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)
Part I: The Linux Command Line
Part II: Shell Scripting Basics
Part III: Advanced Shell Scripting
Part IV: Creating Practical Scripts
End User License Agreement

Using Temporary Files

The Linux system contains a special directory location reserved for temporary files. Linux uses the /tmp directory for files that don't need to be kept indefinitely. Most Linux distributions configure the system to automatically remove any files in the /tmp directory at bootup.

Any user account on the system has privileges to read and write files in the /tmp directory. This feature provides an easy way for you to create temporary files that you don't necessarily have to worry about cleaning up.

There's even a specific command to use for creating a temporary file. The mktemp command allows you to easily create a unique temporary file in the /tmp folder. The shell creates the file but doesn't use your default umask value (see Chapter 7). Instead, it only assigns read and write permissions to the file's owner and makes you the owner of the file. After you create the file, you have full access to read and write to and from it from your script...