Rename all files from one extension to another using DOS command line

I was looking for a fast way of massively renaming files from one extension to another. Apparently, DOS command line was pretty handy solving this issue.

For example, in order to rename all the files with extension “jpg” to “test” on the directory named “C:\My Pics” you should do:

ren "C:\My Pics\*.jpg" *.test

This is how it looks on the DOS command line: