Keeping track of Vim nesting

.bashvimrc.sh

# This file is loaded by vim when calling :sh
# The purpose of this file is to set up PS1 to show that you are in a shell
# opened by vim.

source ~/.bashrc
export VIMEXTRA=''
if [[ -z "$VIMSHELL" ]]; then
    export VIMSHELL=1
else
    export VIMSHELL=`expr $VIMSHELL + 1`
    export VIMEXTRA=" x$VIMSHELL"
fi

# expecting something like "Attila@Attila-PC:~/.vim (vim) (master *=)$" if within vimshell
# and expecting "Attila@Attila-PC:~/.vim (vim x2) (master *=)$" if in a vimshell within a vimshell
PS1="\u@\h:\w \[\033[01;31m\](vim$VIMEXTRA)\[\033[01;34m\]\[\033[01;33m\]\$(__git_ps1)\[\033[00m\]\$ "
# vim: set filetype=sh :

escape $(__git_ps1) so that it would be resolved on each shell prompt, instead of caching the result.