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Learning Linux Shell Scripting

Learning Linux Shell Scripting - Second Edition

By : Ganesh Sanjiv Naik
3 (6)
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Learning Linux Shell Scripting

Learning Linux Shell Scripting

3 (6)
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)
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Using the trap command

If a signal or software interrupt is generated while the script is running, then we can define what action is performed by that interrupt handler using the trap command. The trap command helps us in re-assigning the system response to a particular signal through the user-defined function or commands.

The syntax to use the trap command is either of the following:

    $ trap 'command; command' signal-name
    $ trap 'command; command' signal-number

The usage as per the preceding syntax is as follows:

    trap 'echo "You pressed Control key" '  0 1 2 15

This will print the message You pressed Control key, when any of the signals SIGINT, SIGHUP, or SIGTERM are received by the process:

    trap 'rm file.tmp; echo "file.tmp is deleted" ' INT TERM HUP

When any of the SIGINT, SIGTERM, or SIGHUP signals...

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Learning Linux Shell Scripting
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