Tag Archives: chroot

CLI, OS

Rename LVM group in CentOS7

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I recently made the discovery that all my VMs have the same volume group name – the default that is given when CentOS is installed. My OCD got the best of me and I set out to change these names to reflect the hostname. The problem is if you rename the volume group containing the root partition, the system will not boot.

The solution is to run a series of commands to get things updated. Thanks to the centOS forums for the information. In my case I had already made the mistake of renaming the group and ending up with an unbootable system. This is what you have to do to get it working again:

Boot into a Linux rescue shell (from the installer DVD, for example) and activate the volume groups (if not activated by default)

vgchange -ay

Mount the root and boot volumes (replace VG_NAME with name of your volume group and BOOT_PARTITION with the device name of your boot partition, typically sda1)

mount /dev/VG_NAME/root /mnt
mount /dev/BOOT_PARTITION /mnt/boot

Mount necessary system devices into our chroot:

mount --bind /proc /mnt/proc
mount --bind /dev /mnt/dev
mount --bind /sys /mnt/sys

Chroot into our broken system:

chroot /mnt/ /bin/bash

Modify fstab and grub files to reflect new volume group name:

sed -i /etc/fstab -e 's/OLD_VG_NAME/NEW_VG_NAME/g'
sed -i /etc/default/grub -e 's/OLD_VG_NAME/NEW_VG_NAME/g'
sed -i /boot/grub2/grub.cfg -e 's/OLD_VG_NAME/NEW_VG_NAME/g'

Run dracut to modify boot images:

dracut -f

Remove your recovery boot CD and reboot into your newly fixed VM

exit
reboot

If you want to avoid having to boot into a recovery environment, do the following steps on the machine whose VG you want to rename:

Rename the volume group:

vgrename OLD_VG_NAME NEW_VG_VAME

Modify necessary boot files to reflect the new name:

sed -i /etc/fstab -e 's/OLD_VG_NAME/NEW_VG_NAME/g'
sed -i /etc/default/grub -e 's/OLD_VG_NAME/NEW_VG_NAME/g'
sed -i /boot/grub2/grub.cfg -e 
's/OLD_VG_NAME/NEW_VG_NAME/g'

Rebuild boot images:

dracut -f
Networking, OS

Use OpenVPN from within crouton chroot

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Update: Google released a ChromeOS update that broke the openvpn script. Find the updated version here.

Update 3/29/17: Added a DNS suffix line to fix broken DNS

I posted a little while ago about how to get openvpn working on your chromebook. That guide required that you run openvpn outside your chroot on the chromebook instance itself.

Lately I’ve been really feeling the need to have openvpn run within a crouton chroot instead. The solution is to take the script from the post above and divide it into two parts. One part you will still have to run outside your chroot but you will only have to do it once on each reboot. The other part can safely live inside your chroot.

First, on your chromebook itself (not in a chroot) make a small script to tell the shill service not to kill tun0:

sudo echo "
#!/bin/bash

#Allows the tun0 device to function
sudo stop shill
sudo start shill BLACKLISTED_DEVICES=tun0" > /usr/local/bin/shill

chmod +x /usr/local/bin/shill

Next, create this script within your chroot. Be sure to modify the environment variables to suit your setup.

#!/bin/bash

CONF_DIR="/path/to/directory/openvpn/config/is/in"
CONF_FILE="FILENAME_OF_OVPN_FILE"
NAMESERVER="IP_OF_DNS_SERVER_YOU_WANT_TO_USE"
SEARCH="DNS_SUFFIX_YOU_WANT_TO_USE"

cd "$CONF_DIR"

# Add google DNS on top of current ones, since openvpn command does not do it
sudo sed -i "1s/^/# new DNS\nsearch $SEARCH\nnameserver $NAMESERVER\n# old DNS\n/" /etc/resolv.conf

sudo openvpn --config "$CONF_FILE" --dev tun0

# When ctrl-c is hit remove tun0 and cleanup the DNS
sudo openvpn --rmtun --dev tun0
sudo sed -i '/# new DNS/,/# old DNS/d' /etc/resolv.conf
trap 2

Voila, we now have openvpn working inside our chroots again.

OS

Install Cinnamon on a Wily chromebook chroot

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I recently installed Ubuntu Wily Werewolf 15.10 as a chroot on my Chromebook Pixel 2. The process wasn’t as straightforward as I thought it would be so I will document it here.

First, I followed my own guide on how to set up a crouton chroot. The install would not complete – it was complaining about gnome-session-manager. I had to install the chroot with no GUI. This is the command I used (I specify a specific mirror to use because it’s much faster)

sudo sh ~/Downloads/crouton -r wily -t touch,extension,keyboard,cli-extra -e -n cinnamon -m http://mirrors.xmission.com/ubuntu

Once the initial chroot was set up, I installed cinnamon:

sudo apt-get install cinnamon-desktop-environment

After all that was installed, I followed my own guide on configuring cinnamon. I placed the following script in /usr/local/bin/startcinnamon on my chromebook (not the chroot)

APPLICATION="${0##*/}"

USAGE="$APPLICATION [options]

Wraps enter-chroot to start a Mint session.
By default, it will log into the primary user on the first chroot found.

Options are directly passed to enter-chroot; run enter-chroot to list them."

exec sh -e "`dirname "$0"`/enter-chroot" "$@" xinit

And I placed this file within the chroot, in my home directory:

echo "exec cinnamon-session" > ~/.xinitrc

I started by issuing the command

sudo startcinnamon

I noticed things didn’t look quite right. It turned out I was missing some icons.  Fix this by installing them:

sudo apt-get install gnome-icon-theme-full

I then discovered gnome-terminal wouldn’t run – it would simply crash on exit error 8. I discovered that it was due to missing locale settings. The fix was found here, which involves installing the gnome language pack and setting your locale.

sudo apt-get install language-pack-gnome-en
sudo update-locale LANG="en_US.UTF-8" LANGUAGE="en_US"

To instigate the changes you must exit all chroot instances.

That was it! After that bit of tweaking I have an Ubuntu 15.10 chroot working pretty well on my Chromebook Pixel 2.

 

CLI, Hardware, OS

Install Ubuntu chroot on your Chromebook

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I recently got a Chromebook Pixel 2015 LS. It is a very nice device. Chromium OS is great but a power user like myself wants a little more functionality out of this beautiful machine.

Fortunately it’s not too difficult to get an Ubuntu chroot running side by side with chromium. The Google developers have made a script to automate the process.

Below is my experience installing an Ubuntu Trusty chroot on my chromebook 2015 LS.

Prepwork

  • Enter developer mode:
    Press ESC, Refresh, power simultaneously (when the chromebook is on)

    • Every time you power on the chromebook from now on you’ll get a scary screen. Press CTRL-D to bypass it (or wait 30 seconds)
    • If you hit space on this screen instead of CTRL+D it will powerwash (nuke) your data
      A scary screen will pop up saying the OS is missing or damaged. Press CTRL D, then press Enter when the OS verification screen comes up.
  • Wait several minutes for developer mode to be installed. Note it will wipe your device to do this.

Install Crouton

Now that we’re in developer mode we will use a script called crouton to install an Ubuntu chroot (thanks to lifehacker for the guidance.)

  1. Download Crouton:  https://github.com/dnschneid/crouton
  2. Press CTRL ALT T to open terminal
  3. Type ‘shell’ (without quotes) and hit enter
  4. sudo sh ~/Downloads/crouton -r trusty -t touch,extension,unity-desktop,keyboard,cli-extra -e -n unity
    1. Note the arguments are suited to my needs. You will want to read up on the documentation to decide which options you want, i.e. desktop environment
  5. Install this crouton extension to integrate clipboard (in conjuction with the ‘extension’ parameter above)

General points of interest / lessons learned

  • Don’t enter the chroot and type startx. It will hard freeze your chromebook.
  • You don’t need to blow your chroot away if you want a different desktop environment, simply install desired environment on your existing chroot
  • To switch between chroots pres Ctrl + Alt + Shift + F2 or F3 (back or forward arrows on top row, not to be confused with the arrows on the bottom right of the keyboard)

High DPI

High DPI screens are a pain to deal with. Here are my tweaks:

  • Go to System settings / Displays / Scale for menu and title bars. I like 1.75
  • Alternatively you can change your resolution. If you mess up and X won’t start properly, delete ~/.config/monitors.xml (thanks to askubuntu)
  • Use the setres script to enable other resolutions in the display manager
    • setres 1440 960
  • Firefox fix tiny text:
    • go to about:config and modify layout.css.devPixelsPerPx, set to 2

Other tweaks:

  • Make trackpad match Chrome:
    • System settings / mouse and trackpad / Check “Natural Scrolling”
  • Remove lens suggestions:
    • Install unity-tweak-tool, notify-osd, overlay-scrollbar, unity-webapps-service
    • Run unity-tweak-tool and uncheck “search online sources” from the search tab
  • Move docky bar to the left:
    • sudo apt-get install gconf-editor
    • Press Alt+F2, enter: gconf-editor and in this configuration editor, navigate to “apps -> docky-2 -> Docky -> Interface -> DockPreferences -> Dock1″
    • On the right side there are some properties with their corresponding values, including the position of the dock which you can change from “Bottom” to “Top/Left/Right” to move Docky to the upper part of the desktop.
  • Install Mac OSX theme
  • Install elementary OS chroot

Garbled mouse cursor when switching between chroots

Sometimes the mouse cursor would get all weird when switching between my chroots. The fix is to install the latest Intel drivers within your chroot.

sudo apt-get install software-properties-common python-software-properties
sudo add-apt-repository https://download.01.org/gfx/ubuntu/14.04/main
wget --no-check-certificate https://download.01.org/gfx/RPM-GPG-KEY-ilg -O - | sudo apt-key add -
wget --no-check-certificate https://download.01.org/gfx/RPM-GPG-KEY-ilg-2 -O - | sudo apt-key add -
sudo apt-get update
sudo apt-get upgrade

That’s it.. for now 🙂

 

Update 07/27/2015

I discovered that creating chroots was taking a very long time due to the mirror being chosen. I discovered the -m parameter of crouton which allows you to specify a mirror of your choosing. My updated setting is thus:

sudo sh ~/Downloads/crouton -r trusty -t touch,extension,kde-desktop,keyboard,cli-extra -e -n unitykde -m http://mirrors.xmission.com/ubuntu

If you happened to do a CTRL + C to cancel an existing chroot install that was going slowly, you can simply append the -m parameter above along with -u -u to resume with the updated mirror:

sudo sh ~/Downloads/crouton -r trusty -t touch,extension,kde-desktop,keyboard,cli-extra -e -n unitykde -m http://mirrors.xmission.com/ubuntu -u -u