Batch Script GPG Decryption

The following should work:

@ECHO off
SET password=correcthorsebatterystaple
PUSHD "C:\encrypted files"
FOR /F "tokens=*" %%F IN ('DIR *.gpg /B') DO (
    gpg --output %%~nF --batch --yes --passphrase %password% --decrypt %%F)
POPD

      

        
        
        
      

    

Explanation:

• PUSHD
  
  and POPD
  
  are used for temporary maneuver to another directory;
• there is no temporary text file needed to store the output DIR
  
  , because it is FOR
  
  also capable of parsing the output of a command (the set is internally IN ()
  
  enclosed in ''
  
  , so it is interpreted as a command, not a file specification.);
• to truncate the file extension (which you want to do with the second temp file and the inner loop FOR
  
  , at least according to my interpretation), you just need to specify a modifier ~n
  
  , in our situation %%~nF
  
  ; your method doesn't work because:
  • you cannot do inline math calculations as you tried namelen-4
    
    (you will need to use an intermediate variable together with SET /A
    
    for arithmetic operations, and also deferred expansion should have been active then);
  • type substring expansion :~0,8
    
    does not work with variables FOR
    
    (you need an intermediate variable for this, and again deferred expansion should be active then);

Addition
If the script has problems with spaces in the input filenames, you may need to swap the command line gpg

with this:

gpg --output "%%~nF" --batch --yes --passphrase %password% --decrypt "%%~F"

      

        
        
        
      

    

Modifiers ~

remove potential surrounding double quotes, so "%%~nF"

they "%%~F"

always enclose the filename with double quotes. Note that it "%%F"

can inadvertently result in double quotes ...