Rename files having no extension

Question

How can we rename all files in a folder having no extension at all to ".something". I have tried ren *.* *.jpeg and few more but nothing working

Answer 1

* matches any extension. You want to match no extension, so don't supply one: ren *. *.jpeg.

The above only works in cmd -- PowerShell's wildcards work differently, and mostly don't do anything special with extensions. What's more, batch renaming in PowerShell works differently. So:

dir -Filter "*." -File | ren -NewName { $_.name -replace "$", ".jpeg" }