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Seminar ``Software Analysis''
.TL
\fR\s-6Why\s0\fP
.br
the Unix Philosophy
.br
.vs -4
\fR\s-6still matters\s0\fP
.AU
.ft R
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.ps 11
markus schnalke <meillo@marmaro.de>



.S "Software design
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\&... is about quality
.I
Good design \(-> good quality
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Bad design \(-> problems
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\&... and consistency
.LP
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Unix Phil = guidelines for good design



.S "Unix Phil and Software dev processes
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The Unix Phil:
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mostly *what*
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Software dev processes:
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mostly *how*
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Extreme Programming and the Unix Phil
are good friends



.S "The Unix Phil *itself*
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Wikipedia:
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The Unix philosophy is
a set of cultural norms and philosophical approaches
to developing software
based on the experience
of leading developers of the Unix operating system.
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.S Motivation
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Write the best possible programs for yourself
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Avoid \fBcomplexity\fP first and foremost!
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Exploit software \fBleverage\fP!



.S "The Unix Phil by Doug McIlroy (1978)
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This is the Unix philosophy:
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Write programs that do one thing and do it well.
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Write programs to work together.
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Write programs to handle text streams, because that is a universal interface.



.S "The Unix Phil by Mike Gancarz (1995)
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Small is beautiful.
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Make each program do one thing well.
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Build a prototype as soon as possible.
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Choose portability over efficiency.
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Store data in flat text files.
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Use software leverage to your advantage.
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Use shell scripts to increase leverage and portability.
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Avoid captive user interfaces.
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Make every program a filter.
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Plus ten lesser tenets



.S "Case studies
.LP
.B "MH / nmh
.LP
The only MUA that is a toolchest
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Makes use of the powerful shell
.LP
Great example of applied Unix Phil
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.B uzbl
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A web browser that adheres to the Unix Phil
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Central question:
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What is the one thing a web browser should do well?
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Makes very visible use of software leverage



.S "Why?
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We don't need just any solutions, we need good ones
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\fBComplexity\fP is the ``boss enemy'' of software developers
.LP
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\fBLeverage\fP is the largest unique benefit of software



.S "Further reading
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The paper to the slides
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My talk on this topic at the ChaosSeminar of CCC Ulm
.CW \s-2http://ulm.ccc.de/ChaosSeminar/2010/03_UnixPhil\s0
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Mike Gancarz' book
\fI``The Unix Philosophy''\fP
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\fI``cat -v Considered Harmful''\fP
by Pike and Kernighan
.CW \s-2http://harmful.cat-v.org/cat-v/\s+2



.S Colophon
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The paper and slides were prepared with:
.br
.CW "vi sed awk refer troff dpost spell make hg
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Most of the tools are from
.CW \s-2http://heirloom.sf.net\s0
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The `slides' macros are based on
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.CW \s-2http://repo.cat-v.org/troff-slider/\s0
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The paper, the slides, and the complete sources are available on my website
.CW \s-2http://marmaro.de/docs\s+2
.sp 3
2010-04-16