Android emulator gives "SDL init failure" error on Ubuntu/Linux

If you are getting the following error:

SDL init failure, reason is: No available video device

from Android emulator on a Unix/Linux platform, this typically indicates your shell's DISPLAY variable is not pointing to the correct X11 Display. Try launching the Android emulator as shown below. You may add your own parameters as needed as long the DISPLAY=:0 is there.

DISPLAY=:0 emulator -kernel your_zImage -system your_system.img -ramdisk your_ramdisk.img -sdcard your_sdcard.img