[SLUG] treating \n like any other character

[david <david@xxxxxxxxxxxxx>]

I want to edit a multi line file as if it were all one line 

In other words, treat \n like any other character, and specifically
doing global find and replace.

I know there are various hex editors, but they are all pretty clunky as
far as I can see, and none seem to be able to do that from command line.

Is there a shell script way to do it?