How to rename 80.000 files at once in Windows

Here's a way using PowerShell:

Navigate to your folder and run this command

Get-ChildItem *.jpg | Rename-Item -newname {"._" + $_.Name}

Extra bonus short version:

gci *.jpg | ren -newname {"._" + $_.Name}

I have 2 solutions:

1. All files are in the same folder

   • run the following from command prompt on that folder:

     for /f "delims=¯" %i in ('dir /b /on') do ren "%i" "._%i"
     

2. complete solution when there are files in subfolders AND when you wanna to replace the "n" first characters with a string you want :D

   • create a batch file with the following command
   • change variable parameters to what you want
     • path: put inside "" the root path of your files (e.g. "C:\documents and settings\user\desktop\new folder"
     • numfirstchars2replace: put a number with the first characters to replace (in your case, 2)
     • str2put: put a string to be added as a prefix of the new filename (in your case, ._)
   • run it in a folder different from where the files are

@echo off

::only to tell user what this bat are doing
echo.1.initializing...

::enable that thing to allow, for example, incremental counter in a for loop :)
echo.- EnableDelayedExpansion
SETLOCAL EnableDelayedExpansion

::variables
echo.- variables
:: - place here the absolute root path of your files
set path="put here where are the root folder of your files"
set pathbak=%cd%
set numfirstchars2replace=2
set str2put=._

::go to %path% and its driveletter
echo.- entering the path you want
for /f "delims=¯" %%i in ('echo.%path%') do %%~di
cd %path%

::search all subfolders and save them to a temp file
echo.- searching for subfolders
echo.%path%>%temp%\tmpvar.txt
for /f "delims=¯" %%i in ('dir /s /b /on /ad') do echo."%%i">>%temp%\tmpvar.txt

::execute command for root folder and all found subfolders
echo.
echo.2.executing...
for /f "delims=¯" %%i in (%temp%\tmpvar.txt) do (
  cd %%i
  echo.- in folder: %%i
  for /f "delims=¯" %%j in ('dir /b /on /a-d') do (
    set newname=%%j
    set newname=!newname:~%numfirstchars2replace%,1000!
    echo.- renaming from "%%j" to "%str2put%!newname!"...
    ren "%%j" "%str2put%!newname!"
  )
)

echo.
echo.3.exiting...
::return to %pathbak% and its driveletter
for /f "delims=¯" %%i in ('echo.%pathbak%') do %%~di
cd %pathbak%

@echo on

If they are all in the same folder, you could select them all with Control + A and then hit F2 to rename one of them. All subsequent files will be named file(2), file(3), etc