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Number   :  343
Date     :  2001-07-06
Author   :  Joseph Maddison
Subject  :  Re: Question for DOS Gurus
Size(KB) :  1


Thank you for the code. This works really well. 
> I do not understand the statement that reads 
>         echo set v=%%4>%winbootdir%\volume.bat

The line that begins " Volume Serial Number is " is piped to temp.bat
and executed. When it executes, it tries to run a program called
'volume'. Since there's a Volume.bat in the directory, it is executed.
%4 is parameter #4, the word after "is" on the command line. It's
an interesting little batch file (and took me a while to decode).

> Why do we need the echo? Why %%4? The volume.bat file seems empty!

%% converts to % during batch execution, so this becomes set v=%4
inside volume.bat. 

Here's the script, revised to work under NT4, which has no vol 
command. A Dir works just as well. the 2>nul pipes the "File
Not Found" to the null device to avoid printing an error.

@echo off
:: Extracts serial number to use in renaming a log file
:: tested in WinNT4
dir \_nofile_at_all 2>nul | find " Volume Serial Number is" >%TEMP%\temp.bat
echo set v=%%4>%TEMP%\volume.bat
call %TEMP%\temp.bat
:: temp.bat calls volume.bat indirectly
del %TEMP%\temp.bat
del %TEMP%\volume.bat
echo The serial number of the current drive is %v%
ren xxcopy.log %v%.log
set v=

_nofile_at_all is just a file that does not exist.

Regards,

Joseph Maddison
Minneapolis, MN



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