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The Unix Tree

Welcome to the Unix Tree. Here you can browse the source code and manuals of various old versions of Unix. For every file, you can also find related files from other versions: this can help show how the different versions of Unix are related. Most of the Unix versions below come from theUnix Archive.

If you want to get a copy of all the files in the Unix Tree, please don't spider this website as it causes a high load. You can download a bzipped tarball of the files here.

Research Unix

These are the versions of Unix developed at Bell Laboratories, initially by Ken Thompson and Dennis Ritchie, later by many other of the researchers there.

USG/USL

Originally set up to support Unix internally, the Unix Support Group eventually became Unix System Laboratories, and developed the System III and System V commercial versions of Unix.

Other Early Unixes

As Unix was distributed non-commercially in the mid-1970s, many other institutions took the system and modified it. Many of the changes from these early variants were fed back into the research version of Unix.

Early BSDs

The early BSDs, 1BSD and 2BSD, were collections of commands and libraries like the Pascal system, the ex editor and the C-shell. Later systems such as 2.8BSD through to 2.11BSD were complete, installable, 16-bit systems with kernel source.

Early Networking

Apart from UCB, there were several organisations which took Unix and modified it to add networking features. Here are just a few of these modifications. Also look at the version of 4.1BSD with BBN's TCP/IP Code.

32-bit BSDs

3BSD was the first Unix to provide paged virtual memory. The 4BSDs went on to add features such as networking, the fast filesystem, vnodes & NFS, and they culminated in 4.4BSD-Lite which had been rewritten to contain no original Unix code.

Commercial Unixes

Many companies produced modified version of Unix, taking some or all of 32V, System III, System V, 4BSD, merging them and then value-adding to them.

Unix Derivatives

Several systems started with Unix source code, but this was written out over time so that no original Unix code remains. The best known examples are OpenSolaris, FreeBSD, NetBSD and OpenBSD.

Unix Clones

There have been many systems which implement the Unix system calls, library APIs and commands, but which did not include any original Unix source code. Here is a small selection.

Similarities between files are found using thectcomparetool running in default mode. For each file, the list of similar files is given in descending order of the total number of similar token runs.

The Unix Tree website is (c) 2010, Warren Toomey.