Mac + Virtualbox/Linux ALT=CMD

By default it seems that when you run Linux in Virtualbox on a Mac, ALT will be mapped to the OPTION key and SUPER will be mapped to CMD.

It's much more natural to swap these, i.e. to map ALT to CMD.

And here's how you do it:

Create ~/.Xmodmap containing...

clear mod1
clear mod4

keycode 133 = Alt_L NoSymbol Alt_L
keycode 64 = Super_L NoSymbol Super_L

add mod1 = Alt_L
add mod4 = Super_L

And then

$ xmodmap ~/.Xmodmap

Enjoy!