Book Image

Linux Command Line and Shell Scripting Bible - Third Edition

By : Richard Blum, Christine Bresnahan
Book Image

Linux Command Line and Shell Scripting Bible - Third Edition

By: Richard Blum, Christine Bresnahan

Overview of this book

The Linux command line enables you to type specific shell commands directly into the system to manipulate files and query system resources. Command line statements can be combined into short programs called shell scripts, a practice increasing in popularity due to its usefulness in automation. Linux is a robust system with tremendous potential, and Linux Command Line and Shell Scripting Bible opens the door to new possibilities. Linux Command Line and Shell Scripting Bible is your essential Linux guide. It contains new functional examples that are fully updated to align with the latest Linux features. Beginning with command line fundamentals, the book moves into shell scripting and shows you the practical application of commands in automating frequently performed functions. This book is a complete guide providing detailed instruction and expert advice working within this aspect of Linux. Whether used as a tutorial or as a quick reference, this book contains information that every Linux user should know.
Table of Contents (34 chapters)
2
Part I: The Linux Command Line
13
Part II: Shell Scripting Basics
20
Part III: Advanced Shell Scripting
28
Part IV: Creating Practical Scripts
32
End User License Agreement

Summary

If you manipulate data files in shell scripts, you need to become familiar with regular expressions. Regular expressions are implemented in Linux utilities, programming languages, and applications using regular expression engines. A host of different regular expression engines is available in the Linux world. The two most popular are the POSIX Basic Regular Expression (BRE) engine and the POSIX Extended Regular Expression (ERE) engine. The sed editor conforms mainly to the BRE engine, while the gawk program utilizes most features found in the ERE engine.

A regular expression defines a pattern template that's used to filter text in a data stream. The pattern consists of a combination of standard text characters and special characters. The special characters are used by the regular expression engine to match a series of one or more characters, similarly to how wildcard characters work in other applications.

By combining characters and special characters, you can define a pattern...