Bash Script

Scripts are files that contain shell commands which may be short or can be very complex. Scripts just make it easier because you can invoke one command to run all of the commands in the script.  Here instead of using 8 separate commands you can use one command to execute all of them.

This course is in 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

This course will help you start to actually write your own Bash Shell scripts by providing some basic examples and explanations of how they work.


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 Scripting and a basis for the courses that will follow.

Course Outline
Bash Scripts
Script Anatomy
Variables
Back Tics
Wildcards
Exit Codes
Functions
Positional Parameters
Testing
Flow Control
For Loop
While Loop
Case Statement
Conditions
Quiz

Lesson 2

t1.sh


#!/bin/sh
cd /etc
echo "################################"
echo "All configuration files"
ls *.conf
echo "################################"
echo "Files changed in last 3 days"
find /etc -iname '*.conf' -mtime -3
exit


If you create a shell script it may be run by typing:

source scriptname

or

You need to modify the script so it has the ability to execute by using chmod:

chmod 755 scriptname

or

chmod +x scriptname

Without making this modification the script will deny you access to execute the command.

When you use the source command the script executes as if the command were in your login session. However, if you use the name only to execute the command if will run a copy of the shell as a subprocess which runs the command, terminates and then returns the control back to the parent shell.