How to root Nexus S using Ubuntu

Configure udev to recognize fastboot device.

vi /etc/udev/rules.d/51-android.rules

SUBSYSTEMS=="usb", SYSFS{idVendor}=="18d1", MODE="0666"
SUBSYSTEMS=="usb", SYSFS{idVendor}=="0bb4", MODE="0666"
SUBSYSTEMS=="usb", SYSFS{idVendor}=="22b8", MODE="0666"

In this case, Nexus vendor id is "18d1"
See
http://developer.android.com/guide/developing/device.html
for all the vendor ids available.

sudo /etc/init.d/udev restart

sudo reload udev


sudo adb reboot bootloader

choose unlock bootloader


You must have Built Android source code to use fastboot command

cd /jian/mydroid/out/host/linux-x86/bin/
fastboot oem unlock

Now back on this screen you should read
LOCK STATE - UNLOCKED

Download the ClockworkMod recovery image,
fastboot flash recovery recovery.img

Download su-2.3.6.1-ef-signed.zip
adb push su-2.3.6.1-ef-signed.zip /sdcard/su-2.3.6.1-ef-signed.zip
adb reboot bootloader

Select "Recovery

Select "Install ZIP from sdcard" (power button to apply)

Select "Choose ZIP from sdcard" (power button to apply)

Select su-2.3.6.1-ef-signed.zip (power button to apply)

Select "Yes - su-2.3.6.1-ef-signed.zip"


and then reboot, now you should can use
adb shell
su

to get root permission.

Reference:
http://forum.xda-developers.com/showthread.php?t=1007782