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Checking if a specific module exists in your build of Nginx

Last Updated: [2023-03-29 Wed 07:06]

When developing a new solution that utilises Nginx, you will often end up at the Nginx documentation. From time to time, you'll find that configuration element you need, but then the following line will grab your attention at the top of the page:

This module is not built by default, it should be enabled with the --with-some_extra_module configuration parameter.

If you ever see this message in the documentation and wonder if it has been included in the build of Nginx you're using, you can check the version output of Nginx (nginx -V) which includes a list of configuration parameters used at build time.

Easy as that…

…ok, if you've actually tried this, you'll know that's not optimal. That's difficult to read. It's impossible to grep, and even if you could, the configuration options are on one line.

A bit of Bash magic is needed here:

nginx -V 2>&1 | sed -e 's/\ -/\n-/g'

That is much nicer, you can even pipe that output even further into grep and check if an individual module is installed. So for example, if you want to check the http_v2 module is available, you could run:

nginx -V 2>&1 | sed -e 's/\ -/\n-/g' | grep http_v2

So what does the first part of that one-liner do? Well, let's split it into its two parts:

nginx -V 2>&1 - This runs Nginx's version output, but the 2>&1 command forwards the stderr output to stdout, which can be manipulated and greped.

sed -e 's/\ -/\n-/g' - This will look for any dash ( - ) with a space before it, and replace it with a new line and a dash. This puts each module onto a new line for easier reading and more importantly, make it grepable.

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