How to use flow Control statement in awk
This article will explain in detail how to use process control statements in awk. The editor thinks it is very practical, so I share it for you as a reference. I hope you can get something after reading this article.
There are a variety of flow control statements in awk programming, including:
If-else statement
For statement
While statement
Do-while statement
Break statement
Continue statement
Next statement
Nextfile statement
Exit statement
However, for this part of this series, we will cover: if-else, for, while, and do while statements. Keep in mind that we have described how to use awk's next statement in part 6 of this awk series.
1. If-else statement
That's what you think. The syntax of the if statement is similar to the if statement in shell:
If (condition 1) {Action 1} else {Action 2}
In the above syntax, conditions 1 and 2 are awk expressions, while actions 1 and 2 are awk commands that are executed when their respective conditions are met.
When condition 1 is satisfied, which means it is true, then Action 1 is executed and exits the if statement, otherwise Action 2 is executed.
The if statement can also be extended to the following if-else_if-else statement:
If (condition 1) {Action 1} else if (condition 2) {Action 2} else {Action 3}
For the above form, if condition 1 is true, then action 1 is executed and exits the if statement, otherwise condition 2 is evaluated and if the value is true, then action 2 is executed and exits the if statement. However, when condition 2 is false, action 3 is executed and exits the if statement.
This is an example of using the if statement, where we have a list of users and their ages, stored in the file users.txt.
We want to print a list showing whether the user's name and age are less than or over 25 years old.
Aaronkilik@tecMint ~ $cat users.txt Sarah L 35 F Aaron Kili 40 M John Doo 20 M Kili Seth 49 M
We can write a short shell script to perform our work above, which is what the script says:
#! / bin/bash awk'{if ($3
