so on most of my machines i have mrxvt to be my primary term in evilwm. every time i do the term hotkey i want a new session of tmux to start up without attaching to a previous / existing session.

here is what i added in my .bashrc to make this happen:

tmux_count=`tmux ls | wc -l`
if [[ "$tmux_count" == "0" ]]; then
    tmux -2
else
    if [[ -z "$TMUX" ]]; then
        if [[ "$tmux_count" == "1" ]]; then
            session_id=1
        else
            session_id=`echo $tmux_count`
        fi
    tmux new-session -d -s $session_id
    tmux attach-session -t $session_id
    fi
fi

this snippit will also increase your tmux session id’s by one each time and not attach to an existing session id.