In my previous experiences installing ubuntu from a live*, there always was some 'install'-icon at the desktop. Right now, I'm trying to install Ubuntu from a liveUSB, which does not supply such an icon.

Is there any way I can install from the commandline or at startup?

I get a text-prompt for choosing the kernel image to load at startup, with afaik 3 choices (booting the liveCD, doing a checksum or checking the memory)