Convert long filename to short filename (8.3) using cmd.exe

Question

I am trying to convert a long filename to a short filename (8.3) on Windows.

A batch-file with a command line argument works as intended:

short.bat :

@echo OFF
echo %~s1

calling short.bat C:\\Documents and Settings\\User\\NTUSER.DAT returns C:\\DOCUM~1\\USER\\NTUSER.DAT

However, I don't like having an extra .bat-file for this. I would rather call cmd.exe with the whole command from a ruby script. How can I do this?

As an intermediate step I tried to hardcode the path in the batch-file, but that does not work:

short1.bat :

@echo OFF
SET filename="C:\Documents and Settings\User\NTUSER.DAT"
echo %filename%
echo %~sfilename%

echo %filename% works, but echo %~sfilename% gives the following error:

The following usage of the path operator in batch-parameter
substitution is invalid: %~sfilename%

For valid formats type CALL /? or FOR /?

If short1.bat works, how can I convert this into a one-liner that can be called with cmd.exe \\c ... ?

There is another question ( how to get DOS path instead of Windows path ), however that one is specifically asking for the path of the current directory.

Answer 1

cmd /c for %A in ("C:\Documents and Settings\User\NTUSER.DAT") do @echo %~sA

Answer 2

Replace the filename.txt to the filename you want to convert to 8.3

dir /x filename.txt

You will then have to split the result with whitespace as your delimiter (\\s in regex). Then the value with the ~ is your short filename. If your filename is short to begin with, then you won't find a string containing a ~.

Answer 3

Here is an example that read in the registry the location of your "appdata\\local" folder and convert it to short path:

cls
@echo off
cd /d "%~dp0"
chcp 65001 >nul

for /f "skip=1" %%a in ('"wmic useraccount where name='%USERNAME%' get sid"') do (
    for %%b in (%%a) do set current_SID=%%b
)
set current_username=%USERNAME%
set current_userprofile=%USERPROFILE%

set key_to_read=HKEY_USERS\%current_SID%\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders
set value_to_read=Local AppData
rem If value_to_read contains ? space(s) set tokens to 2+?
for /f "usebackq eol= tokens=3,* delims= " %%a in (`reg query "%key_to_read%" /v "%value_to_read%" 2^>nul ^| find "%value_to_read%"`) do (
    set value_type=%%a
    set data_read=%%b
)
set data_read=%data_read:USERPROFILE=current_userprofile%
call set "data_read=%data_read%"
set current_local_appdata=%data_read%

set current_local_appdata_temp=%current_local_appdata%\Temp
echo %current_local_appdata_temp%

for %%a in ("%current_local_appdata_temp%") do set "current_local_appdata_temp_short=%%~sa"
echo %current_local_appdata_temp_short%

pause
exit