Lions' Commentary on UNIX 6th Edition, with Source Code
Encyclopedia
Lions' Commentary on UNIX 6th Edition, with Source Code by John Lions
(1976) contains the complete source code
of the 6th Edition
Unix
kernel plus a commentary. It is commonly referred to as the Lions book. Despite its age, it is still considered an excellent commentary on simple but high quality code.
For many years, the Lions Book was the only Unix kernel documentation available outside Bell Labs
. Although the license of 6th Edition allowed classroom use of the source code, the license of 7th Edition
specifically excluded such use, so the book spread by samizdat
. It was commonly held to be the most copied book in computer science
.
The book was reprinted in 1996 by Peer-To-Peer Communications.
The code as presented will run on a PDP-11
/40 with RK-05 disk drive, LP-11 line printer interface, PCL-11 paper tape writer and KL-11 terminal interface, or a suitable PDP-11 emulator, such as SIMH
.
A Commentary on the Unix Operating System starts with notes on Unix and other useful documentation (the Unix manual pages, DEC
hardware manuals and so on), a section on the architecture of the PDP-11 and a chapter on how to read C
programs. The source commentary follows, divided into the same sections as the code. The book ends with suggested exercises for the student.
As Lions explains, this commentary supplements the comments in the source. It is possible to understand the code without the extra commentary, and the reader is advised to do so and only read the notes as needed. The commentary also remarks on how the code might be improved.
courses (6.602B and 6.657G) at the University of New South Wales Department of Computer Science.
UNIX News March 1977 announced the availability of the book to Unix licensees. Lions had trouble keeping up with its popularity, and by 1978 it was available only from Bell Labs.
When AT&T announced Unix Version 7
at USENIX
in June 1979, the academic/research license no longer automatically permitted classroom use. Thus, licensees were no longer able to use the Lions notes for classes on operating system
s.
However, thousands of computer science students around the world spread photocopies. As they could not study it legally in class, they would sometimes meet after hours to discuss the book. Many pioneers of Unix and open source
had a treasured multiple-generation photocopy.
Other follow-on effects of the license change included Andrew S. Tanenbaum
creating Minix
. As Tanenbaum said in Operating Systems (1987): "When AT&T released Version 7, it began to realize that UNIX was a valuable commercial product, so it issued Version 7 with a license that prohibited the source code from being studied in courses, in order to avoid endangering its status as a trade secret. Many universities complied by simply dropping the study of UNIX, and teaching only theory."
Various Unix people, particularly Peter H. Salus
, Dennis Ritchie
and Berny Goodheart
, lobbied Unix's various owners (AT&T, Novell
, the Santa Cruz Operation) for many years to allow the book to be published officially. In 1996, the Santa Cruz Operation finally authorised the release of the twenty-year-old 6th Edition source code (along with the source code of other versions of "Ancient UNIX"), and the full code plus the 1977 version of the commentary was published by Peer-To-Peer Communications (ISBN 1-57398-013-7). The reissue includes commentary from Michael Tilson (SCO), Peter Salus, Dennis Ritchie, Ken Thompson, Peter Collinson, Greg Rose, Mike O'Dell, Berny Goodheart and Peter Reintjes.
became the inaugural John Lions Chair.
John Lions
John Lions was an Australian computer scientist. He is best known as the author of Lions' Commentary on UNIX 6th Edition, with Source Code, commonly known as the Lions Book.-Early life:...
(1976) contains the complete source code
Source code
In computer science, source code is text written using the format and syntax of the programming language that it is being written in. Such a language is specially designed to facilitate the work of computer programmers, who specify the actions to be performed by a computer mostly by writing source...
of the 6th Edition
Version 6 Unix
Sixth Edition Unix, also called Version 6 Unix or just V6, was the first version of the Unix operating system to see wide release outside Bell Labs. It was released in May 1975 and, like its direct predecessor, targeted the DEC PDP-11 family of minicomputers...
Unix
Unix
Unix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna...
kernel plus a commentary. It is commonly referred to as the Lions book. Despite its age, it is still considered an excellent commentary on simple but high quality code.
For many years, the Lions Book was the only Unix kernel documentation available outside Bell Labs
Bell Labs
Bell Laboratories is the research and development subsidiary of the French-owned Alcatel-Lucent and previously of the American Telephone & Telegraph Company , half-owned through its Western Electric manufacturing subsidiary.Bell Laboratories operates its...
. Although the license of 6th Edition allowed classroom use of the source code, the license of 7th Edition
Version 7 Unix
Seventh Edition Unix, also called Version 7 Unix, Version 7 or just V7, was an important early release of the Unix operating system. V7, released in 1979, was the last Bell Laboratories release to see widespread distribution before the commercialization of Unix by AT&T in the early 1980s...
specifically excluded such use, so the book spread by samizdat
Samizdat
Samizdat was a key form of dissident activity across the Soviet bloc in which individuals reproduced censored publications by hand and passed the documents from reader to reader...
. It was commonly held to be the most copied book in computer science
Computer science
Computer science or computing science is the study of the theoretical foundations of information and computation and of practical techniques for their implementation and application in computer systems...
.
The book was reprinted in 1996 by Peer-To-Peer Communications.
Synopsis
Unix Operating System Source Code Level Six is the kernel source code, lightly edited by Lions to better separate the functionality — system initialization and process management, interrupts and system calls, basic I/O, file systems and pipes and character devices. All procedures and symbols are listed alphabetically with a cross reference.The code as presented will run on a PDP-11
PDP-11
The PDP-11 was a series of 16-bit minicomputers sold by Digital Equipment Corporation from 1970 into the 1990s, one of a succession of products in the PDP series. The PDP-11 replaced the PDP-8 in many real-time applications, although both product lines lived in parallel for more than 10 years...
/40 with RK-05 disk drive, LP-11 line printer interface, PCL-11 paper tape writer and KL-11 terminal interface, or a suitable PDP-11 emulator, such as SIMH
SIMH
SIMH is a highly portable, multi-system emulator which runs on Windows, Linux, Mac OS X, FreeBSD, OpenBSD, NetBSD, OpenVMS, and other operating systems...
.
A Commentary on the Unix Operating System starts with notes on Unix and other useful documentation (the Unix manual pages, DEC
Digital Equipment Corporation
Digital Equipment Corporation was a major American company in the computer industry and a leading vendor of computer systems, software and peripherals from the 1960s to the 1990s...
hardware manuals and so on), a section on the architecture of the PDP-11 and a chapter on how to read C
C (programming language)
C is a general-purpose computer programming language developed between 1969 and 1973 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system....
programs. The source commentary follows, divided into the same sections as the code. The book ends with suggested exercises for the student.
As Lions explains, this commentary supplements the comments in the source. It is possible to understand the code without the extra commentary, and the reader is advised to do so and only read the notes as needed. The commentary also remarks on how the code might be improved.
History
The source code and commentary were originally produced in May 1976 as a set of lecture notes for Lions' computer scienceComputer science
Computer science or computing science is the study of the theoretical foundations of information and computation and of practical techniques for their implementation and application in computer systems...
courses (6.602B and 6.657G) at the University of New South Wales Department of Computer Science.
UNIX News March 1977 announced the availability of the book to Unix licensees. Lions had trouble keeping up with its popularity, and by 1978 it was available only from Bell Labs.
When AT&T announced Unix Version 7
Version 7 Unix
Seventh Edition Unix, also called Version 7 Unix, Version 7 or just V7, was an important early release of the Unix operating system. V7, released in 1979, was the last Bell Laboratories release to see widespread distribution before the commercialization of Unix by AT&T in the early 1980s...
at USENIX
USENIX
-External links:* *...
in June 1979, the academic/research license no longer automatically permitted classroom use. Thus, licensees were no longer able to use the Lions notes for classes on operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
s.
However, thousands of computer science students around the world spread photocopies. As they could not study it legally in class, they would sometimes meet after hours to discuss the book. Many pioneers of Unix and open source
Open source
The term open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology...
had a treasured multiple-generation photocopy.
Other follow-on effects of the license change included Andrew S. Tanenbaum
Andrew S. Tanenbaum
Andrew Stuart "Andy" Tanenbaum is a professor of computer science at the Vrije Universiteit, Amsterdam in the Netherlands. He is best known as the author of MINIX, a free Unix-like operating system for teaching purposes, and for his computer science textbooks, regarded as standard texts in the...
creating Minix
Minix
MINIX is a Unix-like computer operating system based on a microkernel architecture created by Andrew S. Tanenbaum for educational purposes; MINIX also inspired the creation of the Linux kernel....
. As Tanenbaum said in Operating Systems (1987): "When AT&T released Version 7, it began to realize that UNIX was a valuable commercial product, so it issued Version 7 with a license that prohibited the source code from being studied in courses, in order to avoid endangering its status as a trade secret. Many universities complied by simply dropping the study of UNIX, and teaching only theory."
Various Unix people, particularly Peter H. Salus
Peter H. Salus
Peter H. Salus is a linguist, computer scientist, historian of technology, author in many fields, and an editor of books and journals. He has conducted research in germanistics, language acquisition, and computer languages...
, Dennis Ritchie
Dennis Ritchie
Dennis MacAlistair Ritchie , was an American computer scientist who "helped shape the digital era." He created the C programming language and, with long-time colleague Ken Thompson, the UNIX operating system...
and Berny Goodheart
Berny Goodheart
Berny Goodheart is a computer scientist and author. He is best known for his books about the Unix operating system. He has also worked extensively with the Unix kernel, particularly porting it to new hardware platforms.He started working with Unix in 1977...
, lobbied Unix's various owners (AT&T, Novell
Novell
Novell, Inc. is a multinational software and services company. It is a wholly owned subsidiary of The Attachmate Group. It specializes in network operating systems, such as Novell NetWare; systems management solutions, such as Novell ZENworks; and collaboration solutions, such as Novell Groupwise...
, the Santa Cruz Operation) for many years to allow the book to be published officially. In 1996, the Santa Cruz Operation finally authorised the release of the twenty-year-old 6th Edition source code (along with the source code of other versions of "Ancient UNIX"), and the full code plus the 1977 version of the commentary was published by Peer-To-Peer Communications (ISBN 1-57398-013-7). The reissue includes commentary from Michael Tilson (SCO), Peter Salus, Dennis Ritchie, Ken Thompson, Peter Collinson, Greg Rose, Mike O'Dell, Berny Goodheart and Peter Reintjes.
Review quote
John Lions Chair in Computer Science
After his death, John O'Brien, Steve Jenkin, Chris Maltby and Greg Rose, former students of Lions, commenced a campaign to raise funds to create a chair in his name at UNSW, the John Lions Chair in Computer Science in the School of Computer Science and Engineering. With donations from many UNSW alumni, corporations, Usenix, Linux Australia, the chair was created in 2006, becoming the first chair at UNSW funded by contributions from alumni. In 2009, Gernot HeiserGernot Heiser
Gernot Heiser is a Scientia Professor and the John Lions Chair for operating systems at the University of New South Wales . He is also leader of the at NICTA. In 2006 he co-founded Open Kernel Labs to commercialise his L4 microkernel technology...
became the inaugural John Lions Chair.
John Lions Garden
In 2002, UNSW dedicated the John Lions Garden in front of the new Computer Science and Engineering building to Lions' memory.Further reading
- Andrew S. TanenbaumAndrew S. TanenbaumAndrew Stuart "Andy" Tanenbaum is a professor of computer science at the Vrije Universiteit, Amsterdam in the Netherlands. He is best known as the author of MINIX, a free Unix-like operating system for teaching purposes, and for his computer science textbooks, regarded as standard texts in the...
, Operating Systems: Design and Implementation, (Prentice-Hall, ISBN 0-13-637331-3, June 1987) - Lions Book (Jargon FileJargon FileThe Jargon File is a glossary of computer programmer slang. The original Jargon File was a collection of terms from technical cultures such as the MIT AI Lab, the Stanford AI Lab and others of the old ARPANET AI/LISP/PDP-10 communities, including Bolt, Beranek and Newman, Carnegie Mellon...
, references ISBN 1-57398-013-7) - Code Critic (Rachel Chalmers, Salon 30 November 1999)
- Peter H. SalusPeter H. SalusPeter H. Salus is a linguist, computer scientist, historian of technology, author in many fields, and an editor of books and journals. He has conducted research in germanistics, language acquisition, and computer languages...
, The Daemon, The GNU and the Penguin, ch. 6: 1979 (preprint, 2005) - Brian W. Kernighan and Dennis RitchieDennis RitchieDennis MacAlistair Ritchie , was an American computer scientist who "helped shape the digital era." He created the C programming language and, with long-time colleague Ken Thompson, the UNIX operating system...
, The C Programming LanguageThe C Programming Language (book)The C Programming Language is a well-known programming book written by Brian Kernighan and Dennis Ritchie, the latter of whom originally designed and implemented the language, as well as co-designed the Unix operating system with which development of the language was closely intertwined...
, ISBN 0-13-110362-8
External links
- Peer-To-Peer Communications website, product page
- UNSW School of Computer Science & Engineering
- Complete commentary in PDFPortable Document FormatPortable Document Format is an open standard for document exchange. This file format, created by Adobe Systems in 1993, is used for representing documents in a manner independent of application software, hardware, and operating systems....
, PostScriptPostScriptPostScript is a dynamically typed concatenative programming language created by John Warnock and Charles Geschke in 1982. It is best known for its use as a page description language in the electronic and desktop publishing areas. Adobe PostScript 3 is also the worldwide printing and imaging...
, and LaTeXLaTeXLaTeX is a document markup language and document preparation system for the TeX typesetting program. Within the typesetting system, its name is styled as . The term LaTeX refers only to the language in which documents are written, not to the editor used to write those documents. In order to...
formats - Complete source codeSource codeIn computer science, source code is text written using the format and syntax of the programming language that it is being written in. Such a language is specially designed to facilitate the work of computer programmers, who specify the actions to be performed by a computer mostly by writing source...
listing available (6th Edition UnixUnixUnix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna...
source codeSource codeIn computer science, source code is text written using the format and syntax of the programming language that it is being written in. Such a language is specially designed to facilitate the work of computer programmers, who specify the actions to be performed by a computer mostly by writing source...
as modified by John LionsJohn LionsJohn Lions was an Australian computer scientist. He is best known as the author of Lions' Commentary on UNIX 6th Edition, with Source Code, commonly known as the Lions Book.-Early life:...
) in PDF and HTML formats. - Ersatz 11 (commercial), SIMH (free), and other PDP-11 hardware emulators