Exploring awk - Linux Commands

What is the awk Command in Linux?

The awk command in Linux is a versatile and powerful text-processing tool, often used for pattern scanning and data extraction. Named after its creators (Aho, Weinberger, and Kernighan), awk works on files or input streams, scanning each line and applying operations based on specified patterns or conditions. It’s often used in shell scripts for data extraction, transformation, and reporting.

Basic syntax:

awk 'pattern {action}' file

Example:

awk '{print $1}' file.txt

Options

Option	Description
-F	Sets the field separator (default is space or tab)
-f	Reads the awk program from a file instead of the command line
-v	Allows you to pass in external variables

Common Use Cases

Printing Specific Columns

One of the most popular awk use cases is extracting columns from a file:

awk '{print $2}' file.txt

This command prints the second column from each line of the file. You can combine columns too:

awk '{print $1, $3}' file.txt

Filtering Data with Patterns

You can filter data based on specific conditions, like printing lines that contain a certain word:

awk '/pattern/ {print}' file.txt

For example, to print lines that contain the word “error”:

awk '/error/ {print}' log.txt

Field Separator

Sometimes your data might be separated by something other than spaces or tabs (like commas in CSV files). You can tell awk to use a different delimiter with the -F option:

awk -F, '{print $1, $2}' data.csv

Calculations and Summarization

awk is also useful for simple calculations, such as summing values in a column:

awk '{sum += $3} END {print sum}' file.txt

This command sums all values in the third column of file.txt.

Print Line Numbers

If you want to print lines along with their line numbers, awk can handle that too:

awk '{print NR, $0}' file.txt

Here, NR is a built-in variable that represents the current line number, and $0 refers to the entire line.

Additional Help

You can explore more by using the commands:

man awk

Resources

AWK - Basic Examples

Getting Started With AWK Command [Beginner’s Guide]

History of awk and gawk

Thank you!

Thank you for your time and for reading this!