lapse:~> 7zr a -so somedir > myarchive.not7z

7-Zip (A) 4.43 beta  Copyright (c) 1999-2006 Igor Pavlov  2006-09-15
p7zip Version 4.43 (locale=en_GB.UTF-8,Utf16=on,HugeFiles=on,1 CPU)


Error:
there is no such archive

Of course there isn't, I want to create it that way. Simply because
I need to write to a tempfile, which does not have a .7z extension,
so I cannot pass it on the command line, because 7zr will then
simply add .7z to the end, causing a potential security hole (race
condition).