Why shouldn't ^J (linefeed) be used as a command in an application?

[Guy Harris]

>What are the historical or cultural reasons that ^J is not used in UNIX
>tools?

There *are* UNIX cbreak-mode or raw-mode applications that use ^J and ^M
for different purposes; some versions of EMACS do (but then again they
permit you to do fairly arbitrary key bindings).  The main problem is if
you have a terminal that can't send them both, but that's a different
matter.