Creating Apache Virtual Hosts with sed Using a Template

Описание: Learn how to efficiently create Apache virtual host files using `sed`, leveraging a template and a list of server names.
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This video is based on the question https://stackoverflow.com/q/75430497/ asked by the user 'a3kartik' ( https://stackoverflow.com/u/6203951/ ) and on the answer https://stackoverflow.com/a/75430598/ provided by the user 'Tyler Harrison' ( https://stackoverflow.com/u/8009114/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Creating Apache Virtual Hosts with sed Using a Template

Setting up multiple Apache virtual hosts can often feel like a daunting task, particularly when you have a template file and a list of server names. Fortunately, with the power of the sed command-line tool, you can automate this process, making your life much easier in the long run. In this guide, we will walk through a solution to a common problem faced by system administrators: generating virtual host configuration files from a template.

The Problem

Imagine you have a template file (dlist1) that contains the configuration for an Apache virtual host. You also have a list of server names stored in a separate file (server_name_list). Your aim is to create individual configuration files for each server listed where certain placeholder strings (like DIR) in the template will dynamically change to match the server name.

Template File Example: /tmp/dlist1

Here is what our template file looks like:

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

Server Name List: /tmp/server_name_list

Our list of server names is as follows:

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

We want to generate separate .conf files for each server based on this template. For example, the configuration for abc.com should look like this:

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

The Solution

To achieve this automation, we will use a simple bash script integrated with sed. Below is the step-by-step breakdown of the solution:

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

Breakdown of the Script

Iterate Over Server Names:

The for j in \cat server_name_list`` line reads every line (server name) from the server_name_list file.

Remove the Domain Extension:

The line j="${j%.*}" uses parameter expansion to remove the .com extension from each server name. This allows us to use abc, xyz, and utv as directory names instead of abc.com, etc.

Use of sed:

The command sed "s/DIR/$j/g" dlist1 replaces all occurrences of the string DIR in the template file dlist1 with the current server name stored in j.

The g at the end signifies a global replacement — this means it will replace every instance of DIR in the file.

Output Redirection:

Finally, the output is redirected to a new file named $j.conf, thus creating abc.conf, xyz.conf, and utv.conf respectively.

Conclusion

With just a few simple commands, you can easily generate multiple Apache virtual host configuration files from a single template. Using sed and bash for automation not only saves time but also reduces the potential for errors that can occur when manually editing each configuration file.

We hope this guide helps you set up your Apache virtual hosts with ease. Happy coding!