CODEWITHSUNDEEP
apachemod-rewrite
Steve
Steve

Reputation: 4898

Trying to understand a mod_rewrite script

Could someone explain how the mod_rewrite script below works? The goal is to catch an access to probe.com that has nothing following it and redirect that to probewebsites.com. If the access is to probe.com/anything, such as probe.com/register.php, the access stays at probe.com, accessing, in this case, probe.com/register.php.

The script works, I'm just not sure how.

I see that line 2 looks for an access to probe.com. Then line 3 somehow verifies that nothing is following probe.com. Line 4 looks like it's collecting a backreference, but it's never used. Thanks for any help.

1. RewriteEngine on
2. RewriteCond %{HTTP_HOST} probe\.com [NC]
3. RewriteCond %{REQUEST_URI} ^/$
4. Rewriterule ^(.*)$ http://probewebsites.com/ [L,R=301]

Upvotes: 1

Views: 58

Answers (1)

Ravi K Thapliyal
Ravi K Thapliyal

Reputation: 51711

Your general understanding about the rules is correct. Let me expand on that.

RewriteEngine on

Turns the mod-rewrite rules processing on for this directory.

RewriteCond %{HTTP_HOST} probe.com [NC]

Looks like it's looking for probe.com but it's not. Since it's a regex pattern, . would match any character. So, probeXcom would also pass; and since no regex boundaries (^, $) have been specified, it becomes a sub-string match. That means csi.probe.com or probe.com.uk would also match. The correct pattern to match only probe.com or www.probe.com would be

RewriteCond %{HTTP_HOST} ^(www\.)?probe\.com$ [NC]

^ and $ match on the start and end boundaries of the %{HTTP_HOST} which refers to the HTTP header by the same name. \. escapes the regex's match-on-any-character . and starts matching on the literal dot . character now. The question mark in (www\.)? makes the captured www. optional. Finally, [NC] stands for no case and makes the test case-insensitive.

RewriteCond %{REQUEST_URI} ^/$

This condition is actually not required because you can make the same match in the RewriteRule itself. So, the new rule should look like

RewriteRule ^$ http://probewebsites.com/ [R=301,L]

Notice, it's not ^/$ and it's not a typo. The RewriteRule pattern matches the directory path but doesn't include the leading / as in %{REQUEST_URI}.

[L] marks the rule as last since we're redirecting anyway which is specified by [R=301]. The status code 301 indicates to the browser that this redirect is permanent and so the browser will cache it. If you specify just [R], the server would do a 302 temporarily moved redirect.

So, your final .htacces should look like

RewriteEngine on

RewriteCond %{HTTP_HOST} ^(www\.)?probe\.com$ [NC]
RewriteRule ^$ http://probewebsites.com/ [R=301,L]

Upvotes: 2

Related Questions