What is Awk Command in Linux?
Here we will understand the concept of Awk command in Linux. You will also find its features, AWK Script, along with examples.
Awk Command
Linux uses the awk command for text processing. Although the sed command is also used for text processing, it has significant drawbacks, making the awk command a useful alternative. It gives the data strong control. For text scripting, Awk is a powerful scripting language. It involves searching and replacing the texts and sorting, checking, and indexing the database. This article will discuss more awk commands in Linux.
You can also explore: Linux courses
Best-suited Linux courses for you
Learn Linux with these high-rated online courses
Features of AWK command in Linux
The Awk command has the following features:
- Line by line, a file is scanned.
- A file is divided into various fields by it.
- It contrasts the text that is input or a section of a text file.
- It performs numerous operations on a file, such as searching for a particular text.
- The lines of output are formatted.
- It can operate on strings and numbers.
- It applies the criteria and loops based on the results.
- It modifies the data and files on a given structure.
- It generates reports in the format.
Read Also: What is Operating Systems – Types, Function, and Example
Syntax:
Here’s a demonstration of how to use the awk command:
awk options 'selection _criteria {action }' input-file > output-file
Options include:
-f program files: It examines the script’s source code, which was written using the awk tool.
-F fs: It serves as the field separator for the input.
Must Check: Operating Systems Online Courses and Certifications
How to Define AWK Script?
Use the awk command, curly braces, and a single quote mark to define the awk script. For example
awk '{ print "Welcome Awk command"}'
Must read: Difference between Linux and Unix
AWK Command Examples
Look at the example below to learn more about the Awk command:
To apply the various awk operations, let’s establish a data set. Think about the student data from various streams.
Use the cat command as follows to generate data:
cat > studentlist.txt Ava CS Dani IT John CS Alex IT Micheal ECE Helena CS
On the created student data, we will use the awk command.
Also check: Learn Basic Linux Commands (With Syntax)
Example 1: List the students who fit the required pattern.
Consider the below command:
awk '/ CS/ {print} ' studentlist.txt
Example 2: Find the default behavior of the awk command
We will get the file’s entire contents if we don’t specify a pattern.
Have a look at the command below:
awk '{print}' studentlist.txt
Example 3: Print the specified column.
This command will only print that line if we supply the column number. Think about the result below.
awk '{print $1,$5} studentlist.txt
Built-in Variables in AWK Command
Numerous built-in variables supported by the awk tool divide the file’s content into smaller chunks, including $1, $2, and others.
NR: It is utilized to display the number of lines as of the moment. For each line, the awk program executes an operation once. These are records.
NF: It is employed to determine the many fields in the current database.
FS: To divide fields into input lines, it is used to build a field separator character.
ORF: The output field separator is kept there for further use. The output fields are divided by this.
OFS: The output record separator is stored in the ORS. The output records are divided by this. It automatically prints the ORS command’s contents.
Suggested Read: Linux vs Windows
Example 4: Print the output and display the line number.
Use the NR variable in conjunction with the Awk command, as shown below, to display the line number in the output:
awk '{print NR,$0}' studentlist.txt
Example 5: Print the last field of the file.
Use the NF variable along with the Awk command to display the last field of the file:
awk '{print $NF}' studentlist.txt
Example 6: Separate the output in the specified format.
To separate the output by a ‘-‘ symbol or (:) semicolon, specify it with the ORS command as follows:
awk 'BEGIN { ORS ="-"} {print $0}' studentlist.txt
We can use the underscore (_) symbol in the command above to denote output separation. Think about the result below:
Ava CS -Dani CS-John CS-Alex IT-Micheal ECE-
Example 7: Print the square of the numbers from 1 to 8.
Execute the following command to print the numbers from 1 to 8:
awk 'BEGIN { for(i=1;i<=8;i++) print "square of", i, "is",i*i; }'
Example 8: Calculate the sum of a particular column.
Create a data set and then apply the sum operation to a column. Use the cat command to create student marks data as follows:
naukrilearning@ naukrilearning -GB-BXBT-2807:~$ cat > student_marks Name, Marks, Max marks Ava,75,100 Dani,80,100 John,74,100 Alex,85,100 Micheal,70,100 Helena,74,100
To save the file, press CTRL+D. The data for student_marks has been produced successfully. By using the cat command as follows, we can verify it:
cat student_marks
Execute the following command to calculate the third column of the generated data:
awk -F"," '{x+=$3}END{print x}' student_marks
Example 9: Find some of the individual records.
Execute the following command to print some of the individual student marks records:
wk -F, '{a[$1]+=$2;}END{for(i in a)print i", "a[i];}' student_marks
Example 10: Find the value of exp 8.
Execute the following command to find the value of exp 8:
awk 'BEGIN{x=exp(8); print x}'
Also Read: Top Linux Interview Questions and Answers
Conclusion
Companies can employee Unix AWK Command Shell scripting for sophisticated text processing. We can typically use Awk Command in Linux as a reporting tool and for pattern matching. Awk can perform a set of operations on the input file.
Contributed By: Megha Chadha
This is a collection of insightful articles from domain experts in the fields of Cloud Computing, DevOps, AWS, Data Science, Machine Learning, AI, and Natural Language Processing. The range of topics caters to upski... Read Full Bio
Top Picks & New Arrivals
