Awk

Igor Džikajev

What is awk command?

awk is a scripting language, and it is helpful when working in the command line. It's also a widely used command for text processing. When using awk, you are able to select data – one or more pieces of individual text – based on a pattern you provide.

For example, some of the operations you can do with awk are searching for a specific word or pattern in a piece of text given, or even select a certain line or a certain column in a file you provide.

The Basic Syntax of the awk command

In its simplest form, the awk command is followed by a set of single quotation marks and a set of curly braces, with the name of the file you want to search through mentioned last.

It looks something like this:

awk '{action}' your_file_name.txt

When you want to search for text that has a specific pattern or you're looking for a specific word in the text, the command would look something like this:

awk '/regex pattern/{action}' your_file_name.txt

With information.txt file looking like this:

fristName lastName age city ID Thomas Shelby 30 Rio 400 Omega Night 45 Ontario 600 Wood Tinker 54 Lisbon N/A Giorgos Georgiou 35 London 300 Timmy Turner 32 Berlin N/A

We are able to

• Print all the contents of the file using awk '{print $0}' information.txt
• Add incrementing number before each line using awk '{print NR,$0}' information.txt
• Print specific columns using awk '{print $1}' information.txt *number represents column* It is also possible to print out multiple by adding $n after $1 awk '{print $1, $4}' information.txt or $NF to print out last column
• Print specific lines of a column by adding head or tail command to existing command // awk '{print $1}' information.txt | head -1
• Use regex awk ' /io/{print $0}' information.txt this will print out lines containing "io"
• Use comparisson operators awk '$3 < 40 { print $0 }' information.txt this will only print out lines where 3rd column (age) is <40

This wraps up everything there is to say about awk.