Linux Commands - Shells

This course is a series of mini-courses to help you with Bash Shell Scripting.  It is divided into several sections as you can see below.  In addition, to help you in the challenge of learning bash shell scripting you will find a quiz at the end of each mini-course.

Bash Shell: Basics
Bash Shell: vi Text Editor

Bash Shell: Nano Text Editor
Bash Shell: Scripting Basics
Bash Shell: Regular Expressions
Bash Shell: Text Filters

The first course will help you understand some of the concepts that are important to starting with the Bash Shell.  

Lesson 2

Course Difficulty
The course level is for the inexperienced Linux User / Administrator.  The focus is to provide a foundation for starting with the Bash Shell and a basis for the courses that will follow.

What is a shell?
A shell is a program that acts as an intermediary between the user and the Linux kernel.  The shell receives commands from the user through typed words and passes them into the kernel for processing.  The kernel has the ability to communicate with hardware and gather resources like files and memory.  The most common shell is bash.

History of Shells
The first shell was created by Steven Bourne in 1974 and was a part of UNIX version 7.  C shell was developed as an alternative by Bill Joy of the University of California at Berkley.  This shell was  part of the Berkley Software Foundation Distribution (BSD), which is still popular today.  The C shell functions much like C programming so users who have a background in C tend to gravitate in this direction.  The Korn shell is based on a combination of the Bourne and C shells. Each of these shells have advantages and are popular in use.

The GNU project created a completely free shell called the Bash shell.  It received the name from Bourne Again shell since it was based on the Bourne shell.  The bash shell was written originally by Brian Fox in 1988.  Bash has become the standard shell for Linux and is the default of most Linux distributions.

You can access the shell from a terminal.  Open a terminal and type:
echo $SHELL

This should show you which shell you are using, like so.

What the Bash Shell Does: (Outline for the Course) Quiz
The first section of the course is divided by what the shell does and how that impacts the user and writing scripts.
Free Webinar to Help Understand Bash Shell Basics

1. Interprets Commands
When you type a command in the shell it interprets the command and then executes it.
Interprets Commands

Command Line

Background Jobs

Escaping and Quoting

Command Line Scan

2. Provides Pipelines
The shell will allow users to set up pipes since it knows how to use them.

3. Allows I/O Redirection
The shell will enable redirection for input, output and error control.
I/O Redirection

2. Sets Variables
The shell gives you the option to set variables for PATH, HISTORY, etc.

Set Variables

5. Provides Customized Environment
Users are able to customize their environment because the shell provides the tools to do so.

Modify Prompt


Shell Options

Working Directory

File System


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