How to Enable Apache Rewrite (mod_rewrite) Module

Apache’s mod_rewrite is one of the most powerful modules available for URL manipulation. With mod_rewrite, you can redirect URLs, rewrite URLs to make them cleaner, and much more. It is particularly useful for implementing SEO-friendly URL structures on your website. In this article, we will walk you through how to enable mod_rewrite in Apache on both Debian-based and RHEL-based systems.

1. Check if mod_rewrite is Already Enabled

Before enabling mod_rewrite, it’s a good idea to check if it’s already active:

apache2ctl -M | grep rewrite

httpd -M | grep rewrite

If you see `rewrite_module (shared)`, then mod_rewrite is already enabled.

2. Enabling mod_rewrite

Now enable the mod_rewrie module in Apache web server based on your operating system.

On Debian-based Systems (like Ubuntu):

Use these steps on Debian-based systems like, Ubuntu, Debian, Linux Mint systems.

Install Apache (if not already installed):

sudo apt update 
sudo apt install apache2

Enable mod_rewrite:
```
sudo a2enmod rewrite 
```
Restart Apache to apply changes:
```
sudo systemctl restart apache2 
```

On RHEL-based Systems (like CentOS):

Use these steps on RHEL-based systems like, Fedora, CentOS, Scientific Linux, Amazon Linux and RedHat systems.

Install Apache (if not already installed):
```
sudo yum install httpd 
```
Enable mod_rewrite: The module is typically enabled by default on RHEL-based systems. If not, you can manually load it by editing the Apache configuration. Edit the main Apache configuration file using a text editor like vi or nano:
```
sudo nano /etc/httpd/conf/httpd.conf 
```
Then, ensure that the following line is present and not commented out:
```
LoadModule rewrite_module modules/mod_rewrite.so
```
Restart Apache to apply changes:
```
sudo systemctl restart httpd 
```

3. Configuring .htaccess for mod_rewrite

For mod_rewrite rules to work from .htaccess files, you must ensure that the directory configurations allow for overrides.

In the Apache configuration file (usually /etc/apache2/apache2.conf on Debian-based systems or /etc/httpd/conf/httpd.conf on RHEL-based systems), find the section for your website’s document root and modify the `AllowOverride` directive:


<Directory /var/www/html>
    AllowOverride All
</Directory>

After making changes, always remember to restart Apache.

4. Testing mod_rewrite

To ensure that mod_rewrite is working correctly, you can set up a basic rule in an .htaccess file:

In your document root (e.g., /var/www/html), create or edit the .htaccess file:
```
nano /var/www/html/.htaccess 
```

Add the following content:


RewriteEngine On
RewriteRule ^hello\.html$ welcome.html [R=302,L]

Now, create a welcome.html file:
```
echo "Welcome, TecAdmin!" > /var/www/html/welcome.html 
```
Accessing http://your_server_ip/hello.html should now redirect you to http://your_server_ip/welcome.html.

Conclusion

Enabling and configuring mod_rewrite in Apache can greatly improve the flexibility and SEO-friendliness of your website URLs. Just make sure to plan and test your rewrite rules carefully, as mistakes can result in inaccessible pages or infinite redirect loops.