Using awk for advanced text processing

awk is a tool designed to work with data streams. It is very interesting, as it can operate on columns and rows. It supports many built-in functionalities, such as arrays and functions, in the C programming language. Its biggest advantage is its flexibility.

Getting ready...

The structure of an awk script is as follows:

awk ' BEGIN{  print "start" } pattern { commands } END{ print "end" } file

The awk command can read from stdin also.

An awk script usually consists of three parts—BEGIN, END, and a common statements block with the pattern match option. The three of them are optional and any of them can be absent in the script.

How to do it…

Let's write a simple awk script enclosed in single quotes or double quotes, as follows:

awk 'BEGIN { statements } { statements } END { end statements }'

Or, alternately, use the following command:

awk "BEGIN { statements } { statements } END { end statements }"

For example:

$ awk 'BEGIN { i=0 } { i++ } END{ print i}' filename...