docs/unix-phil: unix-phil.ms comparison

comparison unix-phil.ms @ 47:b6ae4a8ab1d3

improved references and some minor design issues

author	meillo@marmaro.de
date	Mon, 12 Apr 2010 14:11:39 +0200
parents	98a1446744c7
children	40caeb9e9b25

comparison

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+.ps -1
+..
+.am DS
+.CW
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 .\"----------------------------------------
 .AE
 .FS
 .ps -1
 This paper was prepared for the ``Software Analysis'' seminar at University Ulm.
-Mentor was professor Schweiggert. 2010-04-05
+Mentor was professor Franz Schweiggert.
-.br
+Handed in on 2010-04-12.
 You may retrieve this document from
 .CW \s-1http://marmaro.de/docs \ .
 .FE
 .NH 1
 Introduction
 .XS
+.sp .5v
+.B
 \*(SN Introduction
 .XE
 .LP
 The Unix Philosophy is the essence of how the Unix operating system,
 especially its toolchest, was designed.
 .NH 1
 Importance of software design in general
 .XS
 .sp .5v
+.B
 \*(SN Importance of software design in general
 .XE
 .LP
 Software design is the planning of how the internal structure
 and external interfaces of a software should look like.
 .NH 1
 The Unix Philosophy
 .XS
 .sp .5v
+.B
 \*(SN The Unix Philosophy
 .XE
 .LP
 The origins of the Unix Philosophy were already introduced.
 This chapter explains the philosophy, oriented on Gancarz,
 Following are some examples to demonstrate how applied Unix Philosophy feels like.
 Knowledge of using the Unix shell is assumed.
 .PP
 Counting the number of files in the current directory:
 .DS
-.CW
-.ps -1
 ls | wc -l
 .DE
 The
 .CW ls
 command lists all files in the current directory, one per line,
 .CW "wc -l
 counts the number of lines.
 .PP
 Counting the number of files that do not contain ``foo'' in their name:
 .DS
-.CW
-.ps -1
 ls | grep -v foo | wc -l
 .DE
 Here, the list of files is filtered by
 .CW grep
 to remove all lines that contain ``foo''.
 The rest equals the previous example.
 .PP
 Finding the five largest entries in the current directory.
 .DS
-.CW
-.ps -1
 du -s * | sort -nr | sed 5q
 .DE
 .CW "du -s *
 returns the recursively summed sizes of all files in the current directory
 \(en no matter if they are regular files or directories.
 But new programs can get created out of existing one with very low effort.
 .PP
 A wrapper script for finding the five largest entries in the current directory
 could look like this:
 .DS
-.CW
-.ps -1
 #!/bin/sh
 du -s * | sort -nr | sed 5q
 .DE
 The script itself is just a text file that calls the command line,
 which a professional user would type in directly.
 It is probably worth to make the program flexible on the number of
 entries it prints:
 .DS
-.CW
-.ps -1
 #!/bin/sh
 num=5
 [ $# -eq 1 ] && num="$1"
 du -sh * | sort -nr | sed "${num}q"
 .DE
 No other part of the work so cripples the resulting system if done wrong.
 No other part is more difficult to rectify later.
 .PP
 Writing a prototype is a great method for becoming familiar with the requirements
 and to run into real problems early.
+.[ [
+gancarz
+unix philosophy
+.], page 28 f.]
 .PP
 Prototyping is often seen as a first step in building a software.
 This is, of course, good.
 However, the Unix Philosophy has an \fIadditional\fP perspective on prototyping:
 After having built the prototype, one might notice, that the prototype is already
 	\*(SN Worse is better
 .XE
 .LP
 The Unix Philosophy aims for the 90% solution;
 others call it the ``Worse is better'' approach.
-Practical experience shows, that:
+Experience from real life projects shows:
 .PP
 (1) It is almost never possible to define the
 requirements completely and correctly the first time.
 Hence one should not try to; one will fail anyway.
 .PP
 (3) Maintenance work is hard work.
 Hence, one should keep the amount of code as small as possible;
 it should just fulfill the \fIcurrent\fP requirements.
 Software parts that will be written in future,
 do not need maintenance till then.
+.PP
+See Brooks' ``The Mythical Man-Month'' for reference.
+.[ [
+brooks
+mythical man-month
+.], page 115 ff.]
 .PP
 Starting with a prototype in a scripting language has several advantages:
 .IP \(bu
 As the initial effort is low, one will likely start right away.
 .IP \(bu
 Transferred to software: The most successful software, is the fittest,
 is the one that survives.
 (This may be at the level of one creature, or at the level of one species.)
 The fitness of software is affected mainly by four properties:
 portability of code, portability of data, range of usability, and reusability of parts.
-.\" .IP \(bu
-.\" portability of code
-.\" .IP \(bu
-.\" portability of data
-.\" .IP \(bu
-.\" range of usability
-.\" .IP \(bu
-.\" reuseability of parts
 .PP
 (1)
 .I "Portability of code
 means, using high-level programming languages,
 sticking to the standard,
+.[ [
+kernighan pike
+practice of programming
+.], chapter\|8]
 and avoiding optimizations that introduce dependencies on specific hardware.
 Hardware has a much lower lifetime than software.
 By chaining software to a specific hardware,
 the software's lifetime gets shortened to that of this hardware.
 In contrast, software should be easy to port \(en
 adaptation is the key to success.
-.\" cf. practice of prog: ch08
 .PP
 (2)
 .I "Portability of data
 is best achieved by avoiding binary representations
 to store data, because binary representations differ from machine to machine.
 Important is that it is a plain text representation in a
 very common charset encoding.
 Apart from being able to transfer data between machines,
 readable data has the great advantage, that humans are able to directly
 read and edit it with text editors and other tools from the Unix toolchest.
-.\" gancarz tenet 5
+.[ [
+gancarz
+unix philosophy
+.], page 56 ff.]
 .PP
 (3)
 A large
 .I "range of usability
 ensures good adaptation, and thus good survival.
 .NH 1
 Case study: \s-1MH\s0
 .XS
 .sp .5v
+.B
 \*(SN Case study: \s-1MH\s0
 .XE
 .LP
 The previous chapter introduced and explained the Unix Philosophy
 from a general point of view.
 the driving force in the discussion.
 .PP
 This first case study is about the mail user agents (\s-1MUA\s0)
 \s-1MH\s0 (``mail handler'') and its descendent \fInmh\fP
 (``new mail handler'').
+.[
+nmh website
+.]
 \s-1MUA\s0s provide functions to read, compose, and organize mail,
 but (ideally) not to transfer it.
 In this document, the name \s-1MH\s0 will be used to include nmh.
 A distinction will only be made if differences between
 \s-1MH\s0 and nmh are described.
 It is possible to take one of the distributed format files
 or to write one yourself.
 To use the format as default for \f(CWscan\fP, a single line,
 reading
 .DS
-.CW
 scan: -form FORMATFILE
 .DE
 must be added to \f(CW.mh_profile\fP.
 If one wants this different format as an additional command,
 instead of changing the default, he needs to create a link to
 .NH 1
 Case study: uzbl
 .XS
 .sp .5v
+.B
 \*(SN Case study: uzbl
 .XE
 .LP
 The last chapter took a look on the \s-1MUA\s0 \s-1MH\s0,
 which is an old and established software.
 ``Maybe, if I find the time ;-)''.
 .PP
 Fortunately, he found the time.
 One day later, the first prototype was out.
 One week later, uzbl had an own website.
+.[
+uzbl website
+.]
 One month after the first code showed up,
-a mailing list was installed to coordinate and discuss further development.
+a mailing list was installed to coordinate and discuss further development,
-Then a wiki followed to store documentation and scripts that showed up on the
+and a wiki was added to store documentation and scripts that showed up on the
 mailing list and elsewhere.
 .PP
 In the, now, one year of uzbl's existence, it was heavily developed on various branches.
 Plaetinck's task became more and more to only merge the best code from the
 different branches into his main branch, and to apply patches.
+.[
+lwn uzbl
+.]
 About once a month, Plaetinck released a new version.
 In September 2009, he presented several forks of uzbl.
+.[ [
+uzbl website
+.], news archive]
 Uzbl, actually, opened the field for a whole family of web browsers with similar shape.
 .PP
 In July 2009, \fILinux Weekly News\fP published an interview with Plaetinck about uzbl.
+.[
+lwn uzbl
+.]
 In September 2009, the uzbl web browser was on \fISlashdot\fP.
+.[
+slashdot uzbl
+.]
 .NH 2
 Contrasts to other web browsers
 .XS
 	\*(SN Contrasts to other web browsers
 various tools that cover single jobs.
 Therefore, uzbl listens for commands on a named pipe (fifo), a Unix socket,
 and on stdin, and it writes events to a Unix socket and to stdout.
 Loading a webpage in a running uzbl instance requires only:
 .DS
-.CW
 echo 'uri http://example.org' >/path/to/uzbl-fifo
 .DE
 The graphical rendering of the webpage is done by webkit,
 a web content engine.
 Uzbl-core is built around libwebkit.
 The history mechanism of uzbl shall be presented as an example.
 Uzbl is configured to spawn a script to append an entry to the history
 whenever the event of a fully loaded page occurs.
 The script to append the entry to the history is not much more than:
 .DS
-.CW
 #!/bin/sh
 file=/path/to/uzbl-history
 echo `date +'%Y-%m-%d %H:%M:%S'`" $6 $7" >> $file
 .DE
 \f(CW$6\fP and \f(CW$7\fP expand to the \s-1URL\s0 and the page title.
 then displays \fIdmenu\fP to let the user select an item,
 and afterwards writes the selected \s-1URL\s0 into uzbl's command input pipe.
 With error checking and corner case handling removed,
 the script looks like this:
 .DS
-.CW
 #!/bin/sh
 file=/path/to/uzbl-history
 goto=`tac $file | dmenu | cut -d' ' -f 3`
 echo "uri $goto" > $4
 .DE
 .NH 1
 Final thoughts
 .XS
 .sp .5v
+.B
 \*(SN Final thoughts
 .XE
 .NH 2
 Quick summary
 	\*(SN Why people should choose
 .XE
 .LP
 Make the right choice!
-.nr PI .3i
+.bp
+.TL
+References
+.LP
+.XS
+.sp .5v
+.B
+References
+.XE
+.ev r
 .rm ]<
 .de ]<
 .LP
 .de FP
 .IP \\\\$1.
 \\..
 .rm FS FE
 ..
-.ds CH "
-.bp
-.rs
-.sp .3i
-.TL
-References
-.LP
-.XS
-.sp .5v
-References
-.XE
-.sp 2v
 .nr PS -1
 .nr VS -1
 .[
 $LIST$
 .]
-.\".wh -1p
+.nr PS +1
+.nr VS +1
+.ev
 .bp
-.PX
+.TL
+Table of Contents
+.LP
+.PX no

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