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crouton

by dnschneid

dnschneid /crouton

Chromium OS Universal Chroot Environment

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crouton: Chromium OS Universal Chroot Environment

crouton is a set of scripts that bundle up into an easy-to-use, Chromium OS-centric chroot generator. Currently Ubuntu and Debian are supported (using debootstrap behind the scenes), but "Chromium OS Debian, Ubuntu, and Probably Other Distros Eventually Chroot Environment" doesn't acronymize as well (crodupodece is admittedly pretty fun to say, though).

But first...

:warning: Steps to install crouton have changed! :warning:

Due to improved security within Chromium OS (yay!), the steps needed to launch the crouton installer, and the steps to run crouton from SD cards have to change a little.

Please read the relevant sections of this README carefully, and reach out to your favorite weblogger/tutorialer/videotuber to update their guides if they're behind the times. If you're successful, brag about your accomplishments in the issue tracker and earn the personal gratitude of the crouton authors*!

* limit one (1) gratitude per commenter

WHOA

Ok, back to business.

"crouton"...an acronym?

It stands for ChRomium Os Universal chrooT envirONment...or something like that. Do capitals really matter if caps-lock has been (mostly) banished, and the keycaps are all lower-case?

Moving on...

Who's this for?

Anyone who wants to run straight Linux on their Chromium OS device, and doesn't care about physical security. You're also better off having some knowledge of Linux tools and the command line in case things go funny, but it's not strictly necessary.

What's a chroot?

Like virtualization, chroots provide the guest OS with their own, segregated file system to run in, allowing applications to run in a different binary environment from the host OS. Unlike virtualization, you are not booting a second OS; instead, the guest OS is running using the Chromium OS system. The benefit to this is that there is zero speed penalty since everything is run natively, and you aren't wasting RAM to boot two OSes at the same time. The downside is that you must be running the correct chroot for your hardware, the software must be compatible with Chromium OS's kernel, and machine resources are inextricably tied between the host Chromium OS and the guest OS. What this means is that while the chroot cannot directly access files outside of its view, it_can_ access all of your hardware devices, including the entire contents of memory. A root exploit in your guest OS will essentially have unfettered access to the rest of Chromium OS.

...but hey, you can run TuxRacer!

What about dem crostinis though?

Crostiniis an official project within Chromium OS to bring the Linux shell and apps to the platform in verified mode with clean integration, multi-layered security, and all the polish you expect from Chromium OS proper.

That means compared to crouton, Crostini has official support, competent engineers, and code that looks a little less like ramen. crouton, in its defense, has wider device compatibility, enables direct hardware access, and is named after an objectively tastier bread-based food item.

There's a solid community on Reddit if you'd like to try Crostini out. If it works for you -- great! No hard feelings. If in the end you decide that crouton suits you better, read on!

Note: you can't get the best of both worlds by installing crouton inside of Crostini. The technology (and life itself) just doesn't work that way. Not to mention a crouton Crostini would look ridiculous and be impossible to eat without getting bits everywhere.

Prerequisites

You need a device running Chromium OS that has been switched to developer mode.

For instructions on how to do that, go to this Chromium OS wiki page, click on your device model and follow the steps in the _Entering Developer Mode_section.

Note that developer mode, in its default configuration, is completely insecure, so don't expect a password in your chroot to keep anyone from your data. crouton does support encrypting chroots, but the encryption is only as strong as the quality of your passphrase. Consider this your warning.

It's also highly recommended that you install the crouton extension, which, when combined with the

extension

or

xiwi

targets, provides much improved integration with Chromium OS.

That's it! Surprised?

Usage

crouton is a powerful tool, and there are a lot of features, but basic usage is as simple as possible by design.

If you're just here to use crouton, you can grab the latest release fromhttps://goo.gl/fd3zc. Download it, pop open a shell (Ctrl+Alt+T, type

shell

and hit enter), make the installer executable with

sudo install -Dt /usr/local/bin -m 755 ~/Downloads/crouton

, then launch it with

sudo crouton

to see the help text. See the "examples" section for some usage examples.

If you're modifying crouton, you'll probably want to clone or download the repo into a subdirectory of

/usr/local

and then either run

installer/main.sh

directly, or use

make

to build your very own

crouton

. You can also download the latest release, install it as above and run

crouton -x

to extract out the juicy scripts contained within, but you'll be missing build-time stuff like the Makefile. You also need to remember to place the unbundled scripts somewhere in

/usr/local

in order to be able to execute them.

crouton uses the concept of "targets" to decide what to install. While you will have apt-get in your chroot, some targets may need minor hacks to avoid issues when running in the chrooted environment. As such, if you expect to want something that is fulfilled by a target, install that target when you make the chroot and you'll have an easier time. Don't worry if you forget to include a target; you can always update the chroot later and add it. You can see the list of available targets by running

crouton -t help

.

Once you've set up your chroot, you can easily enter it using the newly-installed

enter-chroot

command, or one of the target-specific start* commands. Ta-da! That was easy.

Examples

The easy way (assuming you want an Ubuntu LTS with Xfce)

  1. Download
    crouton
  2. Open a shell (Ctrl+Alt+T, type
    shell
    and hit enter)
  3. Copy the installer to an executable location by running
    sudo install -Dt /usr/local/bin -m 755 ~/Downloads/crouton
  4. Now that it's executable, run the installer itself:
    sudo crouton -t xfce
  5. Wait patiently and answer the prompts like a good person.
  6. Done! You can jump straight to your Xfce session by running
    sudo enter-chroot startxfce4
    or, as a special shortcut,
    sudo startxfce4
  7. Cycle through Chromium OS and your running graphical chroots using Ctrl+Alt+Shift+Back and Ctrl+Alt+Shift+Forward.
  8. Exit the chroot by logging out of Xfce.

With encryption!

  1. Add the ```

-e

 parameter when you run crouton to create an encrypted chroot or encrypt a non-encrypted chroot.
2. You can get some extra protection on your chroot by storing the decryption key separately from the place the chroot is stored. Use the 

-k

 parameter to specify a file or directory to store the keys in (such as a USB drive or SD card) when you create the chroot. Beware that if you lose this file, your chroot will not be decryptable. That's kind of the point, of course.

### Hey now, Ubuntu 16.04 is pretty old; I'm young and hip

1. The 

-r

 parameter specifies which distro release you want to use.
2. Run 

crouton -r list

 to list the recognized releases and which distros they belong to.

### Wasteful redundancies are wasteful: one clipboard, one browser, one window

1. Install the [crouton extension](https://goo.gl/OVQOEt) into Chromium OS.
2. Add the 

extension

 or 

xiwi

 version to your chroot.
3. Try some copy-pasta, or uninstall all your web browsers from the chroot.

_Installing the extension and its target gives you synchronized clipboards, the option of using Chromium OS to handle URLs, and allows chroots to create graphical sessions as Chromium OS windows._

### I don't always use Linux, but when I do, I use CLI

1. You can save a chunk of space by ditching X and just installing command-line tools using 

-t core

 or 

-t cli-extra

2. Enter the chroot in as many crosh shells as you want simultaneously using 

sudo enter-chroot

3. Use the [Crosh Window](https://goo.gl/eczLT) extension to keep Chromium OS from eating standard keyboard shortcuts.
4. If you installed cli-extra, 

startcli

 will launch a new VT right into the chroot.

### A new version of crouton came out; my chroot is therefore obsolete and sad

1. Exit the chroot if you have it open.
2. If you haven't already, download 

crouton

, and copy it so it works: 

sudo install -Dt /usr/local/bin -m 755 ~/Downloads/crouton

3. Update your chroot with 

sudo crouton -u -n chrootname

. It will update all installed targets.

### I want to open my desktop in a window or a tab but I don't have the 'xiwi' target/xmethod.

1. Add 'xiwi' or any other target to an existing chroot with the 

-u

 option: 

sudo crouton -t xiwi -u -n chrootname


This will also make 'xiwi' the default xmethod.

1. If you want to keep the 'xorg' xmethod as the default then pick it first: 

sudo sh crouton -t xorg,xiwi -u -n chrootname


### 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. 

sudo edit-chroot -r chrootname

 restores the chroot from the most recent timestamped tarball. You can explicitly specify the tarball with 

-f

3. If your machine is new, powerwashed, or held upside-down and shaken, you can use the crouton installer to restore a chroot and relevant scripts: 

sudo crouton -f mybackup.tar.gz


_Unlike with Chromium OS, the data in your chroot isn't synced to the cloud._

### This chroot's name/location/password/existence sucks. How to fix?

1. Check out the 

edit-chroot

 command; it likely does what you need it to do.
2. If you set a Chromium OS root password, you can change it with 

sudo chromeos-setdevpasswd

3. You can change the password inside your chroot with 

passwd


### I want to install the chroot to another location

1. Use 

-p

 to specify the directory in which to install the chroot and scripts. Be sure to quote or escape spaces.
2. When entering the chroot for the first time each boot, you will first need to ensure the place you've installed the scripts is in a place that allows executables to run. Determine the mountpoint by running 

df --output=target /path/to/enter-chroot

, then mark the mount exec with 

sudo mount -o remount,exec /path/to/mountpoint

.
3. You can then launch the chroot by specifying the full path of any of the enter-chroot or start\* scripts (i.e. 

sudo /path/to/enter-chroot

), or use the 

-c

 parameter to explicitly specify the chroots directory.

_If for some reason you have to run the installer without touching the local disk, you can (for the time being) run

curl -fL https://goo.gl/fd3zc | sudo sh -s -- options_for_crouton_installer

. Note that this will definitely break in the near future, so don't depend on it._

### Downloading bootstrap files over and over again is a waste of time

1. Download 

crouton

2. Open a shell (Ctrl+Alt+T, type 

shell

 and hit enter)
3. Copy the installer to an executable location by running 

sudo install -Dt /usr/local/bin -m 755 ~/Downloads/crouton

4. Now that it's executable, use the installer to build a bootstrap tarball: 

sudo crouton -d -f ~/Downloads/mybootstrap.tar.bz2

5. Include the 

-r

 parameter if you want to specify for which release to prepare a bootstrap.
6. You can then create chroots using the tarball by running 

sudo crouton -f ~/Downloads/mybootstrap.tar.bz2

. Make sure you also specify the target environment with 

-t

.

_This is the quickest way to create multiple chroots at once, since you won't have to determine and download the bootstrap files every time._

### Targets are cool. Abusing them for fun and profit is even cooler

1. You can make your own target files (start by copying one of the existing ones) and then use them with any version of crouton via the 

-T

 parameter.

_This is great for automating common tasks when creating chroots._

### Help! I've created a monster that must be slain!

1. The delete-chroot command is your sword, shield, and only true friend. 

sudo delete-chroot evilchroot

2. It's actually just a shortcut to 

sudo edit-chroot -d evilchroot

, which I suppose makes it a bit of a deceptive Swiss Army knife friend...still good?

## Tips

- Chroots are cheap! Create multiple ones using 

-n

, break them, then make new, better ones!
- You can change the distro mirror from the default by using 

-m

- Want to use a proxy? 

-P

 lets you specify one (or disable it).
- A script is installed in your chroot called 

brightness

. You can assign this to keyboard shortcuts to adjust the brightness of the screen (e.g.

brightness up

) or keyboard (e.g. 

brightness k down

).
- Multiple monitors will work fine in the chroot, but you may have to switch to Chromium OS and back to enable them.
- You can make commands run in the background so that you can close the terminal. This is particularly useful for desktop environments: try running

sudo startxfce4 -b

- Want to disable Chromium OS's power management? Run 

croutonpowerd -i

- Only want power management disabled for the duration of a command?

croutonpowerd -i command and arguments

 will automatically stop inhibiting power management when the command exits.
- Have a Pixel or two or 4.352 million? 

-t touch

 improves touch support.
- Want to share some files and/or folders between ChromeOS and your chroot?  
Check out the 

/etc/crouton/shares

 file, or read all about it in the wiki.
- Want more tips? Check the [wiki](https://github.com/dnschneid/crouton/wiki).

## Issues?

Running another OS in a chroot is a pretty messy technique (although it's hidden behind very pretty scripts), and these scripts are relatively new, so problems are not surprising. Check the issue tracker and file a bug if your issue isn't there. When filing a new bug, include the output of

croutonversion

 run from inside the chroot or, if you cannot mount your chroot, include the output of 

cat /etc/lsb-release

 from Crosh.
## I want to be a Contributor!

That's great! But before your code can be merged, you'll need to have signed the [Individual Contributor License Agreement](https://cla.developers.google.com/clas/new?kind=KIND_INDIVIDUAL&domain=DOMAIN_GOOGLE). Don't worry, it only takes a minute and you'll definitely get to keep your firstborn, probably. If you've already signed it for contributing to Chromium or Chromium OS, you're already done.

If you don't know what to do with your time as an official Contributor, here's some suggestions:

- Really like a certain desktop environment? Fork crouton, add the target, and create a pull request.
- Feel like hacking around with Chromium OS integration? Fork crouton, improve integration, and create a pull request.
- Is your distro underrepresented? Want to contribute to the elusive and mythical beast known as "croagh"? Fork crouton, add the distro, and create a pull request.
- Discovered a bug lurking within the scripts, or a papercut that bothers you just enough to make you want to actually do something about it? You guessed it: fork crouton, fix everything, and create a pull request.
- Are most bugs too high-level for you to defeat? Grind up some[EXP](https://en.wikipedia.org/wiki/Experience_point) by using your fork to eat [pie](https://github.com/dnschneid/crouton/labels/pie).

## Are there other, non-Contributory ways I can help?

Yes!

## But how?

There's a way For Everyone to help!

- Something broken? File a bug! Bonus points if you try to fix it. It helps if you provide the output of 

croutonversion

 (or the output of

cat /etc/lsb-release

``` from Crosh) when you submit the bug.

  • Want to try and break something? Look through requests for testingand then do your best to brutally rip the author's work to shreds.
  • Look through open issuesand see if there's a topic or application you happen to have experience with. And then, preferably, share that experience with others.
  • Find issues that need wiki entriesand add the relevant info to the wiki. Or just add things to/improve things in the wiki in general, but do try to keep it relevant and organized.
  • Really like a certain desktop environment, but not up for coding? Open or comment on a bug with steps to get things working well.
  • Hang out in the #crouton IRC channel on freenode.net!

License

crouton (including this eloquently-written README) is copyright © 2016 The crouton Authors. All rights reserved. Use of the source code included here is governed by a BSD-style license that can be found in the LICENSE file in the source tree.

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