Bundle includes books on Linux security, shell scripting, a shell scripting cookbook, and one on embedded programming. Linux is one of the world’s most popular operating systems, so gaining knowledge in it can expand your knowledge base and increase your opportunities for future employment in the IT and developer community. This bundle is valued at $160, but with this special offer you can pay what you want. Bundle is available now for just $19.99 (regularly $590), a 96 percent discount.
Source: https://www.bleepingcomputer.com/offer/deals/increase-your-knowledge-of-linux-with-any-of-these-bundles/