On Tue, 15 May 2018, Jaap Akkerhuis wrote:

> Early unixes had dsw: Delete by SWitch register.

Needed because the file system was then so !@#›%-up that "rm" wouldn't 
work, so the i-number had to be keyed in.

It was also known as Delete Sh*t Work :-)

I think that "clri" was written shortly thereafterwards; I have a paper on 
its use somewhere in the archives, from around the 70-80s.

-- Dave