BASH Programming

How to Block Comments in a Shell Script-Bash

In shell scripting, comments are used to annotate the code, making it easier for developers to understand the script’s purpose, functionality, and implementation. In some cases, we may want to temporarily disable or “block” certain sections of the code for debugging or testing purposes without deleting them altogether. This can be achieved using block comments in shell scripting and this article will discuss how to block comments in a shell script.

Block Comments in a Shell Script

Block comments are comments that can span multiple lines of code. In shell scripting, we can create block comments by enclosing the comments within the <<'EOF' and ‘EOF’ markers. The syntax of block comments is as follows:

: '
code line1
code line2
code line3
'

In the above syntax, the: character is used to denote an empty command that allows the block comment to be executed without generating an error. The comment text is enclosed within single quotes ‘ and can span multiple lines. The EOF markers at the beginning and end of the comment indicate the start and end of the block comment. Here’s an example of how to use block comments in a shell script:

#!/bin/bash
echo "Starting the script..."
: '
This section of the code is commented out for testing purposes.
echo "instruction not to be executed."
echo "instruction not to be executed."
echo "instruction not to be executed."
'

echo "Continuing with the script..."
echo "The script has finished."

Here, we have used block comments to temporarily disable a section of the code for testing purposes. The block comment starts with the: character, followed by the <<'EOF' marker. The comment text is enclosed within single quotes and spans three lines. The block comment ends with the ‘EOF’ marker.

Conclusion

Block comments are a useful feature in shell scripting for temporarily disabling or commenting out sections of code. By using block comments, we can easily debug and test our shell scripts without deleting or modifying the code permanently. The syntax of block comments in shell scripting is simple and easy to use. By incorporating block comments into our shell scripts, we can write cleaner and more efficient code.

About the author

Aaliyan Javaid

I am an electrical engineer and a technical blogger. My keen interest in embedded systems has led me to write and share my knowledge about them.