Although Linux has no Unix source code, it's popular among university CS departments because it's free of charge, runs on a wide variety of hardware, and professors are already familiar with Linux.

It compared source code from the Unix System V release 4.1 software that SGI has licensed from SCO with a version of the Linux kernel released this June, SGI said.

SCO’s first example, some code used to manage the computer’s memory, was actually released under an open source license by SCO itself in 2002 and could be legitimately used in Linux, Perens said.

Specifically, SCO claims that IBM’s 1985 Unix license, originally signed with AT&T, but subsequently transferred to SCO, prevents IBM from distributing software derived from the Unix code base.

News of Novell’s copyright registration surfaced on the same day that SCO announced that it was requiring its 6,000 Unix licensees to certify that they are complying with their Unix source-code ...

Although Sun has broader rights than do other Unix licensees such as IBM and Hewlett-Packard, it doesn't have the right to release Unix source code or Sun modifications to it as open-source ...

In addition, Novell also demanded that SCO reveal where Unix source code has been copied into Linux, attacking a broader claim in which SCO has accused Linux companies of illegally copying Unix ...

In the early days of high-performance computing, the major tech companies of the day each invested heavily in developing their own closed source versions of Unix. It was hard to imagine at the time ...