annotate unix-phil.ms @ 10:355ed69a34a8

more about the shell and worse is better (ch03)
author meillo@marmaro.de
date Sat, 20 Feb 2010 12:14:01 +0100
parents 529168f49f29
children b32a43a62cae
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19 ..
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20 .ds [. \ [
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21 .ds .] ]
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22 .\"----------------------------------------
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23 .TL
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24 Why the Unix Philosophy still matters
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25 .AU
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26 markus schnalke <meillo@marmaro.de>
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27 .AB
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28 .ti \n(.iu
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29 This paper discusses the importance of the Unix Philosophy in software design.
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30 Today, few software designers are aware of these concepts,
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31 and thus most modern software is limited and does not make use of software leverage.
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32 Knowing and following the tenets of the Unix Philosophy makes software more valuable.
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33 .AE
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34
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35 .\".if t .2C
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38 .ps -1
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39 This paper was prepared for the seminar ``Software Analysis'' at University Ulm.
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40 Mentor was professor Schweiggert. 2010-02-05
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41 .br
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42 You may get this document from my website
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43 .CW \s-1http://marmaro.de/docs
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44 .FE
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45
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46 .NH 1
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47 Introduction
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48 .LP
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49 Building a software is a process from an idea of the purpose of the software
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50 to its release.
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51 No matter \fIhow\fP the process is run, two things are common:
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52 the initial idea and the release.
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53 The process in between can be of any shape.
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54 The the maintenance work after the release is ignored for the moment.
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55 .PP
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56 The process of building splits mainly in two parts:
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57 the planning of what and how to build, and implementing the plan by writing code.
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58 This paper focuses on the planning part \(en the designing of the software.
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59 .PP
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60 Software design is the plan of how the internals and externals of the software should look like,
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61 based on the requirements.
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62 This paper discusses the recommendations of the Unix Philosophy about software design.
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63 .PP
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64 The here discussed ideas can get applied by any development process.
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65 The Unix Philosophy does recommend how the software development process should look like,
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66 but this shall not be of matter here.
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67 Similar, the question of how to write the code is out of focus.
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68 .PP
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69 The name ``Unix Philosophy'' was already mentioned several times, but it was not explained yet.
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70 The Unix Philosophy is the essence of how the Unix operating system and its toolchest was designed.
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71 It is no limited set of rules, but what people see to be common to typical Unix software.
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72 Several people stated their view on the Unix Philosophy.
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73 Best known are:
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74 .IP \(bu
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75 Doug McIlroy's summary: ``Write programs that do one thing and do it well.''
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76 .[
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77 %A M. D. McIlroy
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78 %A E. N. Pinson
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79 %A B. A. Taque
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80 %T UNIX Time-Sharing System Forward
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81 %J The Bell System Technical Journal
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82 %D 1978
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83 %V 57
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84 %N 6
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85 %P 1902
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86 .]
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87 .IP \(bu
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88 Mike Gancarz' book ``The UNIX Philosophy''.
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89 .[
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90 %A Mike Gancarz
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91 %T The UNIX Philosophy
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92 %D 1995
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93 %I Digital Press
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94 .]
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95 .IP \(bu
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96 Eric S. Raymond's book ``The Art of UNIX Programming''.
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97 .[
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98 %A Eric S. Raymond
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99 %T The Art of UNIX Programming
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100 %D 2003
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101 %I Addison-Wesley
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102 %O .CW \s-1http://www.faqs.org/docs/artu/
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103 .]
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104 .LP
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105 These different views on the Unix Philosophy have much in common.
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106 Especially, the main concepts are similar for all of them.
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107 But there are also points on which they differ.
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108 This only underlines what the Unix Philosophy is:
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109 A retrospective view on the main concepts of Unix software;
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110 especially those that were successful and unique to Unix.
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111 .\" really?
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112 .PP
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113 Before we will have a look at concrete concepts,
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114 we discuss why software design is important
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115 and what problems bad design introduces.
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116
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117
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118 .NH 1
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119 Importance of software design in general
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120 .LP
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121 Why should we design software at all?
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122 It is general knowledge, that even a bad plan is better than no plan.
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123 Ignoring software design is programming without a plan.
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124 This will lead pretty sure to horrible results.
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125 .PP
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126 The design of a software is its internal and external shape.
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127 The design talked about here has nothing to do with visual appearance.
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128 If we see a program as a car, then its color is of no matter.
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129 Its design would be the car's size, its shape, the number and position of doors,
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130 the ratio of passenger and cargo transport, and so forth.
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131 .PP
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132 A software's design is about quality properties.
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133 Each of the cars may be able to drive from A to B,
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134 but it depends on its properties whether it is a good car for passenger transport or not.
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135 It also depends on its properties if it is a good choice for a rough mountain area.
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136 .PP
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137 Requirements to a software are twofold: functional and non-functional.
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138 Functional requirements are easier to define and to verify.
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139 They are directly the software's functions.
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140 Functional requirements are the reason why software gets written.
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141 Someone has a problem and needs a tool to solve it.
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142 Being able to solve the problem is the main functional requirement.
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143 It is the driving force behind all programming effort.
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144 .PP
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145 On the other hand, there are also non-functional requirements.
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146 They are called \fIquality\fP requirements, too.
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147 The quality of a software is about properties that are not directly related to
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148 the software's basic functions.
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149 Quality aspects are about the properties that are overlooked at first sight.
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150 .PP
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151 Quality is of few matter when the software gets initially built,
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152 but it will be of matter in usage and maintenance of the software.
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153 A short-sighted might see in developing a software mainly building something up.
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154 Reality shows, that building the software the first time is only a small amount
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155 of the overall work.
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156 Bug fixing, extending, rebuilding of parts \(en short: maintenance work \(en
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157 does soon take over the major part of the time spent on a software.
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158 Not to forget the usage of the software.
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159 These processes are highly influenced by the software's quality.
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160 Thus, quality should never be neglected.
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161 The problem is that you hardly ``stumble over'' bad quality during the first build,
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162 but this is the time when you should care about good quality most.
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163 .PP
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164 Software design is not about the basic function of a software;
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165 this requirement will get satisfied anyway, as it is the main driving force behind the development.
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166 Software design is about quality aspects of the software.
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167 Good design will lead to good quality, bad design to bad quality.
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168 The primary functions of the software will be affected modestly by bad quality,
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169 but good quality can provide a lot of additional gain from the software,
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170 even at places where one never expected it.
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171 .PP
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172 The ISO/IEC 9126-1 standard, part 1,
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173 .[
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174 %I International Organization for Standardization
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175 %T ISO Standard 9126: Software Engineering \(en Product Quality, part 1
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176 %C Geneve
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177 %D 2001
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178 .]
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179 defines the quality model as consisting out of:
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180 .IP \(bu
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181 .I Functionality
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182 (suitability, accuracy, inter\%operability, security)
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183 .IP \(bu
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184 .I Reliability
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185 (maturity, fault tolerance, recoverability)
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186 .IP \(bu
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187 .I Usability
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188 (understandability, learnability, operability, attractiveness)
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189 .IP \(bu
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190 .I Efficiency
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191 (time behavior, resource utilization)
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192 .IP \(bu
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193 .I Maintainability
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194 (analysability, changeability, stability, testability)
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195 .IP \(bu
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196 .I Portability
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197 (adaptability, installability, co-existence, replaceability)
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198 .LP
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199 These goals are parts of a software's design.
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200 Good design can give these properties to a software,
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201 bad designed software will miss them.
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202 .PP
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203 One further goal of software design is consistency.
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204 Consistency eases understanding, working on, and using things.
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205 Consistent internals and consistent interfaces to the outside can be provided by good design.
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206 .PP
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207 We should design software because good design avoids many problems during a software's lifetime.
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208 And we should design software because good design can offer much gain,
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209 that can be unrelated to the software main intend.
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210 Indeed, we should spend much effort into good design to make the software more valuable.
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211 The Unix Philosophy shows how to design software well.
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212 It offers guidelines to achieve good quality and high gain for the effort spent.
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213
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214
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215 .NH 1
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216 The Unix Philosophy
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217 .LP
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218 The origins of the Unix Philosophy were already introduced.
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219 This chapter explains the philosophy, oriented on Gancarz,
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220 and shows concrete examples of its application.
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221
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222 .SH
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223 Examples
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224 .LP
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225 Following are some examples to demonstrate how applied Unix Philosophy feels like.
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226 Knowledge of using the Unix shell is assumed.
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227 .PP
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228 Counting the number of files in the current directory:
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229 .DS I 2n
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230 .CW
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231 .ps -1
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232 ls | wc -l
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233 .DE
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234 The
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235 .CW ls
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236 command lists all files in the current directory, one per line,
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237 and
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238 .CW "wc -l
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239 counts the number of lines.
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240 .PP
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241 Counting the number of files that do not contain ``foo'' in their name:
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242 .DS I 2n
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243 .CW
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244 .ps -1
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245 ls | grep -v foo | wc -l
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246 .DE
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247 Here, the list of files is filtered by
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248 .CW grep
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249 to remove all that contain ``foo''.
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250 The rest is the same as in the previous example.
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251 .PP
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252 Finding the five largest entries in the current directory.
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253 .DS I 2n
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254 .CW
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255 .ps -1
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256 du -s * | sort -nr | sed 5q
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257 .DE
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258 .CW "du -s *
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259 returns the recursively summed sizes of all files
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260 \(en no matter if they are regular files or directories.
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261 .CW "sort -nr
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262 sorts the list numerically in reverse order.
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263 Finally,
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264 .CW "sed 5q
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265 quits after it has printed the fifth line.
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266 .PP
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267 The presented command lines are examples of what Unix people would use
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268 to get the desired output.
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269 There are also other ways to get the same output.
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270 It's a user's decision which way to go.
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271
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272 .SH
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273 Pipes
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274 .LP
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275 The examples show that many tasks on a Unix system
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276 are accomplished by combining several small programs.
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277 The connection between the single programs is denoted by the pipe operator `|'.
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278 .PP
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279 Pipes, and their extensive and easy use, are one of the great
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280 achievements of the Unix system.
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281 Pipes between programs have been possible in earlier operating systems,
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282 but it has never been a so central part of the concept.
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283 When, in the early seventies, Doug McIlroy introduced pipes for the
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284 Unix system,
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285 ``it was this concept and notation for linking several programs together
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286 that transformed Unix from a basic file-sharing system to an entirely new way of computing.''
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287 .[
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288 %T Unix: An Oral History
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289 %O .CW \s-1http://www.princeton.edu/~hos/frs122/unixhist/finalhis.htm
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290 .]
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291 .PP
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292 Being able to specify pipelines in an easy way is,
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293 however, not enough by itself.
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294 It is only one half.
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295 The other is the design of the programs that are used in the pipeline.
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296 They have to interfaces that allows them to be used in such a way.
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297
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298 .SH
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299 Interface architecture
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300 .LP
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301 Unix is, first of all, simple: Everything is a file.
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302 Files are sequences of bytes, without any special structure.
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303 Programs should be filters, which read a stream of bytes from ``standard input'' (stdin)
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304 and write a stream of bytes to ``standard output'' (stdout).
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305 .PP
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306 If the files \fIare\fP sequences of bytes,
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307 and the programs \fIare\fP filters on byte streams,
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308 then there is exactly one standardized interface.
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309 Thus it is possible to combine them in any desired way.
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310 .PP
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311 Even a handful of small programs will yield a large set of combinations,
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312 and thus a large set of different functions.
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313 This is leverage!
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314 If the programs are orthogonal to each other \(en the best case \(en
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315 then the set of different functions is greatest.
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316 .PP
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317 The Unix toolchest \fIis\fP a set of small programs that
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318 are filters on byte streams.
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319 They are, to a large extend, unrelated in their function.
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320 Hence, the Unix toolchest provides a large set of functions
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321 that can be accessed by combining the programs in the desired way.
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322
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323 .SH
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324 The toolchest approach
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325 .LP
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326 A toolchest is a set of tools.
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327 Instead of having one big tool for all tasks, one has many small tools,
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328 each for one task.
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329 Difficult tasks are solved by combining several of the small, simple tools.
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330 .PP
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331 It is easier and less error-prone to write small programs.
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332 It is also easier and less error-prone to write a large set of small programs,
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333 than to write one large program with all the functionality included.
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334 If the small programs are combinable, then they offer even a larger set
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335 of functions than the single large program.
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336 Hence, one gets two advantages out of writing small, combinable programs.
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337 .PP
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338 There are two drawbacks of the toolchest approach.
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339 First, one simple, standardized, unidirectional interface has to be sufficient.
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340 If one feels the need for more ``logic'' than a stream of bytes,
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341 then a different approach might be of need.
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342 But it is also possible, that he just can not imaging a design where
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343 a stream of bytes is sufficient.
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344 By becoming more familiar with the ``Unix style of thinking'',
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345 developers will more often and easier find simple designs where
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346 a stream of bytes is a sufficient interface.
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347 .PP
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348 The second drawback of a toolchest affects the users.
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349 A toolchest is often more difficult to use for novices.
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350 It is necessary to become familiar with each of the tools,
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351 to be able to use the right one in a given situation.
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352 Additionally, one needs to combine the tools in a senseful way on its own.
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353 This is like a sharp knife \(en it is a powerful tool in the hand of a master,
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354 but of no good value in the hand of an unskilled.
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355 .PP
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356 However, learning single, small tool of the toolchest is easier than
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357 learning a complex tool.
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358 The user will have a basic understanding of a yet unknown tool,
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359 if the several tools of the toolchest have a common style.
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360 He will be able to transfer knowledge over one tool to another.
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361 .PP
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362 Moreover, the second drawback can be removed easily by adding wrappers
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363 around the single tools.
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364 Novice users do not need to learn several tools if a professional wraps
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365 the single commands into a more high-level script.
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366 Note that the wrapper script still calls the small tools;
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367 the wrapper script is just like a skin around.
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368 No complexity is added this way,
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369 but new programs can get created out of existing one with very low effort.
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370 .PP
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371 A wrapper script for finding the five largest entries in the current directory
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372 could look like this:
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373 .DS I 2n
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374 .CW
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375 .ps -1
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376 #!/bin/sh
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377 du -s * | sort -nr | sed 5q
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378 .DE
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379 The script itself is just a text file that calls the command line
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380 a professional user would type in directly.
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381 Making the program flexible on the number of entries it prints,
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382 is easily possible:
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383 .DS I 2n
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384 .CW
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385 .ps -1
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386 #!/bin/sh
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387 num=5
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388 [ $# -eq 1 ] && num="$1"
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389 du -sh * | sort -nr | sed "${num}q"
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390 .DE
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391 This script acts like the one before, when called without an argument.
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392 But one can also specify a numerical argument to define the number of lines to print.
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393
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394 .SH
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395 A powerful shell
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396 .LP
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397 It was already said, that the Unix shell provides the possibility to
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398 combine small programs into large ones easily.
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399 A powerful shell is a great feature in other ways, too.
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400 .PP
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401 For instance by including a scripting language.
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402 The control statements are build into the shell.
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403 The functions, however, are the normal programs, everyone can use on the system.
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404 Thus, the programs are known, so learning to program in the shell is easy.
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405 Using normal programs as functions in the shell programming language
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406 is only possible because they are small and combinable tools in a toolchest style.
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407 .PP
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408 The Unix shell encourages to write small scripts out of other programs,
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409 because it is so easy to do.
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410 This is a great step towards automation.
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411 It is wonderful if the effort to automate a task equals the effort
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412 it takes to do it the second time by hand.
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413 If it is so, then the user will be happy to automate everything he does more than once.
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414 .PP
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415 Small programs that do one job well, standardized interfaces between them,
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416 a mechanism to combine parts to larger parts, and an easy way to automate tasks,
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417 this will inevitably produce software leverage.
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418 Getting multiple times the benefit of an investment is a great offer.
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419 .PP
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420 The shell also encourages rapid prototyping.
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421 Many well known programs started as quickly hacked shell scripts,
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422 and turned into ``real'' programs, written in C, later.
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423 Building a prototype first is a way to avoid the biggest problems
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424 in application development.
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425 Fred Brooks writes in ``No Silver Bullet'':
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426 .[
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427 %A Frederick P. Brooks, Jr.
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428 %T No Silver Bullet: Essence and Accidents of Software Engineering
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429 %B Information Processing 1986, the Proceedings of the IFIP Tenth World Computing Conference
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430 %E H.-J. Kugler
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431 %D 1986
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432 %P 1069\(en1076
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433 %I Elsevier Science B.V.
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434 %C Amsterdam, The Netherlands
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435 .]
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436 .QP
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437 The hardest single part of building a software system is deciding precisely what to build.
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438 No other part of the conceptual work is so difficult as establishing the detailed
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439 technical requirements, [...].
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440 No other part of the work so cripples the resulting system if done wrong.
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441 No other part is more difficult to rectify later.
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442 .PP
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443 Writing a prototype is a great method to become familiar with the requirements
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444 and to actually run into real problems.
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445 Today, prototyping is often seen as a first step in building a software.
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446 This is, of course, good.
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447 However, the Unix Philosophy has an \fIadditional\fP perspective on prototyping:
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448 After having built the prototype, one might notice, that the prototype is already
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449 \fIgood enough\fP.
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450 Hence, no reimplementation, in a more sophisticated programming language, might be of need,
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451 for the moment.
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452 Maybe later, it might be neccessary to rewrite the software, but not now.
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453 .PP
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454 By delaying further work, one keeps the flexibility to react easily on
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455 changing requirements.
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456 Software parts that are not written will not miss the requirements.
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457
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458 .SH
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459 Worse is better
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460 .LP
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461 The Unix Philosophy aims for the 80% solution;
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462 others call it the ``Worse is better'' approach.
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463 .PP
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464 First, practical experience shows, that it is almost never possible to define the
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465 requirements completely and correctly the first time.
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466 Hence one should not try to; it will fail anyway.
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467 Second, practical experience shows, that requirements change during time.
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468 Hence it is best to delay requirement-based design decisions as long as possible.
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469 Also, the software should be small and flexible as long as possible
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470 to react on changing requirements.
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471 Shell scripts, for example, are more easily adjusted as C programs.
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472 Third, practical experience shows, that maintenance is hard work.
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473 Hence, one should keep the amount of software as small as possible;
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474 it should just fulfill the \fIcurrent\fP requirements.
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475 Software parts that will be written later, do not need maintenance now.
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476 .PP
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477 Starting with a prototype in a scripting language has several advantages:
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478 .IP \(bu
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479 As the initial effort is low, one will likely start right away.
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480 .IP \(bu
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481 As working parts are available soon, the real requirements can get identified soon.
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482 .IP \(bu
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483 When a software is usable, it gets used, and thus tested.
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484 Hence problems will be found at early stages of the development.
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485 .IP \(bu
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486 The prototype might be enough for the moment,
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487 thus further work on the software can be delayed to a time
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488 when one knows better about the requirements and problems,
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489 than now.
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490 .IP \(bu
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491 Implementing now only the parts that are actually needed now,
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492 requires fewer maintenance work.
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493 .IP \(bu
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494 If the global situation changes so that the software is not needed anymore,
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diff changeset
495 then less effort was spent into the project, than it would have be
355ed69a34a8 more about the shell and worse is better (ch03)
meillo@marmaro.de
parents: 9
diff changeset
496 when a different approach had been used.
355ed69a34a8 more about the shell and worse is better (ch03)
meillo@marmaro.de
parents: 9
diff changeset
497
355ed69a34a8 more about the shell and worse is better (ch03)
meillo@marmaro.de
parents: 9
diff changeset
498
355ed69a34a8 more about the shell and worse is better (ch03)
meillo@marmaro.de
parents: 9
diff changeset
499
355ed69a34a8 more about the shell and worse is better (ch03)
meillo@marmaro.de
parents: 9
diff changeset
500
355ed69a34a8 more about the shell and worse is better (ch03)
meillo@marmaro.de
parents: 9
diff changeset
501
5
48f1f3465550 new content about interfaces and toolchests
meillo@marmaro.de
parents: 4
diff changeset
502
4
c707b0c5c849 new text about pipes
meillo@marmaro.de
parents: 3
diff changeset
503
c707b0c5c849 new text about pipes
meillo@marmaro.de
parents: 3
diff changeset
504
0
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
505
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
506
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
507 .NH 2
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
508 Results
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
509 .LP
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
510 The unix phil is an answer to the sw design question
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
511 .LP
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
512 tool chains empower the uses of sw
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
513
8
924b2ac2d477 new text about toolchest and shell (ch03)
meillo@marmaro.de
parents: 7
diff changeset
514
924b2ac2d477 new text about toolchest and shell (ch03)
meillo@marmaro.de
parents: 7
diff changeset
515
0
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
516 .NH 1
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
517 Case study: nmh
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
518
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
519 .NH 2
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
520 History
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
521 .LP
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
522 MH, nmh.
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
523 They are old.
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
524
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
525 .NH 2
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
526 Contrasts to similar sw
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
527 .LP
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
528 vs. Thunderbird, mutt, mailx, pine
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
529 .LP
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
530 flexibility, no redundancy, use the shell
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
531
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
532 .NH 2
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
533 Gains of the design
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
534 .LP
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
535
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
536 .NH 2
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
537 Problems
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
538 .LP
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
539
8
924b2ac2d477 new text about toolchest and shell (ch03)
meillo@marmaro.de
parents: 7
diff changeset
540
924b2ac2d477 new text about toolchest and shell (ch03)
meillo@marmaro.de
parents: 7
diff changeset
541
0
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
542 .NH 1
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
543 Case study: uzbl
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
544
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
545 .NH 2
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
546 History
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
547 .LP
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
548 uzbl is young
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
549
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
550 .NH 2
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
551 Contrasts to similar sw
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
552 .LP
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
553 like with nmh
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
554 .LP
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
555 addons, plugins, modules
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
556
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
557 .NH 2
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
558 Gains of the design
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
559 .LP
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
560
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
561 .NH 2
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
562 Problems
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
563 .LP
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
564 broken web
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
565
8
924b2ac2d477 new text about toolchest and shell (ch03)
meillo@marmaro.de
parents: 7
diff changeset
566
924b2ac2d477 new text about toolchest and shell (ch03)
meillo@marmaro.de
parents: 7
diff changeset
567
0
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
568 .NH 1
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
569 Final thoughts
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
570
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
571 .NH 2
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
572 Quick summary
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
573 .LP
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
574 good design
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
575 .LP
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
576 unix phil
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
577 .LP
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
578 case studies
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
579
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
580 .NH 2
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
581 Why people should choose
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
582 .LP
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
583 Make the right choice!
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
584
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
585 .nr PI .5i
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
586 .rm ]<
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
587 .de ]<
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
588 .LP
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
589 .de FP
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
590 .IP \\\\$1.
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
591 \\..
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
592 .rm FS FE
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
593 ..
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
594 .SH
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
595 References
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
596 .[
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
597 $LIST$
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
598 .]
cecef8bfa812 early version, mainly the outline
meillo@marmaro.de
parents:
diff changeset
599 .wh -1p