Learning the UNIX Operating System, 4th Edition by Jerry Peek, Grace Todino, and John Strang Here are the changes made in the 3/99 reprint: (viii) Under "Versions of Unix," line 4 read: "BSD 4.4" but now reads: "4.4BSD" Also, same paragraph, line 6 read: "The freely available versions include Linux and Free BSD." It now reads: "The freely available versions include Linux and FreeBSD (FreeBSD is based on 4.4BSD-Lite)."