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Linux Shell Scripting Essentials

Linux Shell Scripting Essentials

By : Sinny Kumari
4.5 (2)
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Linux Shell Scripting Essentials

Linux Shell Scripting Essentials

4.5 (2)
By: Sinny Kumari

Overview of this book

Shell scripting is a quick method to prototype complex applications or problems. Shell scripts are a collection of commands to automate tasks, usually those for which the user has a repeated need, when working on Linux-based systems. Using simple commands or a combination of them in a shell can solve complex problems easily. This book starts with the basics, including essential commands that can be executed on Linux systems to perform tasks within a few nanoseconds. You’ll learn to use outputs from commands and transform them to show the data you require. Discover how to write shell scripts easily, execute script files, debug, and handle errors. Next, you’ll explore environment variables in shell programming and learn how to customize them and add a new environment. Finally, the book walks you through processes and how these interact with your shell scripts, along with how to use scripts to automate tasks and how to embed other languages and execute them.
Table of Contents (10 chapters)
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9
Index

Comparing files


A comparison between two similar files makes sense in order to know what differences exist between the two files. For example, comparing the results obtained by a command ran on two sets of data. Another example can be comparing an older and a newer version of a shell script file in order to know what modifications have been made in script. Shell provides the diff command for file comparison.

Files comparison using diff

The diff command is used to compare files line by line. The syntax of using the diff command is as follows:

diff [option] file1 file2

Where, file1 and file2 are the files to be compared.

The options of the diff command are explained in the following table:

Option

Description

-q

Only print if files differ

-s

Print a message on stdout if the two files are identical

-y

Display the diff results side by side

-i

Do case-insensitive comparison of the files' content

-b

Ignore changes in the number of whitespace

-u NUM

Output NUM (default 3)...

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