Currently I am working in a software company as a Test engineer. I am assigned to automate our manual testing process in an application, both in Windows and Unix (Linux and Sun Solaris). We have license for all IBM Rational products. The application is written by Java. As an automation expert, can you please advice on a proper tool for this automation? The application installation process on both Windows and Linux is almost same. So can we use the same code (that we use in Windows) for Linux as well? If can, what would be the way? If not, what would be the exact Rational automation tool for UNIX platforms?

Or are there any open source automated tool which i can use for all UNIX flavor ?