# Doug McIlroy

Malcolm Douglas McIlroy (born 1932) is an American mathematician, engineer, and programmer, best known for having originally developed Unix pipes, software componentry, and several Unix tools, such as spell, diff, sort, join, graph, speak, and tr.

## Quotes

* This is the Unix philosophy: Write programs that do one thing and do it well. Write programs to work together. Write programs to handle text streams, because that is a universal interface.
** Doug McIlroy (2003). The Art of Unix Programming: Basics of the Unix Philosophy
* The notion of "intricate and beautiful complexities" is almost an oxymoron. Unix programmers vie with each other for "simple and beautiful" honors — a point that's implicit in these rules, but is well worth making overt.
** Doug McIlroy (2003). The Art of Unix Programming: Basics of the Unix Philosophy
* Word and Excel and PowerPoint and other Microsoft programs have intimate — one might say promiscuous — knowledge of each others' internals. In Unix, one tries to design programs to operate not specifically with each other, but with programs as yet unthought of.
** Doug McIlroy (2003). The Art of Unix Programming: The Elements of Operating-System Style
* Everything was small... and my heart sinks for Linux when I see the size of it. [...] The manual page, which really used to be a manual page, is now a small volume, with a thousand options... We used to sit around in the Unix Room saying, 'What can we throw out? Why is there this option?' It's often because there is some deficiency in the basic design — you didn't really hit the right design point. Instead of adding an option, think about what was forcing you to add that option.
** Doug McIlroy (2005). Ancestry of Linux — How the Fun Began
* Ritchie and Thompson made an amazing team; and they played Unix and C like a fine instrument. They sometimes divided up work almost on a subroutine-by-subroutine basis with such rapport that it almost seemed like the work of a single person. In fact, as Dennis has recounted, they once got their signals crossed and both wrote the same subroutine. The two versions did not merely compute the same result, they did it with identical source code! Their output was prodigious. Once I counted how much production code they had written in the preceding year − 100,000 lines! Prodigious didn’t mean slapdash. Ken and Dennis have unerring design sense. They write code that works, code that can be read, code that can evolve.
** Doug McIlroy (2011). Remarks for Japan Prize award ceremony for Dennis Ritchie, May 19, 2011, Murray Hill, NJ
* I don't know the counts of Unix and Linux servers. I do know that my heart sinks whenever I look under the hood in Linux. It is has been so overfed by loving hands. Over 240 system calls! Gigabytes of source! A C compiler with a 250-page user manual (not counting the language definition)! A simple page turner, 'less,' has over 40 options and 60 commands! It's proof that open-source can breed monsters just like the commercial pros. Miraculously, though, this monster works.
** Doug McIlroy (2013). In their own words: Unix pioneers remember the good times

## Quotes about Doug McIlroy

* ... speaking of Doug, he's the unsung hero of Unix. He was manager of the group that produced it and a huge creative force in the group, but he's almost unknown in the Unix community. He invented a couple of things you might have heard of: pipes and — get this — macros. Well, someone had to do it and that someone was Doug. As Ken once said when we were talking one day in the Unix room, "There's no one smarter than Doug."
** Rob Pike (2004). Slashdot: Rob Pike Responds
* McIlroy ... is the smartest of all of us and the least remembered or written down of all of us [programmers at Bell Labs' Computing Techniques Research Department].
** Ken Thompson (2019). VCF East 2019 – Brian Kernighan interviews Ken Thompson
* Doug McIlroy's influence on the development of both C and C++ cannot be overestimated. I cannot remember a single critical design decision in C++ that I have not discussed at length with Doug.
** Bjarne Stroustrup (1984). A History of C++: 1979−1991

## External links

* Doug McIlroy's homepage