Mac users used to use the thumb for command key We press a thousand command – combinations a day. On windows and unix world, the control key combination is a big non-used to for Mac users. On Ubuntu, it is easy to switch the position of Ctrl key with the Alt key… where on some keyboard the Alt is at the position where the Mac command key is positioned. go to system settings /  keyboard / there are options to swap the ctrl key with alt key. Have fun.  

By michael