The life and times of Professor John Lions
The story behind the most famous suppressed manuscript in computer history
Published on the 22 July 2024
“It is our hope that this book will be of interest and value to many students of the UNIX Time-sharing System.”
Professor John Lions could never have known how much of an understatement this would be when he wrote the preface to A Commentary on the Sixth Edition Unix Operating System.
Originally produced in May 1976 purely to assist students at UNSW Sydney studying Operating Systems, the ‘Lions book’ ultimately influenced hundreds of thousands, if not millions, of people around the world and had a profound impact on the very fundamentals of computer coding.
Key to its success was the way Lions was able to take a complicated topic and break it down to be easily understood. More than just a manual, the book gave users a real understanding of what the computer code was doing and why.
The Lions Book promoted the idea that computer code should be publicly accessible for anyone to study, review, modify and distribute as they wish. That notion became one of the sparks for the entire Open Source movement, inspiring collaboration, transparency and inclusivity across multiple generations of computer programmers – and many others in vastly different professions.
Open Source has ultimately driven innovations like Apple’s Mac OS X (based on UNIX) and Google’s Android (based on Linux), powering billions of devices worldwide every day.
Despite its acclaim, the popularity of the Lions Book drew scrutiny from AT&T, who became uncomfortable with the UNIX code being so openly analysed and banned classroom use in 1979.
Computer science students all around the world were not to be denied, however, and the small number of existing original versions were soon furtively photocopied. The book quickly gained a reputation as one of the most illicitly copied books of its time, with demand on the underground black-market continuing for two decades.
In 1996, efforts spearheaded by original UNIX developer Dennis Ritchie succeeded in re-authorising the Lions Book, and it went on to sell around 15,000 copies – unheard of for a book about 20-year-old code.
The Man Behind the Legend
Lions graduated from Sydney University in 1959 with a first-class honours degree in applied mathematics and obtained a PhD in control engineering from Cambridge in 1963. His career took him across the world before he returned to Sydney in 1972, where he joined UNSW as a senior lecturer in the Department of Computing.
Former students remember him as a fine teacher and a good friend, whose door was always open for a chat or advice about a project or business idea.
After his death on 5th December 1998, aged just 61, the Lions Garden outside the Computer Science Building at UNSW was dedicated in 2002.
In 2006, a group of UNSW alumni established the John Lions Chair of Operating Systems, thanks to donations from a community that held Lions dear to their heart. Scientia Professor Gernot Heiser became the inaugural chair in 2009 and retains that position to the present day.
“In John Lions, we celebrate a man whose passion for understanding and teaching has left an indelible mark on the world of computing. His work remains a beacon of clarity and insight, guiding both current and future generations in the art of system-level programming. Through his commentary, John achieved a form of immortality, ensuring that his wisdom and dedication to the field will never be forgotten,” says John O’Brien, chair of the John Lions Committee.
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