How to add and remove postfix for all files in folder using BATCH File

Question

I'm trying to add and remove postfix from specific file types in all folders and subfolder.
I know the code for adding prefix but I don't know the code for postfix

Here is my code for prefix

Adding PreFix:

@echo off
pushd "D:\Temp\Test\"
for /F "delims=" %%j in ('dir /s /b *.avi *.mkv *.mp4 *.wmv *.mpeg *.flv *.dat *.mov *.asf *.3gp *.srt') do (
   rename "%%j" "[my.prefix]-%%~nxj"
)
popd

Removing PreFix:

@echo off
pushd "D:\Temp\Test\"
for /F "delims=" %%a in ('dir /s /b *.avi *.mkv *.mp4 *.wmv *.mpeg *.flv *.dat *.mov *.asf *.3gp *.srt') do (
    set "fname=%%~nxa"
    set "fpath=%%~dpa"
    setlocal enabledelayedexpansion
    set "nname=!fname:~15!"
    ren "!fpath!!fname!" "!nname!"
    endlocal
)
popd

How to do this for postfix?

Answer 1

Add suffix

@echo off
pushd "D:\Temp\Test\"
for /F "delims=" %%j in ('dir /s /b *.avi *.mkv *.mp4 *.wmv *.mpeg *.flv *.dat *.mov *.asf *.3gp *.srt') do (
   rename "%%j" "%%~nj-[my.suffix]%%~xj"
)
popd

Remove suffix

@echo off
pushd "D:\Temp\Test\"
for /F "delims=" %%a in ('dir /s /b *.avi *.mkv *.mp4 *.wmv *.mpeg *.flv *.dat *.mov *.asf *.3gp *.srt') do (
    set "fname=%%~nxa"
    setlocal enabledelayedexpansion
    set "nname=!fname:-[my.suffix]=!"
    ren "%%a" "!nname!"
    endlocal
)
popd

Answer 2

set fileName=thisIsATest_0001
set fileExtension=.avi

echo %fileName:~0,-5%%fileExtension%

Negative values in second part of substring indicate distance from end of string