Book Image

Mastering Linux Shell Scripting

By : Andrew Mallett
Book Image

Mastering Linux Shell Scripting

By: Andrew Mallett

Overview of this book

Shell scripting is a quick method to prototype a complex application or a problem by automating tasks when working on Linux-based systems. Using both simple one-line commands and command sequences complex problems can be solved with ease, from text processing to backing up sysadmin tools. In this book, you’ll discover everything you need to know to master shell scripting and make informed choices about the elements you employ. Get to grips with the fundamentals of creating and running a script in normal mode, and in debug mode. Learn about various conditional statements' code snippets, and realize the power of repetition and loops in your shell script. Implement functions and edit files using the Stream Editor, script in Perl, program in Python – as well as complete coverage of other scripting languages to ensure you can choose the best tool for your project.
Table of Contents (21 chapters)
Mastering Linux Shell Scripting
Credits
About the Author
About the Reviewer
www.PacktPub.com
Preface
Index

The HTTPD log file format


When working with any a file, the first task is to become familiar with the file schema. In simple terms, we need to know what is represented by each field and what is used to delimit the fields. We will be working with the access log file from an Apache HTTPD web server. The location of the log file can be controlled from the httpd.conf file. The default log file location on a Debian based system is /var/log/apache2/access.log; other systems may use the httpd directory in place of apache2.

To demonstrate the layout of the file, I have installed a brand new instance of Apache2 on an Ubuntu 15.10 system. Once the web server was installed, we made a single access from the Firefox browser to the server from the local host.

Using the tail command we can display the content of the log file. Although, to be fair, the use of cat will do just as well with this file, as it will have just a few lines:

# tail /var/log/apache2/access.log

The output of the command and the contents...