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

Handling Files

The shell provides many file manipulation commands on the Linux filesystem. This section walks you through the basic shell commands you need to handle files.

Creating files

Every once in a while you run into a situation where you need to create an empty file. For example, sometimes applications expect a log file to be present before they can write to it. In these situations, you can use the touch command to easily create an empty file:

$ touch test_one
$ ls -l test_one
-rw-rw-r-- 1 christine christine 0 May 21 14:17 test_one
$

The touch command creates the new file you specify and assigns your username as the file owner. Notice in the preceding example that the file size is zero because the touch command just created an empty file.

The touch command can also be used to change the modification time. This is done without changing the file contents:

$ ls -l test_one
-rw-rw-r-- 1 christine christine 0 May 21 14:17 test_one
$ touch test_one
$ ls -l test_one
-rw-rw-r-- 1 christine...