Good

~/.tmux.conf

set -g exit-empty off
bind-key v split-window -h
bind-key s split-window -v
bind-key h select-pane -L
bind-key j select-pane -D
bind-key k select-pane -U
bind-key l select-pane -R

~/.bashrc

if [[ -z $TMUX ]]; then
	ID=$(tmux list-session | grep -vm1 attached | cut -d ':' -f 1)
	if [[ -z $ID ]]; then
		tmux -2 new-session
	else
		tmux -2 attach-session -t $ID
	fi
fi