Want to gain root access on your Galaxy Nexus. Here is a quick guide to help your root your Ice Cream Sandwich smartphone using ADB aka Android Debug Bridge. As ADB is available for all major platforms like Windows, Mac and Linux, Rooting Galaxy Nexus is possible on any PC running any of these three platforms.
If you don’t already have ADB on your mac or Windows PC, then check out the tutorial for Windows Here and for Mac here.
After you have setup ADB, you will need to download two files to complete the process.
STEP 1: Extract both the RAR files that you have just downloaded.
STEP 2: Copy the required Fastboot file depending on your platform to ADB folders. For Ex: If you are using Windows, copy fastboot-windows.exe to ADB folder. Same in the case of mac and linux.
STEP 3: Turn on USB Debugging on your Galaxy Nexus.
STEP 4: Install Driver from the Galaxy Nexus Manual Root folder. File name is Samsung_USB_Driver_for_Moblie_Phones_v1_4_6_0.exe
STEP 4: Connect Galaxy Nexus to your computer via the microUSB cable and check if ADB is working properly by running adb devices in the terminal or command line. If it shows Galaxy Nexus, then you are good to go to next steps, else properly install ADB.
STEP 4: Turn off your Galaxy Nexus
STEP 5: Turn on your Galaxy Nexus in Bootloader mode [How to do that – Press 'volume up' and 'volume down' and ‘power button’ at the same time] [See the image below]
STEP 6: Run the following commands in Windows.
fastboot-windows oem unlock
For MAC and Linux use the following commands
fastboot-linux oem unlock
fastboot-mac oem unlock
STEP 7: Press Yes on your phone once it asks your confirmation to unlock the bootloader.
STEP 8: Run the following command
fastboot boot boot.img
STEP 9: Your Galaxy Nexus will now reboot. Make sure to enable Debugging.
STEP 10: Run the following command, one by one and make sure to keep the right path to the files being pushed.
adb push su /system/bin
adb push Superuser.apk /system/app
adb shell chmod 06755 /system/bin/su
adb shell chmod 06755 /system/app/Superuser.apk
STEP 11: Your Galaxy Nexus is rooted, enjoy
In case of any issues, consult the original forum thread over here.