When writing shell scripts, it’s important to add comments to explain the purpose and function of the code. Comments in shell scripts are denoted by the hash symbol (#). However, sometimes you may want to write a multiline comment that spans several lines.
In this article, we will discuss how to create multiline comments in a shell script.
Method 1: Using multiple single-line comments
One way to create multiline comments in a shell script is to use multiple single-line comments. You can do this by using the hash symbol (#) on each line, followed by the comment text. Here’s an example:
1 2 3 4 5 6 7 | #!/bin/bash # This is a multiline comment # that spans several lines # and explains the purpose of the script echo "Hello, world!" |
In this example, we use three single-line comments to create a multiline comment that explains the purpose of the script.
Method 2: Using Here Documents
Another way to create multiline comments in a shell script is to use Here Documents. Here Documents are a way to include multiple lines of text within a script. Here’s an example:
1 2 3 4 5 6 7 8 9 | #!/bin/bash : <<'COMMENT' This is a multiline comment that spans several lines and explains the purpose of the script COMMENT echo "Hello, world!" |
In this example, we use a Here Document to create a multiline comment that spans three lines. The syntax for a Here Document is : <<'STRING', where STRING is the delimiter that marks the end of the Here Document. In this case, we use COMMENT as the delimiter.
Method 3: Using the : command
Finally, you can create multiline comments in a shell script using the : command. The : command is a null command that does nothing, but it can be used to create a multiline comment. Here’s an example:
1 2 3 4 5 6 7 8 9 | #!/bin/bash : ' This is a multiline comment that spans several lines and explains the purpose of the script ' echo "Hello, world!" |
In this example, we use the : command to create a multiline comment that spans three lines. The comment text is enclosed in single quotes.
Conclusion
Comments are an essential part of writing shell scripts, as they help explain the purpose and function of the code. By using the techniques discussed in this article, you can easily create multiline comments in a shell script that span multiple lines. Whether you prefer using multiple single-line comments, Here Documents, or the : command, these methods will help you write clear and concise comments in your shell scripts.