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Customize ChromeOS Crosh Terminal with Custom Fonts and Solarized Dark Theme

Customize Chromebook Chrosh Shell Environment

Requirement: Chromebook, Common Sense, Commandline Ablity, 1 hour of time

Dear developers with a spare Chromebook lets inject a little personalization into your Crosh shell with custom fonts, the solarized theme, and extra secure shell options.

Also, keep in mind that the terms Chrosh, Chrosh Window, and Secure Shell all refer to various versions and extentions built around the ChromeOS terminal. Settings that affect the ChromeOS terminal are global.

Custom Fonts

If ChromeOS was a normal Linux distribution, adding fonts would be as easy as dropping a font file into the .fonts folder and changing a terminal setting. Sadly, we need to do a bit of work - some of it rather scary - to get custom fonts working with ChromeOS.

Mounting Root Filesystem as Read-Write

Chromebook must be in developer mode and have rootfs verification turned off so that the root read only file system can be remounted as read-write. Once this is done, extra fonts can be added to ChromeOS's font folder.

WARNING: Follow instructions very carefully. Failure to follow these instructions can result in a non-booting Chromebook. If you screw up you will need to restore your Chromebook to stock. You have been warned.

  1. Fire up the Crosh shell with ctrl+alt+t

  2. sudo /usr/share/vboot/bin/make_dev_ssd.sh --remove_rootfs_verification

  3. The above command will fail and tell you to run with --partitions N flag at the end where N can be any number. Run the command again with the new flag.

  4. sudo crossystem dev_boot_signed_only=0

  5. The above command turns the verification check off. Because of step 2, the Chromebook will fail to boot if the verificaiton check is on.

  6. sudo mount -o remount,rw /

  7. Reboot your Chromebook. The root file system is now mounted as read-write.

Congrats. The dangerous part of the setup is done.

Font Folder Location and Font Install

Fonts in .ttf format can be installed to the folder /usr/share/fonts/croscore/

Installing either the normal or powerline patched versions of your favorite monospaced fonts to the aforementioned folder is required for proper configuration of the font family settings in Secure Shell a bit latter.

https://github.com/Lokaltog/powerline-fonts

I prefer the powerline patched version of Ubuntu Mono. Other mono space fonts - including Adobe's Source Code Pro - are great fonts for Crosh usage too!

Add Required Chrome Extentions

To further customize our Crosh window, install both Secure Shell and the Crosh Window extentions from the Chrome Web Store.

Sett Up Chrosh's Font-Family and Font-Size

ChromeOS apps menu > right click on the Secure Shell icon > select options

Change the terminal settings as you see fit. Pay special attention to:

font-family

Keep in mind ChromeOS will only load the first avaliable font that you specified in the font-family field. If you wan to use a custom font make sure you added it as the first entry. For example, if using Ubuntu Mono add "Ubuntu Mono", in front of the current font stack to properly add Ubuntu Mono

font-size

Since Ubuntu Mono is slighly smaller than the default font, you may want to bump the size up from 15 to a modestly larger 16 or 17.

Solarized Color Theme

It's almost criminal how easy it is to install solarized for Crosh.

I'm including the code for the prefs.js file I used for convenience.

// Disable bold 
term_.prefs_.set('enable-bold', false) 

// Use this for Solarized Dark 
term_.prefs_.set('background-color', "#002b36");
term_.prefs_.set('foreground-color', "#839496");

// Solarized Colors
term_.prefs_.set('color-palette-overrides', [
  '#073642', 
  '#dc322f', 
  '#859900', 
  '#b58900', 
  '#268bd2', 
  '#d33682', 
  '#2aa198', 
  '#eee8d5', 
  '#002b36', 
  '#cb4b16', 
  '#586e75', 
  '#657b83', 
  '#839496', 
  '#6c71c4', 
  '#93a1a1', 
  '#fdf6e3'
]);
  • Open the Chrome Javascript Console ctrl+shift+j
  • Paste the contents of your solarized prefs.js file into the console
  • Hit enter

Further Customizations

Loading a Crosh Window based Ubuntu 14.04 Chroot is the best way to make use of the customizations.

For powerline patched font use in vim:

  • add bling/vim-airline to vim
  • edit your .vimrc to include let g:airline_powerline_fonts = 1

For powerline patched font use in tmux:

  • Install ZSH shell, oh-my-zsh, and set the zsh-theme to agnoster

Fin

Thanks for reading!

@sharktamer

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sharktamer commented Mar 15, 2015

Thanks for the post, the font installation stuff is gonna be very handy.

Do you have a nice way of having crosh enter the chroot automatically when you open it?

@cwegener

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cwegener commented Aug 8, 2015

Here's a better way to install PowerLine fonts in ChromeOS without modifying the root partition
https://github.com/wenlock/myhome/blob/master/opt/docs/powerline-fonts.md

@colemickens

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colemickens commented Jan 31, 2016

You can skip a lot of this (including all of the rootfs disabling) by choosing a different location for the font storage. I've placed my fonts in /var/fonts and everything works as expected after a reboot. (Note, you'll have to change .fonts.conf accordingly).

@brandontaylor1994

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brandontaylor1994 commented May 6, 2016

I'm getting the following error after running the last "dangerous" command. What am I missing?

chronos@localhost / $ sudo mount -o remount,rw /
mount: cannot remount /dev/dm-0 read-write, is write-protected

@arturodr

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arturodr commented May 8, 2016

you have to reboot after
sudo crossystem dev_boot_signed_only=0

@brandontaylor1994

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brandontaylor1994 commented May 16, 2016

Thank you. I eventually figured that one out. The steps just said not to restart until after so I was nervous.

On a different note, I'm now trying to get powerline fonts working in my chroot session (precise). When I type fc-list, "PowerlineSymbols:style=Medium" is included in the list but I still have missing characters at the beginning and end of my current path. Any help with this would be appreciated.

Thanks

@forresthopkinsa

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forresthopkinsa commented Jul 8, 2016

Agreed, this is a safer method of adding fonts, and it works

@rosshinkley

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rosshinkley commented Jul 16, 2016

Is there a way to apply prefs.js from the command line itself? It'd be really nice to be able to apply different color schemes without having to copy/paste the preferences into the dev console every time.

@trusktr

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trusktr commented May 17, 2017

How do we reverse all the stuff we did in Mounting Root Filesystem as Read-Write?

@mfergu

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mfergu commented Oct 31, 2017

I'm following the instructions for Solarized Color Theme and it is not working.

@Noisytoot

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Noisytoot commented Apr 12, 2018

It is spelt crosh not chrosh

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