Nginx Tip - Use rewrite rules for URL manipulation

Nginx is a powerful web server that is widely used for hosting websites and applications. One of its key features is the ability to manipulate URLs using rewrite rules. In this article, we will explore how to use rewrite rules in Nginx to modify and redirect URLs.

What are rewrite rules?

Rewrite rules in Nginx allow you to change the URL of a request before it is processed by the server. This can be useful for various purposes, such as redirecting old URLs to new ones, removing query parameters, or adding prefixes to URLs.

When a request is received by Nginx, it checks the URL against a set of rewrite rules defined in the configuration file. If a match is found, the URL is modified according to the rule and the request is processed accordingly.

Basic syntax of rewrite rules

The basic syntax of a rewrite rule in Nginx is as follows:

rewrite regex replacement [flag];

The regex is a regular expression that matches the part of the URL you want to modify. The replacement is the new value that will replace the matched part. The flag is an optional parameter that can be used to control the behavior of the rewrite rule.

Examples of rewrite rules

Let's look at some examples of how rewrite rules can be used in Nginx:

Redirecting old URLs to new ones

rewrite ^/old-url$ /new-url permanent;

This rule redirects any request for /old-url to /new-url with a 301 permanent redirect. The ^ and $ symbols are used to match the exact URL.

Removing query parameters

rewrite ^/page?param=value$ /page permanent;

This rule removes the query parameter param=value from the URL. The ? is used to escape the question mark, and the $ symbol is used to match the end of the URL.

Adding a prefix to URLs

rewrite ^/(.*)$ /prefix/$1 last;

This rule adds the prefix /prefix/ to all URLs. The (.*) is a regular expression that matches any characters, and the $1 is a backreference to the matched part of the URL.

Testing rewrite rules

After defining the rewrite rules in the Nginx configuration file, it is important to test them to ensure they are working as expected. Nginx provides a built-in tool called nginx -t to check the syntax of the configuration file and detect any errors.

Additionally, you can use the curl command-line tool to send HTTP requests and check the response headers. This can help you verify that the rewrite rules are correctly modifying the URLs.

Conclusion

Nginx's rewrite rules are a powerful tool for manipulating URLs. They allow you to redirect, modify, or remove parts of the URL before processing the request. By using rewrite rules effectively, you can improve the user experience and optimize your website's SEO.

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