hi i am using ubuntu 12.04. and in ~/.bashrc file I set following things
export ANDROID_HOME=/home/nilkash/Downloads/android-sdk-linux/platform-tools
if the problem still exist please make sure that you have the right permissions try sudo chmod -R 777 /home/your-user-name/.cordova/
Also make sure that you are NOT using sudo to add Android as a platform
This is incorrect in the default Cordova installation
sudo cordova platform add android
Just do cordova platform add android