How to map Alt-Enter

Question

I'm using gnome-terminal, which uses 7-bit input. This means Vim's meta/alt keys, e.g. <M-f> don't work without some extra configuration. I know how to set that up for normal keys, like F, but not for Enter.

When I press Alt+F the terminal sends ^[ F, where the ^[ is a single Escape byte (\x1b). I can make <M-f> usable by doing:

set  <F13>=^[f
map  <F13> <M-f>
map! <F13> <M-f>

How can I do this for the Enter key (<CR>)?

Answer 1

On many terminals (specifically the ones that send alt-modified keys as escape then key), you can map alt+enter in the same way as many other alt combinations,

set <a-cr>=^[^M

This is two characters- escape then control m. Alternatively,

execute "set <a-cr>=\<esc>\<cr>"

Then you can then use <a-cr> in maps;

nnoremap <a-cr> something

There is no standard way to map alt+shift+enter, or indeed any other alt+shift+ combination. Also, if your terminal supports it, you will have to use one of the unused F keys, e.g. <f13> through <f37> on linux (since there's no <s-c-cr> key code in vim) set to your terminal's proprietary escape sequence.

set <f25>=...

For example, my terminal sends escape, escape, then OM (four characters):

set <f25>=^[^[OM