LPI Linux Certification in a Nutshell, 2nd Edition

Objective 1: Customize and Use the Shell Environment

This Objective could be considered a brief "getting started with shells" overview because it details many of the basic concepts necessary to utilize the shell environment on Linux. These concepts are fundamental and very important for system administrators working on Linux and Unix systems. If you're new to shells and shell scripting, take heart. You can think of it as a combination of computer interaction (conversation) and computer programming (automation). It is nothing more than that, but the result is far more than this simplicity implies. If you're an old hand with shell programming, you may want to skip ahead to brush up on some of the particulars necessary for Exam 102.

An Overview of Shells

A shell is a fundamental and important part of your Linux computing environment. Shells are user programs not unlike other text-based programs and utilities. They offer a rich customizable interface to your system. Some of the main items provided by your shell are:

An interactive textual user interface to the operating system

In this role, the shell is a command interpreter and display portal to the system. It offers you a communications channel to the kernel and is often thought of as the "shell around the kernel." That's where the name shell originates and is a good metaphor for conceptualizing how shells fit into the overall Linux picture.

An operating environment

Shells set up an environment for the execution of other programs, which ...