QEMU lets you emulate a machine —in other words, you can run a virtual computer on top of your real computer. This makes it perfect for trying and testing the latest release of a distribution, running older operating systems, or just testing.

So, let’s say you wanted to run a LiveCD, which you have stored on your hard drive. Easy enough! We just type:

qemu -cdrom path/to/livecd.iso -boot d

The -cdrom option tells QEMU the path to the CD you want to use, while -boot dictates what device we’re booting from —in this case, we want to boot from the CD, which is always device d.

You might get a message about kqemu —you can safely ignore this for now.

Alternatively, you may want to boot from a real CD in your computer —so, you simply use the path to your CD drive in /dev. For instance, if your CD drive is /dev/hdc, then we would use:

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