start new:

    $ tmux


start new with session name:

    $ tmux new -s myname


attach:

    $ tmux a  #  (or at, or attach)


attach to named:

    $ tmux a -t myname


list sessions:

    $ tmux ls


kill session: 

    $ tmux kill-session -t session_name


Kill all the tmux sessions:

    $ tmux ls | grep : | cut -d. -f1 | awk '{print substr($1, 0, length($1)-1)}' | xargs kill