Fastest way to change multiple file extension without external software

1. Create a 'Text Document.txt' file in the folder you want to change file extensions.

2. Open the text doc. you just created and type following command.

REN *.(old extension) *(new extension)

example:

REN *.m4a *m4b

3. Close the text doc. and change the '.txt' extension to '.cmd' and double click on the file.

4. You'll see the changed file extensions.

pretty sweet ahy~