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When working with files, you may need to remove blank lines from a file before displaying it. In Bash Script, there are several ways to remove blank lines from a file.

In this article, we will see some simple ways to remove blank lines from a file. We will discuss three different methods and look at some relevant examples and necessary explanations to make the topic easier to understand.

We will use three keywords to remove blank lines from a file and display the file. These keywords are sed, grep, and awk; we will see examples of each.

Remove empty lines from a file in Bash

Before we begin, assume we have a text file with the following content:

This is the first line.
This is the second line.

This is the third line.
This is the fourth line.

Now we will use the following three methods to remove this blank line from the file one by one,

Remove Blank Lines in Bash Using sed Keywords

In our first method, we will use sed to remove blank lines from a file. This is a built-in command in Bash.

To remove blank lines from a file, you can follow this example:

$ sed '/^[[:space:]]*$/d' 1_Test.txt

Here is the code '/^[[:space:]]*$/d'section for detecting and removing empty lines from a file.

After executing the above Bash script, you will get an output as shown below:

This is the first line.
This is the second line.
This is the third line.
This is the fourth line.

Remove Blank Lines in Bash Using grep Keyword

We can also use another built-in command in Bash called grep to eliminate blank lines. You can use this method to remove blank lines from a file as shown in the example below.

$ grep -v '^[[:space:]]*$' 1_Test.txt

Here, the code “^[[:space:]]*$”section is used to detect and remove blank lines in the file.

After executing the above Bash script, you will get the output as follows:

This is the first line.
This is the second line.
This is the third line.
This is the fourth line.

Remove blank lines in Bash using awk keywords

In this method, we will use another built-in keyword in Bash scripting also known as awk. Using this keyword, you can remove blank lines from a file by following the example below.

$ awk '!/^[[:space:]]*$/' 1_Test.txt

Here, the code section '!/^[[:space:]]*$/'is used to detect and remove blank lines from the file.

After executing the above Bash script, you will get the following output:

This is the first line.
This is the second line.
This is the third line.
This is the fourth line.

You can choose any of the above methods according to your needs.

All the codes used in this article are written in Bash. It will only work in Linux Shell environment.