tmux

    Ctrl+b " — split pane horizontally.
    Ctrl+b % — split pane vertically.
    Ctrl+b arrow key — switch pane.
    Hold Ctrl+b, don’t release it and hold one of the arrow keys — resize pane.
    Ctrl+b c — (c)reate a new window.
    Ctrl+b n — move to the (n)ext window.
    Ctrl+b p — move to the (p)revious window.
To close a single pane in tmux, you need to either press Ctrl+d or type exit and press Return.