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Linux HOWTO

Unlock and Root Your Nexus Using Linux

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Introduction

I’ve had a lot of trouble gathering information on how to unlock and root my Nexus 6 phone (having never done anything like this before). The information on how to do this is definitely out there, but it’s all over the place in bits and pieces. So that’s where this blog comes in; I tried to group everything I learned after successfully rooting my phone and installing TWRP on it.

This diagram explains very loosely how the upgrades work; the diagram will make more sense as you read on.
Nexus Upgrade In Nutshell
Here are the topics of interest:

  • Installing the Android SDK and preparing a useful (Linux) Environment: This step is important in order to be able to interact with your device and update it via a USB cable attached to your PC. It specifically focuses on enabling the use of the adb and fastboot tools. This entire blog is useless to you if you don’t have this part set up.
  • Enabling Debug (Developer) Mode on your Android device: This step pairs with the SDK. The SDK allows your PC to communicate with your Android device while this step allows your device to be communicated with. Each device you plan on unlocking or rooting will have to have Debug Mode turned on.
  • Unlock Your Bootloader: You can not root your device unless your bootloader is unlocked. This action opens your device up to a world of tweaks and hacks. Note: this step can also can void your warranty.
  • Root Your Device: You can not root your device unless your bootloader is unlocked. This step focuses on using the excellent work of Chainfire‘s (CF-)Auto-Root boot.img and SuperSU application.
  • Upgrade Your Rooted Device: When Google puts out their new Over The Air (OTA) upgrade. You’ll notice that rooted devices won’t successfully get upgraded. Don’t worry; nothing breaks, the update simply fails. I identify the steps here how you can play along and still upgrade your rooted device.

A few other things worth sharing:

  • Fantastic Android (Root Required) Apps: Got your Android device rooted? Here are some amazing applications worth installing on it.
  • TWRP Setup: TWRP allows you to try out custom firmware. This is one of the fantastic apps i had to make a separate section for since it’s setup can be a bit confusing if you’ve never done it before.
  • Backups and Restores: Just some tips I found on creating backups and their accompanied restoring operations (in a time of need).

Getting Started

I performed all of the steps below on a Fedora 20 Linux box, but it should work on any variation of Linux (the instructions that is). Please note that these steps are specifically geared towards a Nexus 6, but I’m sure any competent person can adjust what is identified here to work with their own Android device (phone/tablet) too. 🙂

Android SDK Preparation

This step is vital for the two-way communication to your device using your PC. I did the following using Fedora 20; but the rules don’t change for most distributions.

  1. As root, make sure the proper libraries are installed and available to your environment: 
    # You'll need the 32-bit version of libstdc and the JDK 
yum install libstdc++.i686 java-1.7.0-openjdk -y
  2. Download the full Android SDK here (scroll to the bottom of the page>DOWNLOAD FOR OTHER PLATFORMS>SDK Tools Only). At the time I did this, the file was called: android-sdk_r24.0.2-linux.tgz. 
    # Alternatively, you can fetch it this way
# (as long as the site doesn't change their paths around):
wget http://dl.google.com/android/android-sdk_r24.0.2-linux.tgz
  3. Install it’s contents into a workable directory; the following prepared my development environment placing everything in ”’~/Development/Android/SDK”’: 
    mkdir -p ~/Development/Android/SDK
# Extract contents of the SDK into our newly created directory
# the --strip 1 eliminates the parent directory (called android-sdk-linux)
# we just want the root of this to go into the SDK directory instead
tar xvfz android-sdk_r24.0.2-linux.tgz -C ~/Development/Android/SDK --strip 1
  4. The following will allow regular users to utilize the fastboot command. Without this step, you must switch to root to utilize the command.

    cat < /etc/udev/rules.d/51-android.rules
# Nexus 6 ID: 18d1
SUBSYSTEM=="usb", ATTR{idVendor}=="18d1", MODE="0666", GROUP="plugdev" 
_EOF
chmod 644 /etc/udev/rules.d/51-android.rules
  5. Now we need to add a few more tools to complete our setup. This can be done through the tools/android binary.

    # Create an environment variable to simplify the commands
ASDK="$HOME/Development/Android/SDK"
# Change to our development directory
pushd $ASDK
# Update our path
export PATH="$PATH$ASDK/tools:$ASDK/platform-tools"

# Install (the following were in the SDK r24.0.2 package)
# they may be different in yours.
#  1- Android SDK Platform-tools
#  2- Android SDK Build-tools
# 57- Android Support Library
#
# The following command lists all of the packages you can install:
#    > android list sdk
#
# If you want to be certain you grab the right packages and
# are using a different release, here is a cheat that will
# fetch this information for you:
PACKAGES=$(tools/android list sdk --extended | 
            egrep -B2 -i 'Android (Support Library|SDK Platform-tools|SDK Build-tools)' | 
            egrep '^id:' | 
            sed -e 's/[^"]+"([^"]+)"/1/g' | 
            cut -d- -f1 | tr -s '[:space:]' , | 
            sed -e 's/,+$//g')

# Now install our packages! (if there are any to install)
android update sdk -u -a -t $PACKAGES

# if you get the following error, it's because you didn't install
# libstdc++ as identified in an earlier setup:
#   ...
#   Stopping ADB server failed (code 127).
#   Starting ADB server failed (code 127).
#   Done. 3 packages installed.
#
# To fix this, make sure you have installed the 32-bit libstd++ (as root):
#    yum install libstdc++.i686
#
# After it's installed, you can restart the adb server with the
# following command:
#     adb start-server

    Alternatively, you can just launch the tools/android binary and use the GUI to set things up. You will need to install the following (3) packages (minimally):

    1. Tools >> Android SDK Tools
    2. Tools >> Android SDK Platform-tools
    3. Extras >> Android Support Library
  6. You can test to see if you’ve got everything working by preforming the following: 
    # Tests if the adb-server is successfully running
adb version

# NOTE:
# If it doesn't work, don't panic (yet); try killing the server
# (it's possible it's not even running) and restarting it:
adb kill-server
adb start-server
  7. Now try testing the command identified earlier again: 
    adb version

    If it displays Android Debug Bridge version x.x.x, then you’ve completed the first part successfully.

Enable Development / Debugging Mode on Device

You must log into your device and access the settings to enable Development / Debugging mode:

  1. Go into Settings.
  2. Under About, you’ll be able to locate your Build Number.
  3. Tap Build Number 7 times until you are notified that you have activated Developer options.
  4. Go into Developer Options, ensure it is enabled and check the Enable OEM Unlock checkbox.
  5. While in Developer Options, ensure the USB Debugging checkbox is checked too.

Unlock the Bootloader

Once the bootloader is unlocked, your Android device will prompt you that it will erase everything.
Before proceeding with this step, make sure you’ve backed up everything important to you. Preferably you’re doing this step with a brand new device so you have nothing to lose at this time.

  1. Turn the device off (if it’s on already) and turn it back on while holding the volume down and the power button at the same time. This will start your device into the bootloader/fastboot mode.
  2. Plug the device into your PC (via a USB cable), then open a command prompt window window and type the following: 
    # Create an environment variable to simplify the commands
ASDK="$HOME/Development/Android/SDK"
# Change to our development directory
pushd $ASDK
# Update our path
export PATH="$PATH:$ASDK/tools:$ASDK/platform-tools"

# list the devices detected in fastboot mode:
fastboot devices

    If your device’s serial number shows up, you are good to go! If not, you’ll need to figure this part out before continuing.

  3. This next step will completely wipe EVERYTHING off of your device. Make sure to back up anything worth saving before proceeding. If you’re having second thoughts about this; now is the time to back out. You can reboot your device again and it will return how it was.

    Otherwise, for all intent and purposes, unlock the bootloader with the following command:

    fastboot oem unlock

    On the device (still attached to the computer), a screen should pop up asking whether or not you would like to unlock the bootloader. Use the volume rockers to highlight “Yes” then press power to confirm the action.
    After the above command has finished executing, run the following to restart your device:

    fastboot reboot

    The device will reboot at this time.

    Next you will be presented with a screen containing an Android logo as well as a progress bar. It can take about 8 minutes or so to finish.

    When it’s complete, it will restart and act as though it was the first time you’ve ever turned on the device. There is no sense in doing anything yet, we still have a few more steps to do. Just power off the device at this time and keep reading.

Root Your Android Device

Your bootloader must be unlocked for this step to work correctly. Otherwise, you can root your device with the following actions:

  1. Download the Chainfire‘s (CF-)Auto-Root tool to automate everything for you downloadable from here.
  2. Extract the ZIP file to your Desktop; this makes it easy to access.
  3. Turn the device off (if it’s on already) and turn it back on while holding the volume down + power button at the same time. This will start your device into the bootloader/fastboot mode.
  4. Plug the device into your PC (via a USB cable), then open a command prompt window window and type the following: 
    # Create an environment variable to simplify the commands
ASDK="$HOME/Development/Android/SDK"
# Change to our development directory
pushd $ASDK
# Update our path
export PATH="$PATH:$ASDK/tools:$ASDK/platform-tools"

# Create a directory to place the Auto-Root contents in:
mkdir -p "$ASDK/autoroot"

# Uncompress contents to this directory:
unzip CF-Auto-Root-shamu-shamu-nexus6.zip -d "$ASDK/autoroot"

# Reboot your device into bootloader mode (power+volume down or this option):
adb reboot bootloader

# Now root your device with the following commands:
IMAGE=$(find autoroot/image -type f -name '*.img')
chmod ug+x autoroot/tools/fastboot-linux
autoroot/tools/fastboot-linux boot "$IMAGE"

Upgrade Your Rooted Device

When Android v5.1 came out; the OTA failed (rebooted to an ‘error’). I had to fetch the stock version I was currently running so I could specifically just flash 2 images (system and recovery).

  1. Setup your development environment 
    # Create an environment variable to simplify the commands
ASDK="$HOME/Development/Android/SDK"
# Change to our development directory
pushd $ASDK
# Update our path
export PATH="$PATH:$ASDK/tools:$ASDK/platform-tools"
  2. The point of this section is you want to update your Android ‘without’ losing your data.Nexus 6 Settings Build Number

    Download the stock firmware associated with the (rooted) version currently installed on your device here. The steps below will show you how you can access what is important from what you just downloaded.

    The best way to be sure you’re downloading the correct version is to go into the About settings of your device and pay attention to Build number identified at the bottom. You just need to download and work with this version as your base.

    # 5.0.1 shamu Stock (Nexus 6); You will need to visit the following
# website to get the right firmware for your device if it's not the
# same version I'm using: 
# - https://developers.google.com/android/nexus/images
#
wget https://dl.google.com/dl/android/aosp/shamu-lrx22c-factory-ff173fc6.tgz
mkdir -p "$ASDK/firmware.nexus.6-shamu.5.0.1"
tar xvfz shamu-lrx22c-factory-ff173fc6.tgz -C "$ASDK/firmware.nexus.6-shamu.5.0.1"  --strip 1

# Change into our Firmware Directory
pushd "$ASDK/firmware.nexus.6-shamu.5.0.1"

######################################
# After previously running the update from 5.0.1 to 5.1.0
# My Nexus was updated to LMY47D (seen from options)
# So this can be set up as follows:
wget https://dl.google.com/dl/android/aosp/shamu-lmy47d-factory-6c44d402.tgz
mkdir -p "$ASDK/firmware.nexus.6-shamu.5.1.0"
tar xvfz shamu-lmy47d-factory-6c44d402.tgz -C "$ASDK/firmware.nexus.6-shamu.5.1.0"  --strip 1

# Change into our Firmware Directory
pushd "$ASDK/firmware.nexus.6-shamu.5.1.0"

######################################
# After the update from 5.1.0 to 5.1.1 was successful
# I checked for the version i was running for a recovery
# point (in the future)
# My Nexus was updated to LMY47Z (seen from options)
# So this can be set up as follows:
wget https://dl.google.com/dl/android/aosp/shamu-lmy47z-factory-33951732.tgz
mkdir -p "$ASDK/firmware.nexus.6-shamu.5.1.1"
tar xvfz shamu-lmy47z-factory-33951732.tgz -C "$ASDK/firmware.nexus.6-shamu.5.1.1"  --strip 1

# Change into our Firmware Directory
pushd "$ASDK/firmware.nexus.6-shamu.5.1.1"

######################################
# The below applies to any firmware previously downloaded above

# Extract the system images next
unzip *.zip -d image

# Reboot your device into bootloader mode (power+volume down or this option):
adb reboot bootloader

# Flash the 2 critical images that will allow your OTA to properly
# update itself. You will loose 'root' if you've done so.
# Don't worry; you won't lose your data when you do this.
fastboot flash system image/system.img
fastboot flash recovery image/recovery.img

# If you've got other boot modifications (mods) installed (such as TWRP
# or BusyBox) running your Android device in an unencrypted mode,
# you should additionally run the following:
fastboot flash boot image/boot.img

# If you have nothing to lose and just want to completely reset
# your device to the version you downloaded, you can run the command:
#    ./flash-all.sh
# Otherwise, don't do this (to save your data)!! Just move on
# to the next command identified below to reboot.

# Your device no longer has root access at this point
# you can reboot it now
fastboot reboot

popd
  3. Nexus 6 OTA UpdateAfter the reboot, you will have lost your root privileges. However, you can now upgrade using the OTA update Google provides. Once the OTA upgrade has complete, you can re-root your device using the steps already identified above.

Fantastic (Root Requiring) Apps to Install

Here are some great apps worth installing on your rooted devic:

If you’re feeling brave and want to start playing with custom firmware:

If I forgot one, or you have one to share; please feel free to let me know and I’ll add it!

TWRP Setup

TWRP allows you to backup your firmware as well as flash and install/uninstall custom firmware. It requires (Stericson) BusyBox or BusyBox Pro to work correctly. Naturally it also requires that your device is rooted already. Here are the devices TWRP support. For the Nexus 6; here is the direct link.

You can think of this application has installing 2 key components onto your device:

  • The .apk (front end application) which provides you with some rudimentary control to it’s backend. This is a simple app you just download from the Google Play store here.

    It provides you with the ability to flash the backend for you. I’ll explain how to flash it manually below; the only advantage of doing it manually is you can use some of the newer firmware that hasn’t made it back to the .apk yet. That and you know for certain you’ll flash the right ROM as using the .apk gives you the ‘chance’ to brick your device through accidental choice selections.

  • The backend itself. This is the beauty behind TWRP. It’s an image file you need to flash directly to your device (overwrite the stock version). Through this you can:
    1. Backup your entire device’s state (everything; including the firmware you’re running)
    2. Restore any previous backup you already created.
    3. Flash a new custom firmware you feel is worth trying without worry for if something goes wrong, you can just restore a backup. Note: It’s presumed that the first thing you do once you get this software installed is backup your current system so you have a good restore point.
  1. Setup your development environment 
    # Create an environment variable to simplify the commands
ASDK="$HOME/Development/Android/SDK"
# Change to our development directory
pushd $ASDK
# Update our path
export PATH="$PATH:$ASDK/tools:$ASDK/platform-tools"
  2. The point of this section is you want to update your Android ‘without’ losing your data.

    Download the stock firmware associated with the (rooted) version currently installed on your device here and prepare it’s content. If you have nothing to loose; the easiest way is to just flash everything using the latest stock firmware. But if you’re like me; here is the custom steps i took to upgrade from 5.0.1 to 5.1.0.

    # 2.8.6.0 shamu Stock (Nexus 6); You will need to visit the following
# website to get the right firmware for your device if it's not the
# same version I'm using:
# - http://dl.twrp.me/shamu/

[ ! -d "$ASDK/twrp/" ] && mkdir -p "$ASDK/twrp/"
pushd "$ASDK/twrp/"
# At the time; the latest image was twrp-2.8.6.0-shamu.img
curl --referer http://dl.twrp.me/shamu/twrp-2.8.6.0-shamu.img 
     -O http://dl.twrp.me/shamu/twrp-2.8.6.0-shamu.img

# Reboot your device into bootloader mode (power+volume down or this option):
adb reboot bootloader

# Flash the recovery image with TWRP's version
fastboot flash recovery twrp-2.8.6.0-shamu.img

# You now have TWRP installed
fastboot reboot

popd

Backup / Restore

  • TWRP allows you to preform full backups and restores of your device without the need of a PC connected to it. It doesn’t hurt to use this option. In order to do this; it needs to modify the recovery ROM of your device. But this isn’t really a big deal since you can easily flash it back to where it was using the firmware provided on Google’s website. Note: This application requires that your device is already rooted.
  • Titanimum Backup allows you to backup your applications and even clean out the ones you don’t want. This application is an absolutely MUST for all rooted devices!
  • Android SDK supports backups and restores too.Here is a great forum post explaining the whole operation in great detail; but in short the following commands will do the trick (assuming your device is powered on). 
    # Create an environment variable to simplify the commands
ASDK="$HOME/Development/Android/SDK"
# Update our path
export PATH="$PATH:$ASDK/tools:$ASDK/platform-tools"

# Create Backup
adb backup -f $(date +'%Y.%m.%d-nexus6.backup') -apk -shared -all

# You can later restore this file with the command:
adb restore YYYY.MM.DD-nexus6.backup

    The nice thing about the built in Android backup and restore commands is that they don’t require a rooted device to use. Your device has to be unlocked and connected to your PC (via USB) for this option to work though! Honestly, if your device is already rooted, then TWRP and Titanium Backup are the best solutions.

Reverting Everything Back

Sometimes you may want to revert everything back to how it was. This is especially an essential step if you have to send your device back to Google (or another carrier) to full fill it’s warranty.

  1. Setup your development environment 
    # Create an environment variable to simplify the commands
ASDK="$HOME/Development/Android/SDK"
# Change to our development directory
pushd $ASDK
# Update our path
export PATH="$PATH:$ASDK/tools:$ASDK/platform-tools"
  2. Download the stock firmware associated with your device here and prepare it’s content.

    # 5.0.1 shamu Stock (Nexus 6); You will need to visit the following
# website to get the right firmware for your device if it's not the
# same version I'm using: 
# - https://developers.google.com/android/nexus/images
# 2015 Jan - Updated Nexus 6 to v5.1.0; Future flashes for myself
#            will involve treating that version as my stock instead.
wget https://dl.google.com/dl/android/aosp/shamu-lrx22c-factory-ff173fc6.tgz
mkdir -p "$ASDK/firmware.nexus.6-shamu.5.0.1"
tar xvfz shamu-lrx22c-factory-ff173fc6.tgz -C "$ASDK/firmware.nexus.6-shamu.5.0.1"  --strip 1

# now run the firmware restore
pushd "$ASDK/firmware.nexus.6-shamu.5.0.1"
# This command does it all and restarts the device when your done.
./flash-all.sh
popd
  3. Now you need to re-lock the device. The easiest way to do this is power on the device with the power and volume down button held down.

    Note: if you are in a unique position where the volume down button doesn’t work (making it impossible to do the bootloader combination; do the following:

    • Log back into your device using any user (it really doesn’t matter); Don’t bother putting your real information in otherwise you’ll have to wait while your device downloads and re-installs all of your apps. The main thing is you need to enable the developer mode again and Debugging Mode. You will be prompted to authorize the connection within your device (make sure to do so).
    • Once Debugging Mode is enabled, you can connect your device up to your laptop and type the following: 
      adb reboot bootloader
    • You can safely relock your device with the following command: 
      fastboot oem lock

      After the above command has finished executing, run the following to restart your device:

      fastboot reboot

      The device will reboot at this time.

    Next you will be presented with a screen containing an Android logo as well as a progress bar. It can take about 8 minutes or so to finish.

    When it’s complete, it will restart and act as though it was the first time you’ve ever turned on the device. You can safely power it off now. It’s good to be shipped back to Google!

Sources

Credit

This blog took me a very long time to put together and test! If you like what you see and wish to copy and paste this HOWTO, please reference back to this blog post at the very least. It’s really all I ask.