Mass rename of file extensions recursively (windows batch)

Question

I have numerous files in a very complex directory structure, and for reasons not worth discussing I need to rename all files with the extension of \".inp\" to have \".TXT\" exte

Answer 1

On Windows 7, the following one-line command works for me, to rename all files, recursively, in *.js to *.txt:

FOR /R %x IN (*.js) DO ren "%x" *.txt