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 Linux Groups

User accounts are great for controlling security for individual users, but they aren't so good at allowing groups of users to share resources. To accomplish this, the Linux system uses another security concept, called groups.

Group permissions allow multiple users to share a common set of permissions for an object on the system, such as a file, directory, or device (more on that later in the “Decoding File Permissions” section).

Linux distributions differ somewhat on how they handle default group memberships. Some Linux distributions create just one group that contains all the user accounts as members. You need to be careful if your Linux distribution does this, because your files may be readable by all other users on the system. Other distributions create a separate group account for each user to provide a little more security.

Each group has a unique GID, which, like UIDs, is a unique numerical value on the system. Along with the GID, each group...