Rosetta Stone is not available for Linux but there are a few alternatives that runs on Linux with similar functionality. The best Linux alternative is Learning with Texts, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 100 alternatives to Rosetta Stone and four of them are available for Linux so hopefully you can find a suitable replacement. Other interesting Linux alternatives to Rosetta Stone are Influent (Paid), Live Lingua (Paid, Open Source) and WordListHub.com (Free, Open Source).
Learning with Texts (LWT) is a free tool for Language Learning by reading & listening to texts, saving & reviewing vocab. Prerequisites are an installed LAMP/WAMP/MAMP (local web server & database) software and a modern web browser.
Live Lingua offers online classes via Skype with native, experienced and certified teachers in 11 of the most commonly spoken languages worldwide: Arabic, Chinese, English, French, German, Japanese, Korean, Portuguese, Russian and Spanish.