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Mastering Linux Shell Scripting

You're reading from   Mastering Linux Shell Scripting A practical guide to Linux command-line, Bash scripting, and Shell programming

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Product type Paperback
Published in Apr 2018
Publisher
ISBN-13 9781788990554
Length 284 pages
Edition 2nd Edition
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Authors (2):
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Mokhtar Ebrahim Mokhtar Ebrahim
Author Profile Icon Mokhtar Ebrahim
Mokhtar Ebrahim
Andrew Mallett Andrew Mallett
Author Profile Icon Andrew Mallett
Andrew Mallett
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Table of Contents (17) Chapters Close

Preface 1. The 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 the Stream Editor 9. Automating Apache Virtual Hosts 10. AWK Fundamentals 11. Regular Expressions 12. Summarizing Logs with AWK 13. A Better lastlog with AWK 14. Using Python as a Bash Scripting Alternative 15. Assessments 16. Other Books You May Enjoy

Passing parameters to functions

Earlier within this chapter, we referred to functions as scripts within scripts and we will still maintain that analogy. Similar to how a script can have input parameters, we can create functions that also accept parameters that can make their operation less static. Before we work on a script, we can look at a useful function in the command line.

One of my pet peeves is overcommented configuration files, especially where documentation exists to detail the options available.

The GNU's Not Unix (GNU) Linux sed command can easily edit the file for us and remove commented lines and empty lines. We are introducing the stream editor, sed, here but we will look at it in more detail in the following chapter.

The sed command line that runs the in-place edit will be as follows:

$ sed -i.bak '/^\s*#/d;/^$/d' <filename>  

We can run out...

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