Brian Kernighan is a professor of computer science at Princeton University. He co-authored the C Programming Language with Dennis Ritchie (creator of C) and has written a lot of books on programming, computers, and life including the Practice of Programming, the Go Programming Language, his latest UNIX: A History and a Memoir. He co-created AWK, the text processing language used by Linux folks like myself. He co-designed AMPL, an algebraic modeling language for large-scale optimization.

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EPISODE LINKS:
Brian's website: https://www.cs.princeton.edu/~bwk/
Unix: A History and a Memoir (book): https://amzn.to/3fFJ1yM
Understanding the Digital World (book): https://amzn.to/30ktBJI

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OUTLINE:
0:00 - Introduction
4:24 - UNIX early days
22:09 - Unix philosophy
31:54 - Is programming art or science?
35:18 - AWK
42:03 - Programming setup
46:39 - History of programming languages
52:48 - C programming language
58:44 - Go language
1:01:57 - Learning new programming languages
1:04:57 - Javascript
1:08:16 - Variety of programming languages
1:10:30 - AMPL
1:18:01 - Graph theory
1:22:20 - AI in 1964
1:27:50 - Future of AI
1:29:47 - Moore's law
1:32:54 - Computers in our world
1:40:37 - Life

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The following is a conversation with Brian Kernighan, a professor of computer science at Princeton University.

He was a key figure in the computer science community in the early Unix days, alongside Unix creators Ken Thompson and Dennis Ritchie.

He co-authored the C programming language with Dennis Ritchie, the creator of C, and has written a lot of books on programming, computers, and life, including the practice of programming, the Go programming language, and his latest, Unix, a history, and a Memoir.

He co-created AWK, the text processing language used by Linux folks like myself.

He co-designed Ample, an algebraic modeling language that I personally love and have used a lot in my life for large scale optimization.

I think I can keep going for a long time with his creations and accomplishments, which is funny because given all that, he's 1 of the most humble and kind people I've spoken to on this podcast.

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And now, here's my conversation with Brian Kernighan.

Unix started being developed 50 years ago, maybe more than 50 years ago.

Can you tell the story, like you describe in your new book, of how Unix was created?

Ha, if I can remember that far back, it was some while ago.

So I think the gist of it is that at Bell Labs In 1969, there were a group of people who had just finished working on the Multics project, which was itself a follow-on to CTSS.

So we can go back sort of an infinite regress in time, but the CTSS was a very, very, very nice time-sharing system.

I actually used it as that summer I spent in Cambridge in 1966.

So CTSS looked like kind of like a standard time-sharing system.

Certainly at the time, it was the only time-sharing.

In the beginning was the word and the word was the sound.

If we go back into, let's call it the 1950s and early 1960s, most computing was done on very big computers, physically big, although not terribly powerful by today's standards, that were maintained in very large rooms.

And you use things like punch cards to write your programs on and talk to them.

So you would take a deck of cards, write your program on it, send it over a counter, hand it to an operator.

And some while later back would come something that said, Oh, you made a mistake.

So the idea of time-sharing was that you take basically that same computer, but connect to it with something that looked like an electric typewriter.

That could be a long distance away, it could be close, but fundamentally what the operating system did was to give each person who was connected to it and wanting to do something a small slice of time to do a particular job.

So I might be editing a file, so I would be typing.

And every time I hit a keystroke, the operating system would wake up and said, oh, he typed character, let me remember that.

And then he'd go back to doing something else.

So it'd be going around and around a group of people who were trying to get something done, giving each a small slice of time and giving them each the illusion that they pretty much had the whole machine to themselves.

And hence, time sharing, that is sharing the computing time resource of the computer among a number of people who were doing it.

Without the individual people being aware that there's others, in a sense, the illusion, the feelings that the machine is your own.

Yes, you had, if it were well done, and if it were fast enough and other people weren't doing too much, you did have the illusion that you had the whole machine to yourself.

And it was very much better than the punch card model.

And so CTSS, the compatible time-sharing system, was I think arguably the first of these.

It was done, I guess, technically in 64, something like that.

It ran on an IBM 7094, slightly modified to have twice as much memory as the norm.

It had 2 banks of 32K words instead of 1.

Each word was 36 bits, so call it, you know, about 150 kilobytes times 2.

So, by today's standards, that's down in the noise.

But at the time, that was a lot of memory and memory was expensive.

So CTSS was just a wonderful environment to work on.

It was done by the people at MIT, led by Fernando Corbato, Corby, who died just earlier this year, and a bunch of other folks.

So I spent the summer of 66 working on that.

Had a great time, met a lot of really nice people, and indirectly knew of people at Bell Labs who were also working on a follow-on to CTSS that was called Multics.

So Multics was meant to be the system that would do everything that CTSS did, but do it better for a larger population.

Now the actual time sharing, the scheduling, how much, what's the algorithm that performs the scheduling?

I think the basic idea was nothing more than who all wants to get something done.

Suppose that things are very quiet in the middle of the night, then I get all the time that I want.

Suppose that you and I are contending at high noon for something like that, then probably the simplest algorithm is a round robin 1 that gives you a bit of time, gives me a bit of time.

Are you text editing or are you compiling or something?

And then we might adjust the scheduler according to things like that.

So, okay, so Multics was trying to just do some of the, clean it up a little bit.

Well, it was meant to be much more than that.

So Multics was the multiplexed information and computing service, and it was meant to be a very large thing that would provide computing utility, something that where you could actually think of it as just a plug in the wall service, sort of like cloud computing today, same idea, but 50 odd years earlier.

And so what Multics offered was a richer operating system environment, a piece of hardware that was better designed for doing the kind of sharing of resources, and presumably lots of other things.

Do you think people at that time had the dream of what cloud computing is starting to become now, which is computing is everywhere that you can just plug in almost, you know, and you never know how the magic works.

You just kind of plug in, add your little computation that you need to perform and it does it.

But my sense is, given that it was over 50 years ago, yeah, they had that idea that it was an information utility, that it was something where if you had a computing task to do, you could just go and do it.

Now I'm betting that they didn't have the same view of computing for the masses, let's call it, the idea that your grandmother would be shopping on Amazon.

But if your grandmother were a programmer, it might be very easy for her to go and use this kind of utility.

What was your dream of computers at that time?

What did you see as the future of computers?

Could you have predicted what computers are today?

It was a dream job in the sense that I really enjoyed what I was doing.

I was surrounded by really, really nice people.

Cambridge is a very fine city to live in in the summer, less so in the winter when it snows, but in the summer It was a delightful time.

And so I really enjoyed all of that stuff and I learned things.

And I think the good fortune of being there for summer led me then to get a summer job at Bell Labs the following summer.

And that was quite useful for the future.

So this Bell Labs is this magical, legendary place.

And can you start talking about that journey towards Unix at Bell Labs?

Yeah, so Bell Labs is physically scattered around, at the time, scattered around New Jersey.

The primary location was in a town called Murray Hill, or a location called Murray Hill.

It was actually across the boundary between 2 small towns in New Jersey called New Providence and Berkeley Heights.

Think of it as about 15, 20 miles straight west of New York City, and therefore about an hour north of here in Princeton.

And at that time, it had make up a number, 3,000 or 4,000 people there, many of whom had PhDs and mostly doing physical sciences, chemistry, physics, materials, kinds of things, but very strong math and rapidly growing interest in computing as people realized you could do things with computers that you might not have been able to do before.

You could replace labs with computers that had worked on models of what was going on.

And again, I wasn't a permanent employee there.

I mean, if you could just linger on it a little bit, what was in the air there?

Because some of the, the number of Nobel Prizes, the number of Turing Awards, and just legendary computer scientists that come from there, inventions including, developments including Unix, it's just, it's unbelievable.

So was there something special about that place?

Oh, I think there was very definitely something special.

I mentioned the number of people, it's a very large number of people, very highly skilled and working in an environment where there was always something interesting to work on because the goal of Bell Labs, which was a small part of AT&T, which provided basically the country's phone service, The goal of AT&T was to provide service for everybody.

And the goal of Bell Labs was to try and make that service keep getting better.

And that meant doing research on a lot of different things.

Physical devices like the transistor or fiber, optical cables or microwave systems, all of these things the labs worked on.

And it was kind of just the beginning of real boom times in computing as well.

Because when I was there, I went there first in 66.

So computing was at that point fairly young and so people were discovering that you could do lots of things with computers.

in spite of having an enormous number of really good ideas and lots of good people working on it fundamentally didn't live up, at least in the short run, and I think ultimately really ever, to its goal of being this information utility.

It was too expensive and certainly what was promised was delivered much too late.

And so in roughly the beginning of 1969, Bell Labs pulled out of the project.

The project at that point had included MIT, Bell Labs, and General Electric.

General Electric made computers, So General Electric was the hardware operation.

So Bell Labs, realizing this wasn't going anywhere on a timescale they cared about, pulled out a project.

And this left several people with an acquired taste for really, really nice computing environments, but no computing environment.

And so they started thinking about what could you do if you're going to design a new operating system that would provide the same kind of comfortable computing as CTSS had, but also the facilities of something like Multics sort of brought forward.

And at the same time, Ken Thompson found what is characterized as a little used PDP-7, where he started to do experiments with file systems, just how do you store information on a computer in an efficient way.

And then this famous story that his wife went away to California for 3 weeks taking their one-year-old son, and 3 weeks, and he sat down and wrote an operating system, which ultimately became Unix.

So software productivity was good in those days.

It was 1 of early machines made by Digital Equipment Corporation, DEC, And it was a mini computer, so-called.

It had, I would have to look up the numbers exactly, but it had a very small amount of memory, maybe 16K, 16-bit words or something like that, relatively slow, probably not super expensive.

Maybe, again, making this up, I'd have to look it up, $100,000 or something like that.

Which is not super expensive in those days, right?

It was expensive, it was enough that you and I probably wouldn't be able to buy 1, but a modest group of people could get together.

But in any case, it came out, if I recall, in 1964.

So by 1969, it was getting a little obsolete, and that's why it was little used.

If you can sort of comment, what do you think it's like to write an operating system like that?

So that process that Ken went through in 3 weeks, because you were, I mean, you're a part of that process.

You contributed a lot to Unix's early development.

So what do you think it takes to do that first step, that first kind of, from design to reality on the PDP?

I have never written operating system code.

And this first 1 wasn't very big, but it's something that lets you run processes of some, lets you execute some kind of code that has been written.

It lets you store information for periods of time so that it doesn't go away when you turn the power off or reboot or something like that.

And there's a kind of a core set of tools that are technically not part of an operating system, but you probably need them.

In this case, Ken wrote an assembler for the PDP-7 that worked.

He needed a text editor so that he could actually create text.

He had the file system stuff that he had been working on and then the rest of it was just a way to load things, executable code from the file system into the memory, give it control and then recover control when it was finished or in some other way quit.

What was the code written in the primarily the programming language, was it in assembly?

These things were assembly language until probably the, call it 1973 or 74, something like that.

Forgive me if it's a dumb question, but it feels like a daunting task to write any kind of complex system in assembly.

It feels like impossible to do any kind of what we think of as software engineering with assembly because to work in a big picture sort of.

It's been a long time since I wrote assembly language.

It is absolutely true that in assembly language, if you make a mistake, nobody tells you.

Well, there could be debuggers, but that's the same problem, right?

How do you actually get something that will help you debug it?

So part of it is an ability to see the big picture.

Now, these systems were not big in the sense that today's pictures are.

So the big picture was in some sense more manageable.

I mean, then realistically, there's an enormous variation in the capabilities of programmers.

And Ken Thompson, who did that first 1, is kind of the singularity, in my experience, of programmers, with no disrespect to you or even to me.

It's a fascinating thing that there are unique stars in particular in the programming space and at a particular time.

You know, the time matters too, the timing of when that person comes along.

There's this weird timing that happens that and then all of a sudden something beautiful is created.

I mean, how does it make you feel that there's a system that was created in 3 weeks or maybe you can even say on a whim, but not really, but of course quickly, that is now, you could think of most of the computers in the world run on a Unix-like system.

How do you, like, if you kind of zoom from the alien perspective, if you were just observing Earth, that all of a sudden these computers took over the world and they started from this little initial seed of Unix.

It's quite surprising, and you asked earlier about prediction.

There's no way you could predict that kind of evolution.

And I don't know whether it was inevitable or just a whole sequence of blind luck.

And so I look at it and think, gee, that's kind of neat.

I think the real question is, what does Ken think about that?

Because he's the guy arguably from whom it really came.

Tremendous contributions from Dennis Ritchie and then others around in that Bell Labs environment.

But if you had to pick a single person, that would be Ken.

So you've written a new book, Unix, a history and a memoir.

Are there some memorable human stories, funny or profound from that time that just kind of stand out?

And again, it's a question of can you resurrect them in real time?

But I think part of it was that Bell Labs at the time was a very special kind of place to work because there were a lot of interesting people and the environment was very, very open and free.

It was a very cooperative environment, very friendly environment.

And so if you had an interesting problem, you go and talk to somebody and they might help you with the solution.

And it was a kind of a fun environment too in which people did strange things and often tweaking the bureaucracy in 1 way or another.

I think most people didn't take too kindly to the bureaucracy and I'm sure the bureaucracy put up with an enormous amount that they didn't really want to.

So maybe to linger on it a little bit, do you have a sense of what the philosophy that characterizes Unix is, the design, not just the initial, but just carry through the years, just being there, being around it.

What's the fundamental philosophy behind the system?

I think 1 aspect of the fundamental philosophy was to provide an environment that made it easy to write or easier, productive to write programs.

So it was meant as a programmer environment.

It wasn't meant specifically as something to do some other kind of job.

For example, it was used extensively for word processing, but it wasn't designed as a word processing system.

It was used extensively for lab control, but it wasn't designed for that.

It was used extensively as a front end for big other systems, big dump systems, but it wasn't designed for that.

It was meant to be an environment where it was really easy to write programs.

So the programmers could be highly productive.

And there's some observation from Dennis Ritchie, I think at the end of the book, that says that from his standpoint, the real goal was to create a community where people could work as programmers on a system.

And I think in that sense, certainly for many, many years, it succeeded quite well at that.

And part of that is the technical aspects of, because it made it really easy to write programs, people did write interesting programs, those programs tended to be used by other programmers.

And so it was kind of a virtuous circle of more and more stuff coming out that was really good for programmers.

And you were part of that community of programmers.

So what was it like writing programs on that early Unix?

I'm not a terribly good programmer, but it was a lot of fun to write code.

And in the early days, there was an enormous amount of what you would today, I suppose, call low-hanging fruit.

People hadn't done things before, and this was this new environment, and the whole combination of nice tools and very responsive system and tremendous colleagues made it possible to write code.

You could have an idea In the morning, you could do an experiment with it.

You could have something limping along that night or the next day, and people would react to it, and they would say, oh, that's wonderful, but you really screwed up here.

And the feedback loop was then very, very short and tight.

And so a lot of things got developed fairly quickly that in many cases still exist today.

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Brian Kernighan: UNIX, C, AWK, AMPL, and Go Programming | Lex Fridman Podcast #109