Expanding arbitrary variable to a drive, path etc. in a DOS batch

Question

Hi.

I am using a dos batch which processes file using passed parameter:

process.bat "D:\PROJECT\TEST FILES\test.pdf" 72

process.bat:

gswin32c -r%2 -sDEVICE=jpeg -sOutputFile="%~n1-%%d.jpg" -- "%~1"

We can see that the parameter is expanded to the file name in the batch: %~n1. However I was asked to rewrite the batch to read parameters from a text file:

params.txt

1 D:\PROJECT\TEST FILES\test.pdf
2 72

So I have modified the process.bat:

for /f "tokens=1,*" %%A in ('type ..\params.txt') do set P%%A=%%B
gswin32c -r%P1% -sDEVICE=jpeg -sOutputFile="%~nP2%-%%d.jpg" -- "%~1"

But %~nP2% doesn't work.

I have found that for /f "tokens=*" %%A in (%P1%) do %%~dA could help me but it looks cumbersome.

So is there any other way to expand arbitrary variable to a name, drive, path etc.?

Answer 1

Yeah, those only work with the special number-based arguments. But you can turn your variable into one by passing it to a subroutine in the batch file. Example:

@echo off
set P1=D:\PROJECT\TEST FILES\test.pdf
call :Split %P1%
echo %FNAME%
exit /b 0

:Split
set FNAME=%~n1
exit /b 0

...prints "TEST" (the name part of test.pdf)