Just a little update. I am now able to build the Workbench in Ubuntu Linux but I still get error building the client package.
I now googling the error "an error occur while listing Android target" --> this could be
1.) not finding the sdk but the path is working since I have tested it and can build cordova apps from the commandline.
2.) A particular sdk target is missing --> I have updated and installed sdk 19 (all 4.4.2 components including the build tools) but I will install all
other sdk packages from the latest to the oldest. It will eat my hard space but I need to get to the root of the error here

Many thanks!
God blesses!!!
Best regards,
Sanyaade