Douglas McIlroy

Malcolm Douglas McIlroy (born 1932) is an American mathematician, engineer, and programmer. As of 2019 he is an Adjunct Professor of Computer Science at Dartmouth College.

McIlroy is best known for having originally proposed Unix pipelines and developed several Unix tools, such as echo, spell, diff, sort, join, graph, speak, and tr. and code reuse

He taught at MIT from 1954 to 1958.

McIlroy joined Bell Laboratories in 1958; from 1965 to 1986 was head of its Computing Techniques Research Department (the birthplace of the Unix operating system), and thereafter was Distinguished Member of Technical Staff. In 1959, together with Douglas E. Eastwood of Bell Labs, he introduced conditional and recursive macros into popular SAP assembler, creating what is known as Macro SAP. His 1960 paper was also seminal in the area of extending any (including high-level) programming languages through macro processors. McIlroy's macro processing ideas were also the main inspiration for TRAC macro processor.

He also coauthored M6 macro processor in FORTRAN IV, which was used in ALTRAN) and Unix operating systems (such as diff, echo, tr, join and look), versions of which are widespread to this day through adoption of the POSIX standard and Unix-like operating systems. He introduced the idea of Unix pipelines.

McIlroy also took over from Dennis Ritchie compilation of the Unix manual "as a labor of love". Particularly, he edited volume 1 of the manual pages for Version 7 Unix. According to Sandy Fraser: "The fact that there was a manual, that he [McIlroy] insisted on a high standard for the manual, meant that he insisted on a high standard for every one of the programs that was documented".

Computer language design

McIlroy influenced the design and implementation of SNOBOL programming language. His string manipulation macros were used extensively in the initial SNOBOL implementation of 1962, and figured prominently in subsequent work, eventually leading to its machine-independent implementation language SIL. The table type (associative array) was added to SNOBOL4 on McIlroy's insistence in 1969.

In 1960s, he participated in the design of PL/I programming language. He was a member of the IBM–SHARE committee that designed the language and, together with Robert Morris, wrote the Early PL/I (EPL) compiler in TMG for the Multics project.

Around 1965, McIlroy, together with W. Stanley Brown, implemented the original version of ALTRAN programming language for IBM 7094 computers.

Algorithms

In the 1990s, McIlroy worked on improving sorting techniques, particularly he co-authored an optimized qsort with Jon Bentley.

In 1969, he contributed an efficient algorithm to generate all spanning trees in a graph (first discovered by George J. Minty in 1965).

Awards and recognition

In 1995, he was elected as a Fellow of the American Association for the Advancement of Science. In 2004, he won both the USENIX Lifetime Achievement Award ("The Flame") and its Software Tools User Group (STUG) award. In 2006, he was elected as a member of the National Academy of Engineering.

Views on computing

McIlroy is attributed the quote "The real hero of programming is the one who writes negative code," where the meaning of negative code is taken to be similar to the famous Apple developer, Bill Atkinson, team anecdote (i.e., when a change in a program source makes the number of lines of code decrease ('negative' code), while its overall quality, readability or speed improves).

Literature

References

External links

;Bell Labs

archived homepage at Bell Labs
McIlroy's History of Unix speech (audio), includes many autobiographical notes, along with discussion of many of the major Unix authors

;cs.dartmouth.edu

Doug McIlroy's homepage
Biography
Publications by M. D. McIlroy
Doug McIlroy Facts

;Ancestry of Linux

Ancestry of Linux - How the Fun Began , presentation November 2005: (presentation) (audio) (video)

;code.google.com

Original unix spell source code, written by Doug McIlroy