Auto-attach to most recent tmux session on ssh

.bashrc

# Auto-attach to most recently used tmux session on SSH login, or start fresh
if [[ -n "$SSH_CONNECTION" && -z "$TMUX" ]]; then
    last_session=$(tmux list-sessions -F "#{session_last_attached}|#{session_name}" 2>/dev/null | sort -rn | head -1 | cut -d'|' -f2)
    if [[ -n "$last_session" ]] && tmux has-session -t "$last_session" 2>/dev/null; then
        exec tmux attach-session -t "$last_session" 2>/dev/null || exec bash
    else
        exec tmux 2>/dev/null || exec bash
    fi
fi

.tmux.conf

# Exit shell when tmux exits
set-option -g exit-empty on