How do I boot Ubuntu from a USB on an Acer C720 Chromebook?

Question

I installed Ubuntu using the method described in this video: https://www.youtube.com/watch?v=DMyMqqU2Mqs In short, I installed crouton Ubuntu with the unity interface. and when installing Gimp through the terminal, it deleted a the software center and some other files that may have been important. So when shut down Ubuntu and later tried to get back into it, I couldn't. I learned that I could recover my files by booting Ubuntu using a USB, and my question is how I would do that? Thank you for you help. I only have 3 months of Linux experience, so you might have to talk things out for me.

Answer 1

I learned that I could recover my files by booting Ubuntu using a USB[…]

No!

That's what we get when people are too busy posting videos of the same thing over and over instead of improving the actual documentation and explaining things straight to the point for novice users. But hey, it's way cooler to be an attention whore. (✿◠‿◠)

(Chromebook + crouton + Ubuntu) ≠ (Laptop + Ubuntu)

It's NOT equal, because…

crouton: Chromium OS Universal Chroot Environment

^{The first line in README.md}

…you are using a chroot when using crouton! You are NOT installing Ubuntu as intended using live media or installation media for supported embedded devices.

Accessing files

Accessing your files in the chroot – which is simply speaking just an isolated part of the filesystem – should be easy if you know where it resides in the filesystem. It's usually /var/chroot/, but this may not be true for Chrome OS or crouton. On the other hand you would face the same problem when probably successfully booting live media on the Chromebook and eventually accessing the Chrome OS data partitions.

Backing up files

If you have trouble finding the location, but still know how to use crouton to manage your chroots, the following part from the README.md will generate a .tar.gz with all of your data and the chroot OS data, that you could browse with file-roller or any other archive manager.

A backup a day keeps the price-gouging data restoration services away

1. sudo edit-chroot -b chrootname backs up your chroot to a timestamped tarball in the current directory. Chroots are named either via the -n parameter when created or by the release name if -n was not specified.
2. […]

By the way, it's not the author or contributors fault. They did a good job by making this tool available. It's everyone else's fault for doing such a poor job explaining what a chroot (on Linux) is and what the result will be when you install Ubuntu on a Chromebook this way. (Something that looks like Ubuntu, but isn't supported by anyone and you as a user shut yourself out of what you thought was your hardware. It's Google's hardware, you're just allowed to use it.)

APT logs and history

[…] and when installing Gimp through the terminal, it deleted a the software center and some other files that may have been important.

Definitely not. Just installing Gimp on a supported installation through terminal or software center is completely safe and shouldn't uninstall critical components or make the system unstable in anyway.

You can look at the histroy of installed, uninstalled and updated packages with:

zless /var/log/apt/history.log

Of course the path is from inside the running OS or chroot (should be /var/chroot/my_chrooted_ubuntu/var/log/apt/history.log). Older logs have the following scheme : history.log.1.gz. You can leave the zless program by typing q.