Demand for Linux experience now outpaces the need for UNIX in the marketplace. As of last November Linux, which has an almost a cult-like following, was running 91 percent of the world’s supercomputers. A search this morning on Dice returned more than 10,000 positions that request some level of proficiency. The market has gotten so tight that a few employers have started offering premiums for highly skilled professionals. PenguinAt work in a variety of applications and industries, Linux powers everything from animation and special effects systems in Hollywood to operating machines that milk cows and others that brew coffee. Within the next four years, the number of mobile users using Linux is expected to reach 4.9 billion. The Linux Foundation estimates that more than 500 companies are participating in development projects. So, how can you acquire Linux skills without spending a fortune?