I\'m running Vim on a gnome terminal. But the alt key mappings are not working.
For example (this is just an example):
:imap
Take a look at section 1.10 of http://vimdoc.sourceforge.net/htmldoc/map.html. It seems to indicate that gnome-terminal automatically escapes the Alt modifier, so that it doesn't switch the byte sent in the way that Vim is expecting. The document seems to indicate that there isn't really a way around this except for using a different terminal (such as xterm).
This is certainly frustrating because so far as I can tell Linux machines are also incapable of using the D (Mac's Command or Linux's Super) bindings, so at least as far as the terminal goes, we are limited to Shift and Ctrl modifiers, which is frustrating if we want to ensure that we can use all the commands we use in Gvim on terminal Vim (at least without switching terminals, towards which I'm perhaps overly stubborn - gnome-terminal is just so much prettier). I've been looking for a way around this but have been unable to find anything.