Book Image

Learning Linux Shell Scripting - Second Edition

By : Ganesh Sanjiv Naik
Book Image

Learning Linux Shell Scripting - Second Edition

By: Ganesh Sanjiv Naik

Overview of this book

Linux is the most powerful and universally adopted OS. Shell is a program that gives the user direct interaction with the operating system. Scripts are collections of commands that are stored in a file. The shell reads this file and acts on commands as if they were typed on the keyboard. Learning Linux Shell Scripting covers Bash, GNU Bourne Again Shell, preparing you to work in the exciting world of Linux shell scripting. CentOS is a popular rpm-based stable and secured Linux distribution. Therefore, we have used CentOS distribution instead of Ubuntu distribution. Linux Shell Scripting is independent of Linux distributions, but we have covered both types of distros. We start with an introduction to the Shell environment and basic commands used. Next, we explore process management in Linux OS, real-world essentials such as debugging and perform Shell arithmetic fluently. You'll then take a step ahead and learn new and advanced topics in Shell scripting, such as decision making, starting up a system, and customizing a Linux environment. You will also learn about grep, stream editor, and AWK, which are very powerful text filters and editors. Finally, you'll get to grips with taking backup, using other language scripts in Shell Scripts as well as automating database administration tasks for MySQL and Oracle. By the end of this book, you will be able to confidently use your own shell scripts in the real world.
Table of Contents (17 chapters)

Learning basic Linux commands

The following table lists a few basic Linux commands:

Command

Description

$ ls

This command is used to check the content of the directory.

$ pwd

This command is used to check the present working directory.

$ mkdir work

We will work in a separate directory called work in our home directory. Use this command to create a new directory called work in the current folder.

$ cd work

This command will change our working directory to the newly created work directory.

$ pwd

This command can be used to verify whether we moved to the expected directory.

$ touch hello.sh

This command is used to create a new empty file called hello.sh in the current folder.

$ cp hello.sh bye.sh

This command is used to copy one file into another file.

This will copy hello.sh as bye.sh.

$ mv bye.sh welcome.sh

This command is used to rename a file. This will rename bye.sh as welcome.sh.

$ ll

This command will display detailed information about files.

$ mv welcome.sh .welcome.sh

$ ls

Let's see some magic. Rename the file using the mv command and run the ls command.

Now, the ls command will not display our file .welcome.sh. The file is hidden. Any file or directory name starting with . (dot) becomes hidden.

$ ls -a

This command is used to display hidden files.

$ rm .welcolme.sh

This command is used to delete the file.

If we delete any file from the GUI, such as the GUI, then it will be moved to the /home/user/.local/share/Trash/files/ all deleted files folder.