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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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Toc

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

Displaying the highest ranking IP address

You should now realize some powers of awk and how immense the language structure is in itself. The data we have been able to produce from the 30K line file is truly powerful and easily extracted. We just need to replace the field we have used before with $1. This field represents the client IP address. If we make use of the following code, we will be able to print each IP Address and also the number of times it has been used to access the web server:

{ ip[$1]++ }
END {
for (i in ip)
print i, " has accessed the server ", ip[i], " times." }

We want to be able to extend this to show only the highest ranking of IP address, the address that has been used the most to access the site. The work, again, will mainly be in the END block and will make use of a comparison against the current highest ranking address. The following file can be created and saved as ip.awk:

{ ip[$1]++ }
END {
for (i in ip)
    if ( max < ip[i] ) {
        max...
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