Use case examples of pattern matching using AWK

In this section, we illustrate the workings of AWK using some practical examples such as the parsing of web server log files, transposing the contents of files, and processing multiple files.

Parsing web server (Apache/Nginx) log files

In this section, we will see how AWK can be used for generating reports fromlog files.Using AWK, we can segregate the different portions of log files to find the bottleneck of different issues that are creating extensive memory usage, CPU usage, or I/O on servers.

We will use a sample log file namedapache_logs.txt for performing the practice here.

Understanding the Apache combined log format

Before analyzing the log file of web servers, let's look at the log file format. A standard log file entry contains the following information:

%h %l %u %t “%r” %>s %b “%{Referer}i” “%{User-agent}i

Here is a description of the different fields used in the combined log format:

• %h: IP address of the client (remote host) making the...