Wrapping the Built-in Bash Command export for Logging Variables

Discover how to effectively wrap the Bash built-in command `export` to add logging functionality in your shell scripts.
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Wrapping the Built-in Bash Command export for Logging Variables

Bash scripting can sometimes feel limiting, especially when you want to add extra functionality to built-in commands. One common request among scripters is to wrap a built-in command to enhance it, such as adding logging for when environment variables are exported. This guide will guide you through the process of wrapping the export command in Bash to achieve this goal.

The Challenge: Wrapping Built-ins in Bash

When working with built-in commands in Bash, one might wonder about the best way to enhance them without completely losing their original functionality. For example, consider the need to log each variable that gets exported using the export command. In other programming languages like JavaScript, you can override built-in functions relatively easily by saving a reference to the original function.

However, Bash lacks the concept of references in the same way that JavaScript does, leading many to believe that wrapping built-ins might not be possible. Fortunately, there is a method to achieve this functionality in Bash using the builtin command.

The Solution: Creating a Wrapper Function

You can create a wrapper function around the export built-in command and still maintain access to the original command. Here’s how to do it:

Step-by-Step Implementation

Define the Function: Start by defining a function named export that will replace the original built-in command.

Log the Arguments: Inside this function, utilize the echo command to log the arguments that are being passed to the export.

Call the Original Built-in Command: Finally, use the builtin command in Bash to call the actual, original export command.

Example Code

Here’s the code that accomplishes this:

[[See Video to Reveal this Text or Code Snippet]]

Explanation of the Code

Function Definition: The function export() creates a new command that will execute every time you use export in your script.

Logging with Echo: The echo "Exporting: $@ " line logs all arguments passed to the function, where "$@ " represents all parameters.

Calling the Original Command: The line builtin export "$@ " ensures that after logging, the built-in export command runs as expected with the original arguments.

Conclusion

By using this simple technique, you can effectively log every variable that gets exported in your Bash scripts, enhancing export without losing its fundamental behavior. This method demonstrates the flexibility of Bash scripting and how you can harness built-ins for more customized logging and functionality.

Next time you need to wrap a built-in command in Bash, remember this approach! It not only keeps your logs organized but also ensures that your scripts run smoothly without any disruption to the expected output.