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tech 1 September 2026

Say Goodbye to Redundancy with M4

Learn how to cut down code repetition in httpd configurations with M4, a powerful tool for developers using OpenBSD.

Article inspired by the original source
Repeating Ourselves Less with M4 ↗ nemin.hu

Introduction

As a developer, you know how code redundancy can be a real pain, especially when dealing with configuration files like httpd.conf on OpenBSD. Fortunately, the M4 tool is here to save the day. In this article, we'll explore how M4 can reduce redundancy and simplify your development process.

What is M4?

M4 is a macro preprocessor that allows you to define macros to automate repetitive tasks. Unlike other macro systems that manipulate the abstract syntax tree, M4 is a "dumb" expression expander. It doesn't understand your language's syntax but is highly effective at text manipulation. This means you can use it to transform your code flexibly, though it can also lead to errors if you're not careful.

Why Use M4?

  1. Efficiency: Reducing redundancy allows you to focus on actual development rather than repeating trivial tasks.
  2. Readability: A shorter configuration file is easier to read and maintain.
  3. Modularity: Macros let you create reusable code blocks.

Practical Application with httpd.conf

Let's take a concrete example. Suppose you need to block several malicious routes in your httpd.conf file. Instead of copying and pasting the same block of code multiple times, you can create an M4 macro to handle this for you.

M4 Macro Example

``m4 m4_define(BLOCK_ROUTE', block route $1 { deny all }') BLOCK_ROUTE(/malicious/path1') BLOCK_ROUTE(/malicious/path2') ``

In this example, the BLOCK_ROUTE macro significantly simplifies the process of blocking routes. This makes the configuration file cleaner and easier to manage.

Pros and Cons

Pros

  • Significant time savings: Less repetition means more time for other critical tasks.
  • Fewer human errors: Less copy-pasting reduces the risk of inadvertently introducing errors.

Cons

  • Learning curve: If you've never used M4, there's a learning period.
  • Potential complexity: Overuse of macros can make the code difficult to understand for newcomers.

Conclusion

Using M4 to reduce repetition in configuration files like httpd.conf is a winning strategy for developers looking to optimize their workflow. If you're ready to explore how M4 can transform your development approach, let's discuss your project in 15 minutes.

References

  • OpenBSD [Documentation](https://www.openbsd.org/)
  • GNU M4 Guide [Link](https://www.gnu.org/software/m4/)

Call to Action

Let's discuss your project in 15 minutes.

M4 OpenBSD Macros httpd.conf Code Redundancy
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