Detect background vim after :sh

Question

I often use the :sh command while using vim (to do a grep for example).

But sometimes I forgot I had a vim running behind my shell.

Is there a command to detect that I have a vim running behind my shell?

Answer 1

You can see if Vim-specific shell variables are set:

$ echo $VIM
$ echo $VIMRUNTIME
$ echo $MYVIMRC