This is much better:

    echo -n "$(diceware -d '-' -n 3)"$(( RANDOM % 10 )) | xsel -b

It copies passwords like `Uncertain-Postbox-Cannot5` to your clipboard. Much easier to remember/type, and just as secure. I've assigned that to a hotkey, so whenever I need a password I press Super+G, Ctrl+V, and that's it.