Nested loop in BAT file (batch) returning undesired results

Question

I have the following code. It works great except for a couple issues. First, my "if not blank" check doesn't work at all. Second, during each iteration, the last time it passes the servername as both the servername and folder, which I'm really not understanding...

code

 SET servers=server01,server02
 SET drive=c
 SET root=program files (x86)\test\
 SET backup=%root%\backup 
 SET folders=folder01\,folder02\file01.txt


 FOR %%b in (%servers%) do (
    FOR %%a in (%folders% %%b) DO (
        if not %%a == "" call :backup %%b %%a
    )
 )


:backup
 SET currentfile="\\%1\%drive%$\%2"
 setlocal
 echo Backing Up %currentfile%
 REM mkdir "\\%1\%drive%$\%backup%"
 REM xcopy /I
 exit /b
 endlocal
 goto :end

output

1] Backing Up "\\server01\c$\folder01\"
2] Backing Up "\\server01\c$\folder02\file01.txt"
3] Backing Up "\\server01\c$\server01"
4] Backing Up "\\server02\c$\folder01\"
5] Backing Up "\\server02\c$\folder02\file01.txt"
6] Backing Up "\\server02\c$\server02"
7] Backing Up "\\\c$\"

As you can see, lines 3, 6 and 7 are not desired.

Answer 1

Lines 3 and 6 are caused because of the %%b in the inner for loop. Line 7 is caused because the script does not terminate after the loops, so it runs the :backup code once more at the end.

The following seems to give the desired result:

@echo off

SET servers=server01,server02
SET drive=c
SET root=program files (x86)\test\
SET backup=%root%\backup 
SET folders=folder01\,folder02\file01.txt


FOR %%b in (%servers%) do (
    FOR %%a in (%folders%) DO (
        rem echo a is %%a
        if not %%a == "" call :backup %%b %%a
    )
)

exit /b


:backup
SET currentfile="\\%1\%drive%$\%2"
setlocal
echo Backing Up %currentfile%
REM mkdir "\\%1\%drive%$\%backup%"
REM xcopy /I
endlocal