Linux awk command

The Linux awk command is a versatile tool for processing and manipulating text data in a straightforward and efficient manner. By using patterns and actions, awk can search for specific content, extract data, perform calculations, and generate reports. With its ability to work with fields, records, variables, and functions, awk is well-suited for a wide range of text processing tasks. Whether you need to reformat log files, extract specific information from a dataset, or automate data processing tasks, awk is a valuable addition to any command-line toolkit.

awk Syntax:

awk [options] 'pattern { action }' file

Options:

Option	Description
-F	Specifies the field separator.
-v	Assigns a value to a variable.
-f	Specifies a file that contains the AWK script.
-F	Specifies the field separator.
-r	Enables extended regular expressions.

Parameters:

Parameter	Description
’pattern { action }‘	Specifies the pattern and corresponding action to be performed.
file	Specifies the input file.

awk Usage:

Print Specific Columns from a File

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

This command will print the first and third columns from the file.txt.

Search for a Specific Value in a File

awk '/searchterm/' file.txt

Searches for the term “searchterm” in file.txt and prints lines containing it.

Calculate Total Value of a Column

awk '{sum+=$1} END {print sum}' file.txt

Calculates the total sum of values in the first column of file.txt.

Print Lines Longer Than a Specific Length

awk 'length($0) > 50' file.txt

Prints lines in file.txt that are longer than 50 characters.

How do I use awk in Linux?

To use the awk command in Linux, execute the following command:

awk '{print $1}' file.txt

What is the purpose of awk ‘{print $1}’ command?

The command awk '{print $1}' is used to print the first field of each line in the input file. Using $1 as the field reference specifies the first field, so this command will print the first column or word in each line.

How can I specify a delimiter for awk?

You can specify a delimiter for awk using the -F option followed by the delimiter character. For example, to use a comma as the delimiter, you would run:

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

How can I perform calculations with awk?

To perform calculations with awk, you can use arithmetic operators like +, -, *, / within the action part. For example, you can add the values in the second column and print the result:

awk '{sum+=$2} END {print sum}' file.txt

How do I filter data with awk?

To filter data with awk, you can specify a condition in the pattern part. Only lines that match the condition will have the specified action performed. For example, to print lines where the first column is greater than 10:

awk '$1 > 10 {print}' file.txt

How can I use awk to format output?

You can use the printf function within awk to format and print output in a specific way. For instance, to print the first two columns with a specific format:

awk '{printf "Name: %-10s Age: %d\n", $1, $2}' file.txt

How can I read input from a pipe with awk?

You can read input from a pipe with awk by using a dash - as the filename. For example, to process output from another command using awk:

ls -l | awk '{print $9}'

Applications of the awk Command

Processing and analyzing text files
Generating reports and summaries
Searching and replacing text
Extracting specific data fields
Formatting data for further processing
System administration tasks
Text manipulation and transformation