Linux Tactic

Mastering the Basics of Linux Awk Command: A Comprehensive Guide

Linux is a popular open-source operating system which supports a wide range of programming languages. One such language is awk.

awk stands for Aho, Weinberger, and Kernighan (the developers of the language). Awk is a scripting language mostly used for processing and analyzing files of strings, rows, and columns.

It is known for its powerful built-in features for text processing and manipulation. In this article, we will explore the basics of the Linux awk command and the various ways it can be used to analyze and manipulate files in Linux.

We will also be providing a sample file for demonstration purposes.

Sample file used for demonstration

For the purposes of this article, we will be using a sample file that contains information on student grades. The file is organized into columns with the following headings: name, subject, professor, and pay.

Each row contains information about a particular student’s grades in a particular class. This sample file will help us demonstrate various features of awk command.

Printing and Filtering lines with awk command

The awk command is versatile and can be used in numerous ways to process files. In this section, we will look at how to use the awk command to print and filter lines from a file.

Printing all lines of a file

The most basic use of the awk command is to print all lines of a file. This can be done using the following command:

“`

$ awk ‘{print}’ filename

“`

This command will print all the lines of the file to the terminal.

Filtering lines based on a specified pattern

The awk command can be used to filter and print lines based on a given pattern. For instance, if we want to print all the lines that contain a particular word, we can use the following command:

“`

$ awk ‘/pattern/{print}’ filename

“`

where pattern is the word we want to filter on.

This command will print all lines containing the pattern.

Printing only specific columns of the file

We can use the awk command to print only specific columns of the file. For instance, if we want to print only the first and third columns of the file, we can use the following command:

“`

$ awk ‘{print $1, $3}’ filename

“`

This command will print only the first and third columns of each row in the file.

Counting the number of lines in which a pattern is matched

The awk command can also be used to count the number of lines in which a pattern appears. For instance, if we want to count the number of lines in which the word “math” appears, we can use the following command:

“`

$ awk ‘/math/{count++} END {print count}’ filename

“`

This command will print the number of lines in which the word “math” appears.

Printing only lines with more/less than a specific number of characters

The awk command can be used to print only lines with more or less than a specific number of characters. For instance, if we want to print only the lines with more than 20 characters, we can use the following command:

“`

$ awk ‘length>20’ filename

“`

This command will print only the lines with more than 20 characters.

Saving the output of the awk command to another file

The awk command can be used to redirect the output to another file. For instance, if we want to save the output of the awk command to a file called “output.txt”, we can use the following command:

“`

$ awk ‘{print}’ filename > output.txt

“`

This command will redirect the output of the awk command to a file called “output.txt”.

Printing only non-empty lines from a file

The awk command can be used to print only non-empty lines from a file. For instance, if we want to print only the non-empty lines from the file, we can use the following command:

“`

$ awk ‘NF’ filename

“`

This command will print only the non-empty lines from the file.

Counting the total lines in a file

The awk command can be used to count the total number of lines in a file. For instance, if we want to count the total number of lines in the file, we can use the following command:

“`

$ awk ‘END {print NR}’ filename

“`

This command will print the total number of lines in the file.

Conclusion

In conclusion, the awk command is a powerful tool for processing and analyzing files in Linux. It can be used in various ways to manipulate and extract information from files.

We have covered the basic usage of the awk command along with several use cases. With these examples, readers should be able to use the awk command for everyday tasks and gain a better understanding of its potential.

In summary, Linux awk command is a powerful tool that can be used to process and analyze files of strings, rows and columns. This article has highlighted various ways of using the awk command, including printing and filtering lines, extracting specific columns, counting lines, and saving outputs.

Through the use of sample files and practical examples, readers can apply the techniques discussed in this article to their everyday tasks. The ability to process text files using awk command is crucial for any Linux user or developer.

Remember that awk command can be used to automate complex tasks, which can save a lot of time and resources. Hence, it is an essential tool to learn for anyone working with text files in Linux.

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