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Mastering Linux Shell Scripting

You're reading from   Mastering Linux Shell Scripting Master the complexities of Bash shell scripting and unlock the power of shell for your enterprise

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Product type Paperback
Published in Dec 2015
Publisher
ISBN-13 9781784396978
Length 198 pages
Edition 1st Edition
Tools
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Author (1):
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Andrew Mallett Andrew Mallett
Author Profile Icon Andrew Mallett
Andrew Mallett
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Table of Contents (16) Chapters Close

Preface 1. What and Why of Scripting with Bash FREE CHAPTER 2. Creating Interactive Scripts 3. Conditions Attached 4. Creating Code Snippets 5. Alternative Syntax 6. Iterating with Loops 7. Creating Building Blocks with Functions 8. Introducing sed 9. Automating Apache Virtual Hosts 10. Awk Fundamentals 11. Summarizing Logs with Awk 12. A Better lastlog with Awk 13. Using Perl as a Bash Scripting Alternative 14. Using Python as a Bash Scripting Alternative Index

Significant whitespace

A major difference between Python and most other languages is that additional whitespace can mean something. The indent level of your code defines the block of code to which it belongs. So far, we have not indented the code we have created past the start of the line. This means that all of the code is at the same indent level and belongs to the same code block. Rather than using brace brackets or do and done keywords to define the code block, we use indents. If we indent with four spaces, then we must stick to those four spaces. When we return to the previous indent level, we return to the previous code block.

This seems complex but it is really quite simple and keeps your code clean and uncluttered. If we edit the arg.py file to prevent unwelcomed errors, if an argument is not supplied, we can see this in action:

#!/usr/bin/python3
import sys
count = len(sys.argv)
if ( count > 1 ):
    print("Arguments supplied: " + str(count))
    print("Hello &quot...
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