Accessing environment variables set using mod_rewrite in PHP

Question

I have this little .htaccess file:

RewriteEngine on
RewriteRule ^(.*)$ urlroute.php?q=$1 [E=myvariable:'withthisvalue',B,QSA]

To direct all requests to my URL routing script. It works great and I can access the requested URL in urlroute.php as $_GET['q'].

I'm setting the environment variable myvariable using mod_rewrite I am able to access it in urlroute.php as $_SERVER['myvariable']. I am not able to access it using $_ENV['myvariable'] which seems strange. Could someone please explain what the reason could be?

To my knowledge, mod_redirect will prepend REDIRECT_ to environment variable names when doing a redirect (which it always does in my case). But for me both $_SERVER['myvariable'] and $_SERVER['REDIRECT_myvariable'] are available and set to the same content. Why?

Community · Accepted Answer · 2017-05-23 12:27:29Z

4

See this post also discusses the same feature. The rewrite engine loops on evaluating .htaccess files at the start of each cycle the engine copies any environment variables into a copy REDIRECT_*. Hence if the parsing of the .htaccess files requires 3 loops then you will also get REDIRECT_REDIRECT_* files, and so on.

Apache 2.3 includes a new [E] flag but you can used this feature to implement the same in earlier versions:

RewriteCond %{ENV:REDIRECT_END} =1
RewriteRule ^   -  [L]   

# other rules

...

RewriteRule somepattern  somesubst   [L,E=END:1]

AFAIK, these variables will available the SERVER context, but whether they are available in the ENVIRONMENT depends on how PHP is implemented e.g. Apache+mod_php, Apache+mod_suphp, Apache+mod_fcgi, IIS, ...

edited May 23, 2017 at 12:27

CommunityBot

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answered Feb 6, 2012 at 11:26

TerryE

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2 Comments

anubhava Over a year ago

+1 for good answer, however I think you meant RewriteCond instead of RedirectCond.

TerryE Over a year ago

@anubhava, that's what I call a "mindfart". Sorry. of course you are right. I've edited the answer

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