Introduction to AWK Training

Home to training index page > Scripting and automation > Introduction to AWK training

What is AWK?

AWK is a versatile programming language used for text processing and data analysis. It is especially useful for processing large text files, and for extracting and manipulating data from structured text such as CSV and log files. In this user guide, we will cover the basics of AWK scripting, including variables, loops, and conditionals, and provide examples of how to use AWK for text processing.

AWK Basics

AWK programs consist of a series of patterns and actions. The pattern is a regular expression that matches a specific set of records, and the action is the command that is executed on the records that match the pattern. Here is an example of an AWK program:

awk '/foo/ {print $1}' file.txt

In this program, /foo/ is the pattern that matches all records that contain the string “foo”. The action {print $1} prints the first field of each record that matches the pattern.

AWK Variables in this training

AWK supports several built-in variables that can be used in AWK programs. Here are a few of the most commonly used variables:

NF: The number of fields in the current record.
NR: The number of the current record.
$0: The entire current record.
$1: The first field of the current record.
$2: The second field of the current record.

Here’s an example of how to use these variables in an AWK program:

awk '{print NR, NF, $1, $NF}' file.txt

This program prints the record number, the number of fields in the record, the first field, and the last field of each record in the file.

AWK Loops in this training

AWK supports several types of loops, including the for loop, the while loop, and the do-while loop. Here’s an example of how to use a for loop in an AWK program:

awk '{for (i=1; i<=NF; i++) print $i}' file.txt

This program loops through each field in each record in the file, and prints each field on a separate line.

AWK Conditionals in this training

AWK supports several conditional statements, including if, else, and else if. Here’s an example of how to use an if statement in an AWK program:

awk '{if ($1 == "foo") print $0}' file.txt

This program prints all records in the file where the first field is equal to “foo”.

Conclusion

AWK is a powerful programming language for text processing and data analysis. By following the basics outlined in this user guide and practicing with examples, you can use AWK to manipulate and extract data from text files.