script
> (mostly my lack of mental energy to fully
> comprehend what is going on in the batch file).
> When, the script become too long, it would be
> understood only by a very few advanced users only.
> 
> One benefit of the batch file is that it is a
> "well-understood" rules which most people can
> follow by just looking at it. When the required
> action for the very rare cases makes the batch
> file much longer, then, the benefit evaporates.

Yes I agree. I just wasn't sure whether you wanted to
eliminate a source of potential trouble or at least know
abot it. The difficulty of course is that when the batch
is complex, remotely troubleshooting a failed run with an
inexperienced user can become a nightmare. KISS still
works well.

> So, I'm just about ready to incorporate your
> first suggestion (which is very elegant and works
> well). I'm thinking about putting a text which
> gives you the credit for the code if you don't
> mind (If you have objection, I will not put your
> name in it). The first section of the batch
> file will look like this:



No I don't really want any credit since the NT/W2k/XP method
is fairly commonly known and the credit for the DOS/W9x
method belongs to others.

I would suggest however that the NT/W2k/XP line is changed to:

if "%OS%"=="Windows_NT" ((cd /d %~dp0)&(goto next))

This is slightly more obvious, is documented (see call /?),
is bullet-proof and should survive any potential future
changes to CMD.EXE

I also recommend that you leave the "if not exist install.bat
goto error1" test and error message in place in case it does
break.

> Again, thank you for your great help.

A pleasure to contribute in a small way to a great program.

Garry



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