The guest
Brian Kernighan: Princeton computer science professor and Bell Labs veteran who co-authored the C programming language with Dennis Ritchie, co-created AWK and AMPL, and was a key figure in the early UNIX community.
What this episode covers
Brian Kernighan walks Lex Fridman through the birth of UNIX at Bell Labs in 1969, including Ken Thompson writing the first version in three weeks on a PDP-7. He explains the philosophy behind UNIX, the design and lasting success of C, and his work on AWK and the AMPL optimization-modeling language. The conversation traces the history of programming languages from assembly to functional languages, and Kernighan repeatedly downplays his own contributions with characteristic humility. The episode closes on broader reflections about AI, Moore's law, privacy, and how computing has reshaped human connection.
Recommended on this episode
ProductRecommended
Sam text editor
Rob Pike
“editor I use mostly Sam”
“editor I use mostly Sam which is an editor that Rob Pike wrote long ago at Bell Labs”— guest
The guest's own work
BookBy the guestISBN verified
UNIX: A History and a Memoir
Brian Kernighan
“has written a lot of books on programming computers and life including the practice of programming the goal programming language and his latest UNIX a history”— Lex Fridman
BookBy the guestISBN verified
The Practice of Programming
Brian Kernighan
“has written a lot of books on programming computers and life including the practice of programming the goal programming language and his latest UNIX a history”— Lex Fridman
BookBy the guestISBN verified
The Go Programming Language
Brian Kernighan
“has written a lot of books on programming computers and life including the practice of programming the goal programming language and his latest UNIX a history”— Lex Fridman
BookBy the guestISBN verified
The C Programming Language
Brian Kernighan and Dennis Ritchie
“you wrote a book C programming language and C is probably one of the most important languages in the history of programming languages”— Lex Fridman
BookBy the guestISBN verified
AMPL: A Modeling Language for Mathematical Programming
Robert Fourer, David Gay, Brian Kernighan
“we wrote a couple of versions of a book on which is one of the greatest books ever written I love that book”— guest
Also referenced (named, not recommended)
ProductReferenced
MacBook Air (13-inch)
Apple
“I have a at this point a 13-inch MacBook Air which I used because it's kind of a reasonable balance of the various things I need”— guest
ProductReferenced
iMac
Apple
“I have a big iMac in my office that I use from time to time as well especially when I need a big screen”— guest
BookReferenced
Computers and Thought
Edward Feigenbaum and Julian Feldman
“there's a wonderful collection of papers called computers and thought that was published and about that era and people were very optimistic”— guest
Big reveals from this episode
- Kernighan insists he never wrote any operating system code and had nothing to do with the original UNIX kernel.
- He calls Ken Thompson 'the singularity' among programmers, several leagues above himself or anyone else.
- Kernighan recounts struggling with Rust for days due to rapidly changing, inconsistent documentation when he tried his test program.
- He reveals AMPL's acclaimed book was typeset in troff, a Bell Labs formatter that predates TeX by 5 to 10 years.
- Asked whether P equals NP, he bets no, and shares Jeff Dean's joke that it's true only if P is 0 or N is 1.
- He says he realized early on with John Hopcroft that he 'was not cut out' for theoretical computer science, steering him toward programming and books.
- Kernighan agrees JavaScript was once considered possibly the ugliest language yet may be taking over both back and front ends.
Worth remembering
- Early computing meant handing a deck of punch cards over a counter and waiting hours to learn you made a mistake.
- CTSS, arguably the first time-sharing system, ran on an IBM 7090 with just two banks of 32K words of memory.
- Ken Thompson wrote the first UNIX in three weeks while his wife was away in California with their one-year-old son.
- UNIX's efficiency came from being built on extremely modest hardware, forcing minimal, general mechanisms.
- Kernighan attributes C's longevity to a sweet spot between expressiveness and efficiency, plus its bundling with UNIX.
- He twisted Dennis Ritchie's arm to co-write the C book, and credits Ritchie's reference manual as a model of clear prose.
- Go's standout feature is its concurrency model, based on Tony Hoare's communicating sequential processes from 40-plus years ago.
- Kernighan laments modern programming's reliance on downloading massive opaque libraries via pip and npm with no recourse when they break.
- About a dozen languages account for roughly 95% of all programming, while around 2000 languages remain in marginal use.
- The episode ends with Kernighan's famous maxim: don't comment bad code, rewrite it.
More from Lex Fridman
All 5460 recommended