Table of Contents
Introduction vii
1 Have a Clear and Concise Purpose 1
1.1 Problem 1: Backing Up Data 2
1.2 Problem 2: Managing Tasks 5
1.3 What Makes an Awesome Command-Line App 10
1.4 Moving On 11
2 Be Easy to Use 13
2.1 Understanding the Command Line: Options, Arguments, and Commands 13
2.2 Building an Easy-to-Use Command-Line Interface 18
2.3 Building an Easy-to-Use Command-Suite Interface 23
2.4 Moving On 31
3 Be Helpful 33
3.1 Documenting a Command-Line Interface 33
3.2 Documenting a Command Suite 38
3.3 Including a Man Page 42
3.4 Writing Good Help Text and Documentation 47
3.5 Moving On 50
4 Play Well with Others 53
4.1 Using Exit Codes to Report Success or Failure 54
4.2 Using the Standard Output and Error Streams Appropriately 59
4.3 Formatting Output for Use as Input to Another Program 63
4.4 Trapping Signals Sent from Other Apps 68
4.5 Moving On 69
5 Delight Casual Users 71
5.1 Choosing Names for Options and Commands 72
5.2 Choosing Default Values for Flags and Arguments 76
5.3 Deciding Default Behavior 86
5.4 Moving On 86
6 Make Configuration Easy 89
6.1 Why External Configuration? 89
6.2 Reading External Configuration from Files 90
6.3 Using Configuration Files with Command Suites 94
6.4 Design Considerations When Using Configuration 98
6.5 Moving On 99
7 Distribute Painlessly 101
7.1 Distributing with RubyGems 101
7.2 Distributing Without RubyGems 108
7.3 Collaborating with Other Developers 109
7.4 Moving On 115
8 Test, Test, Test 117
8.1 Testing User Behavior with Acceptance Tests 118
8.2 Testing in Isolation with Unit Tests 131
8.3 A Word About Test-Driven Development 139
8.4 Moving On 139
9 Be Easy to Maintain 141
9.1 Dividing Code into Multiple Files 141
9.2 Designing Code for Maintainability 146
9.3 Moving On 151
10 Add Color, Formatting, and Interactivity 153
10.1 Adding Color Using ANSI Escape Sequences 154
10.2 Formatting Output with Tables 159
10.3 Providing Interactive User Input with readline 164
10.4 Moving On 173
Al Common Command-Line Gems and Libraries 175
A1.1 Alternatives for Simple Command-Line Apps 176
A1.2 Alternatives for Command Suites 184
A1.3 Other Relevant Libraries 189
A2 Bibliography 193
Index 195