Extract the result of a shell command to a variable in a .vimrc file?

Question

In my .vimrc file, I would like to store in a variable the result of an external command, in my case:

$ echo $LANG

So that my .vimrc file would have :

let language = output(!echo $LANG)
if language == 'en'
   nnoremap <somekey> <ohanotherkey!>
end if

So far I couldn't find how to do it. I've found that in command mode, :read !echo $LANG would insert in my current file the content I am looking for. But I don't know how to write it down in a .vimrc file.

Answer 1

You can do this with the system function:

let language = system('echo $LANG')

Bonus point: if your output is a list, you can use the systemlist instead to get back a list. e.g.

let files = systemlist('ls')
" ['bin', 'dev', ... ]

ref: :h system

Answer 2

If LANG is an environment variable you can just do:

let language = $LANG

Or, even simpler:

if $LANG == 'en'
…
endif