CODEWITHSUNDEEP
phpapache.htaccesshttp-redirectmod-rewrite
foolstack
foolstack

Reputation: 23

Decipher this .htaccess line

# Redirect all users to access the site WITH the 'www.' prefix
RewriteCond %{HTTP_HOST} !^www\. [NC]
**RewriteCond %{HTTP_HOST} !\.([a-z-]+\.[a-z]{2,6})$ [NC]**
RewriteRule ^ http://www.%{HTTP_HOST}%{REQUEST_URI} [L,R=301]

Ok, so in the above code I think the 1st line says "if the URL does not have www." and then the 3rd line says to "rewrite the URL with the www. as a 301 redirect", but the 2nd line I believe is to take into consideration subdomains and exclude them, but can anyone tell me what this !\.([a-z-]+\.[a-z]{2,6})$says exactly?

Another question: if mod_rewrite is enabled do I still need to add RewriteEngine Onto the top of the .htaccess file? What happens if I don't?

Upvotes: 0

Views: 66

Answers (1)

zefixlluja
zefixlluja

Reputation: 468

The regular expression on the second line matches, if the string:

  • ! does not have
  • \. a literal dot, followed by
  • [a-z-] multiple characters of the a-z,- range, followed by
  • \. another literal dot, followed by
  • [a-z]{2,6} between 2 and 6 characters from the a-z range
  • $ before the end of the string

The parenthesis "(..)" allow capturing of a matched substring. This can then be used in following expression/substitutions.

The NC flag will cause the match to performed case-insensitive.

In your case this will trigger a rewrite if the incoming URL

  • does not start with www. (1st line)
  • does not end with sth that looks like .hostname.tld (2nd line)

See https://regex101.com/ for a good playground to experiment with regular expressions.

Upvotes: 1

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