If I may... I think the following may be helpful here, possibly good to put into two reserved posts, I've separated them with ~ characters. Cheers!
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Can I use an existing Ubuntu/Linux setup?
Yes, providing it's within spec.
Various Linux distributions vary a little on their support libraries, so it will have to be Ubuntu 12.04 or above.
As memory serves, some of the Unlimited tools for other phones will accommodate 64-bit Ubuntu if you add some 32-bit libraries but
not Juopunut.
So, the other machine has to be 32-bit Ubuntu as specified.
How to tell if you have 32-bit Ubuntu -
Enter the following command in the terminal window:
uname -a
If you see x86_64 in the return, it's 64-bit, if you don't, it's 32-bit.
If you don't see Ubuntu in the return, it's not a supported machine.
How to check which version you are running -
Enter the following command in the terminal window:
lsb_release -a
The banner output is user friendly, the revision is clearly marked.
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How do I get out of Linux?
To reboot your PC, enter the following in the terminal command window -
shutdown -r now
To halt your PC instead, enter -
shutdown -h now
Most people will want to use the first command and reboot back into Windows.