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Bash Guide for Beginners
Table of Contents
Chapter 3. The Bash environment..................................................................................................................28
3.1. Shell initialization files...................................................................................................................28
3.1.1. System−wide configuration files...........................................................................................28
3.1.2. Individual user configuration files........................................................................................30
3.1.3. Changing shell configuration files........................................................................................32
3.2. Variables.........................................................................................................................................33
3.2.1. Types of variables.................................................................................................................33
3.2.2. Creating variables..................................................................................................................36
3.2.3. Exporting variables................................................................................................................37
3.2.4. Reserved variables.................................................................................................................38
3.2.5. Special parameters.................................................................................................................40
3.3. Quoting characters..........................................................................................................................42
3.3.1. Why?.....................................................................................................................................42
3.3.2. Escape characters..................................................................................................................42
3.3.3. Single quotes.........................................................................................................................43
3.3.4. Double quotes........................................................................................................................43
3.3.5. ANSI−C quoting...................................................................................................................44
3.3.6. Locales...................................................................................................................................44
3.4. Shell expansion...............................................................................................................................44
3.4.1. General..................................................................................................................................44
3.4.2. Brace expansion....................................................................................................................44
3.4.3. Tilde expansion.....................................................................................................................44
3.4.4. Shell parameter and variable expansion................................................................................45
3.4.5. Command substitution...........................................................................................................46
3.4.6. Arithmetic expansion............................................................................................................47
3.4.7. Process substitution...............................................................................................................48
3.4.8. Word splitting........................................................................................................................48
3.4.9. File name expansion..............................................................................................................49
3.5. Aliases.............................................................................................................................................49
3.5.1. What are aliases?...................................................................................................................49
3.5.2. Creating and removing aliases..............................................................................................50
3.6. More Bash options..........................................................................................................................51
3.6.1. Displaying options.................................................................................................................51
3.6.2. Changing options...................................................................................................................52
3.7. Summary.........................................................................................................................................53
3.8. Exercises.........................................................................................................................................53
Chapter 4. Regular expressions.......................................................................................................................55
4.1. Regular expressions........................................................................................................................55
4.1.1. What are regular expressions?...............................................................................................55
4.1.2. Regular expression metacharacters.......................................................................................55
4.1.3. Basic versus extended regular expressions...........................................................................56
4.2. Examples using grep.......................................................................................................................56
4.2.1. What is grep?.........................................................................................................................56
4.2.2. Grep and regular expressions................................................................................................57
4.3. Pattern matching using Bash features.............................................................................................59
4.3.1. Character ranges....................................................................................................................59
4.3.2. Character classes...................................................................................................................60
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