How to replace all spaces by underscores in all file names of a folder?

Question

I\'m trying to rename all the files inside a folder (all .exe files). I want to replace all the spaces with underscores, e.g. qwe qwe qwe asd.exe to qwe_q

Answer 1

Simple as:

set filename=qwe qwe qwe asd.exe
set filename=%filename: =_%