The SCO Group last week stepped up its campaign to enforce its patent infringement claims against Linux by suing automaker DaimlerChrysler and auto parts retailer AutoZone. The litigious software vendors claims the two corporations are violating the company's licensing restrictions by using Linux.\u00a0In its suit against DaimlerChrysler, which is an SCO customer, the vendor wants the automaker to certify that it hasn't violated its SCO Unix licensing agreement by using Linux machines - which SCO claims use copyright-protected Unix code. DaimlerChrysler uses a Linux cluster to simulate automobile crash tests and for other computer modeling applications.In the AutoZone case, SCO is claiming that the company has violated Unix copyrights by deploying 3,000 Red Hat Linux-based terminals throughout its U.S. stores.The latest move by SCO comes after the firm's $1 billion lawsuit against IBM, claming that it hijacked Unix code and put it into the current Linux kernel. Last year, SCO sent letters to 1,000 large enterprises, warning them to stop using Linux on the basis of SCO's legal claims. It also started selling $750 licenses that would allow users to run Linux without legal risk from SCO's lawyers.Don't forget that The SCO Group was formerly known as the Linux vendor Caldera, which in 2000 had purchased low-end Unix vendor Santa Cruz Operation (SCO), then the disputed owner of the copyright to Unix System V, on which most Unix systems are based. The company then reverted back to the SCO name in 2003, and shortly after, dropped its Linux product lines and refocused its business plan on collecting Unix licensing fees and royalties from Linux users and vendors.\u00a0After all this, all the company has gained so far is a lot of red ink, while putting a target on its back for Internet vigilantes. SCO reported a $1.5 million loss in its last fiscal quarter, doubling its loss of $724,000 from the same quarter a year ago. In January, SCO's Web site came under a denial-of-service attack that shut the vendor's online presence down for two days.