What is AWK Command in Linux with Examples?

Cloudtechtiq January 25, 2025

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When it comes to powerful text-processing tools in Linux, AWK stands out as one of the most essential and flexible utilities. Whether you’re a system administrator, developer, or data analyst, learning how to use AWK can make working with text files, logs, or structured data a lot more efficient. In this blog, we will explore What is AWK Command in Linux, its syntax, and key features, and provide practical examples to help you become proficient in using it.

What is AWK Command in Linux?

AWK is a domain-specific programming language designed for text and data processing. It’s primarily used for pattern scanning and processing. It takes its name from the initials of its creators: Alfred Aho, Peter Weinberger, and Brian Kernighan—the trio who developed it in the 1970s as part of the UNIX operating system.

AWK excels at tasks like extracting data, transforming it, generating reports, and performing calculations, all of which can be done in one simple command. It’s commonly used in log file analysis, CSV file processing, and automating tasks that involve structured data.

Why AWK?

AWK is highly valued for:

Pattern Matching: AWK uses regular expressions to search for specific patterns in the input data.

Field-Based Processing: AWK treats each line of input as a series of fields (columns), making it perfect for working with delimited data.

Simplicity and Flexibility: With a simple syntax, AWK allows users to perform complex text-processing tasks efficiently.

AWK’s combination of simplicity, speed, and powerful text-processing capabilities makes it a must-learn for anyone working in a Linux environment.

Basic Syntax of the AWK Command

The syntax of an AWK command is:

pattern: This is the condition that triggers the action. It can be a specific string, regular expression, or a logical expression.
action: This defines what to do when the pattern matches. Actions are enclosed in curly braces { } .
input_file: The file you want to process. If omitted, AWK will read from standard input (stdin).

Key Features of AWK

Field-Based Processing: AWK reads input files line by line and splits each line into fields, using spaces or tabs by default as separators. Fields are denoted by $1 , $2 , $3 , etc., where $1 is the first field, $2 is the second, and so on. The entire line is represented by $0 .

Built-in Variables: AWK provides several built-in variables for text processing:

NR : Number of records (lines) processed so far.

NF : Number of fields in the current record.

$0 : The entire current record (line).

$1 , $2 , …: The individual fields in the current record.

BEGIN and END Blocks:

BEGIN Block: This block is executed before any input is read. It’s useful for initializing variables or printing headers.

END Block: This block is executed after all the input has been processed. It’s useful for summarizing the data or printing final results.

Example 1: Printing Specific Columns

Printing Specific Columns

Let’s say you have a file people.txt with the following content:

If you want to print just the names (the first column), you can run the following AWK command:

Printing Specific Columns

Output:

Here, $1 refers to the first field of each line (the name), and AWK prints it. You could replace $1 with $2 to print the second column (the age), or $3 for the gender.

Example 2: Filtering Data with Conditions

AWK is incredibly useful when you need to filter data based on specific conditions. For example, if you want to print records where the age is greater than 25, use the following command:

Output:

Here, the condition $2 > 25 checks if the second column (age) is greater than 25, and if the condition is true, the entire line is printed using $0 .

Using BEGIN and END Blocks

Example 3: Using BEGIN and END Blocks

AWK allows you to execute certain actions before and after processing the file. This is especially useful for printing headers or performing summarization. Here’s an example where we print a header before processing the data, and a footer after processing:

Using BEGIN and END Blocks

Output:

The BEGIN block prints the column headers, the { print $1, $2, $3 } block prints the data from the file, and the END block prints a footer.

Example 4: Calculating Values

Calculating Values

AWK is also great for performing calculations on numeric data. Suppose you have a file sales.txt with the following content:

If you want to calculate the total sales amount, you can use the following AWK command:

Output:

Here, $2 refers to the second column (sales amounts), and sum += $2 adds each sales figure to the sum variable. The END block prints the total.

Example 5: Custom Field Separators

By default, AWK uses spaces or tabs to separate fields. However, if your data is delimited by commas (e.g., a CSV file), you can specify a custom delimiter using the -F option. For example, for a file data.csv :

You can set AWK to treat commas as field separators:

Custom Field Separators

Output:

Here, -F , sets the field separator to a comma.

AWK is one of the most powerful and efficient tools for text processing in Linux. Whether dealing with structured data like CSV files, analyzing logs, or generating reports, AWK’s concise syntax and rich feature set make it indispensable for a wide range of tasks.

Learning to use AWK effectively allows you to automate complex text-processing workflows, save time, and significantly improve your productivity in handling and manipulating data.

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The examples in this post are just the beginning. AWK offers rich features, including advanced string manipulation, array support, and more, allowing you to create sophisticated data processing scripts. Experimenting with these features and incorporating AWK into your day-to-day work can vastly improve your efficiency in managing and analyzing data in Linux environments. Hope you like our blog article on What is AWK Command in Linux! Don’t forget to share this blog with your friends.