This batch script will do it.
if "%target%"=="" set target=%cd%
rem Previous two lines deliberately left blank for LF to work.
for /f "tokens=*" %%i in ('dir /b /s /a:-d "%target%"') do (
if "!ext!"=="" set ext=FileWithNoExtension
echo !extlist! | find "!ext!" > nul
if not !ERRORLEVEL! == 0 set extlist=!extlist!!ext!:
Save it as any
.bat file, and run it with the command
batchfile (substitute whatever you named it) to list the current directory, or specify a path with
batchfile "path". It will search all subdirectories.
If you want to export to a file, use
batchfile >filename.txt (or
batchfile "path" >filename.txt).
Everything before the
for /f... line just sets things up: it gets the target directory to search, sets delayed expansion which lets me do some magic with the variables in the loop and defines a newline (
LF) that I can use for neater output.
The loop uses that
dir /b /s /a:-d "%target%" command, grabbing a list of all files in all subdirectories under the target.
%%~xi extracts the extension out of the full paths the
dir command returns.
An empty extension is replaced with "FileWithNoExtension", so you know there is such a file - if I added an empty line instead, it's not quite as obvious.
The whole current list if sent through a
find command, to ensure uniqueness. The output of the find command is sent to
nul, essentially a black hole - we don't want it.
%ERRORLEVEL% is set by the
find command, a value of 0 indicates there was a match. So if it's not 0, the current extension is not on the list so far and should be added.
The echo line basically outputs, and I also replace my placeholders (
:) with newlines to make it look nice.