This batch file should do it for you.
Copy the batch file below into a text file and save it as xrename.cmd (or "whatever you want.cmd").
If you just run the file like this:
xrename.cmd
It will look in the current folder and all subfolders, and rename all files like: ABC12345_DEF to ABC12345.DEF (anything like "text_moretext" to "text.moretext").
You can also provide values for "search-string", "replace-string", and "search-pattern" on the command line.
To show instructions, run it like this:
xrename.cmd /help
Note: I made the batch file to only display the files that will be renamed, no renaming will actually take place. You can run the batch file and see what will happen without actually renaming anything. Once you have run it and are confident the correct files will be properly renamed, you can delete the line as described below to make renaming active, then run the batch file again.
You might have to modify the value of "search-pattern" to display the files you want.
At the labels ":default1" and ":default2", you can edit the values for "match-string" "search-pattern" and "replace-string" to suit your needs.
This batch file has some error checking and it won't fail if the "match-string" is found in the names of any of the folders or subfolders.
@echo off if "%~1%~2%~3."=="." goto :default1 if /i "%~1."=="/help." goto :syntax if "%~1."=="." goto :syntax rem %2 can be empty to use "*matchstring*" as the "search-pattern" rem %3 can be empty to make replacement with empty string (delete matchstring). set "matchstring=%~1" set "replacestring=%~3" if "%~2."=="." goto :default2 set "searchpattern=%~2" goto :start :default1 set "matchstring=_" set "replacestring=." :default2 set "searchpattern=*%matchstring%*" :start set "renamecount=0" set "errorcount=0" echo. for /r %%f in ("%searchpattern%") do call :work "%%~dpf" "%%~nxf" echo. if %renamecount% EQU 0 echo No files renamed. if %renamecount% EQU 1 echo Renamed %renamecount% file. if %renamecount% GEQ 2 echo Renamed %renamecount% files. if %errorcount% EQU 1 echo %errorcount% error renaming files. if %errorcount% GEQ 2 echo %errorcount% errors renaming files. echo. goto :cleanexit :work set matchedfilepath=%~1 set matchedfilename=%~2 rem You can't do it directly like this: rem set "newfilename=%matchedfilename:%matchstring%=%replacestring%%" for /F "usebackq delims=" %%g in (`echo set "newfilename=%%matchedfilename:%matchstring%=%replacestring%%%"`) do %%g echo In path "%matchedfilepath%": Renaming "%matchedfilename%" to "%newfilename%" rem delete the next line (goto :EOF) to make renaming active goto :EOF ren "%matchedfilepath%%matchedfilename%" "%newfilename%" if %errorlevel% NEQ 0 goto :workerror if not exist "%matchedfilepath%%newfilename%" goto :workerror goto :workok :workerror echo Rename "%matchedfilepath%%matchedfilename%" failed. set /A errorcount=errorcount+1 echo. goto :EOF :workok set /A renamecount=renamecount+1 goto :EOF :syntax rem:syntax echo. echo Syntax: echo %~nx0 ["match-string" ["search-pattern"] ["replace-string"]] echo. echo Search for files matching "search-pattern" in current folder and through all echo subfolders. For each matched file, rename file by replacing "match-string" echo with "replace-string". echo. echo If "replace-string" is empty or not specified, rename file by deleting echo "match-string". echo. echo If "search-pattern" is empty, use "*matchstring*" as the "search-pattern". echo. echo If "match-string" "search-pattern" and "replace-string" are all empty or not echo specified, then defined defaults will be used. echo. echo If "search-pattern" and/or "replace-string" are NOT empty then "match-string" echo cannot be empty, echo. goto :EOF :cleanexit set "matchstring=" set "replacestring=" set "searchpattern=" set "renamecount=" set "errorcount=" set "matchedfilepath=" set "matchedfilename=" set "newfilename=" goto :EOF Once you have run the batch file and are confident the correct files will be properly renamed, you can edit the file to remove the line(s) described to make renaming active, then run the batch file again.
To do that, find the two lines that are like this:
rem delete the next line (goto :EOF) to make renaming active goto :EOF Then, remove the line that says "goto :EOF" (or remove both lines).
Don't remove "goto :EOF" from any other place in the batch file (it can be found in a few places so be sure to remove the correct one).
If this isn't working for you, or if you want me to explain anything in the batch file, just let me know.