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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
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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

Conditional statements in Perl

Similar to the rest of the Perl language, we will have similarities with bash scripting and some completely new ways of implementing conditions. This will often work in our favor; thus, making the code more readable.

Replacing command line lists

First, we do not have the command line list logic, which we use in bash and we do not make use of the && and ||. Instead of these rather weird looking symbols, the conditional logic for single statements in Perl is written in the following manner:

exit(2) if scalar @ARGV < 1;
print("Hello $ARGV[0]\n") unless scalar @ARGV == 0;

In the first example, we exit with an error code of 2, if we have supplied less than one command-line argument. The bash equivalent to this will be:

[ $# -lt 1 ] && exit 2

In the second example, we will only print the hello statement if we have supplied arguments. This will be written in bash, as shown in the following example:

[ $# -eq 0 ] || echo "Hello $1"

Personally...

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