While the commands we have covered so far can display text files in various ways, sometimes we may need to perform additional operations on the text. In such cases, we can use the awk command.

awk is a powerful command-line tool that allows you to search for patterns in a file and perform actions based on those patterns. It works by scanning through a file one line at a time and applying a set of actions to each line that matches a pattern.

The basic syntax for awk is as follows:

Here, pattern specifies the search pattern, and action specifies the action to be performed on the lines that match the pattern. For example, if we want to display only the first column of a text file, we can use the following command:

This will display only the first column of file.txt.

In addition to this basic syntax, awk also provides a number of built-in variables and functions that can be used to manipulate text. For example, the NF variable contains the number of fields in a line, and the length() function returns the length of a string.

Here's an example of how to use awk to print the length of each line in a file:

This will display the length of each line in file.txt.

awk is a very powerful tool, and we have only scratched the surface of its capabilities. If you're interested in learning more about awk, there are many great resources available online.

That concludes our overview of the command line tools for working with text files. In the next module, we will cover some essential Linux commands for working with directories and files.