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What does %{REQUEST_FILENAME}.ext mean? Why the extra .ext ending?

Jeff

3/27/23, 12:25 PM

The %{REQUEST_FILENAME} contains a string like this:

/web/webroot/index.php

I see a lot of people recommend testing if a file exists and has a .php extension like this:

RewriteCond %{REQUEST_FILENAME}.php -f

Isn't the .php after %{REQUEST_FILENAME} redundant? The variable should already contain the .php, right?

Seems like adding .php after %{REQUEST_FILENAME} would make the TestString check add an extra .php, like this:

/web/webroot/index.php.php

I'm missing something simple, I'm sure of it, but I just don't know what it is.

The context is this:

RewriteCond %{THE_REQUEST} ^.*?\.php [NC]
RewriteRule ^ - [R=404,NE,L]

RewriteCond %{REQUEST_FILENAME}.php -f
RewriteRule ^ %{REQUEST_FILENAME}.php [L]

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mod-rewrite

apache-2.4

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MrWhite

3/27/23, 3:47 PM

Isn't the .php after %{REQUEST_FILENAME} redundant? The variable should already contain the .php, right?

Well, yes and no, it depends what you are trying to do.

RewriteCond %{REQUEST_FILENAME}.php -f
RewriteRule ^ %{REQUEST_FILENAME}.php [L]

This rule allows you to request extensionless URLs. eg. /index or /foo and this internally rewrites the request to /index.php and /foo.php respectively.

In this instance, REQUEST_FILENAME is a string of the form /web/webroot/index. So, it's testing that /web/webroot/index.php exists before rewriting to the same. If you were to request /index.php then the condition fails and no rewrite occurs (which is correct).

However, this rule isn't strictly correct and could cause a rewrite-loop under certain conditions. See the following related question:

Using Apache rewrite rules in .htaccess to remove .html causing a 500 error

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Jeff

3/27/23, 4:20 PM

I see you know your stuff. I'll stare at this for a few more hours until I figure it out. I think you're saying the variable is modified by appending the `.ext`, but I can't find this behavior documented anywhere except on SE forums. EDIT: Yeah, okay, I get it. Thanks!

MrWhite

3/27/23, 4:29 PM

@Jeff The variable itself (ie. `REQUEST_FILENAME`) isn't modified, just the _TestString_ (first argument to the `RewriteCond` directive) - as you state in the question. It's basically testing whether the requested URL + `.php` exists as a physical file. Although, `REQUEST_FILENAME` isn't strictly the correct variable to use here (although works in _most_ cases), as mentioned in the linked question. (`REQUEST_FILENAME` is the "file" that the requested URL maps to.)

Jeff

3/27/23, 4:50 PM

Well since I, of course, want to use strictly the correct variables in my code, is this the one: `%{DOCUMENT_ROOT}%{REQUEST_URI}.php -f`?

MrWhite

3/27/23, 4:53 PM

@Jeff Yes, and change the `RewriteRule` _substitution_ string accordingly. ie. `RewriteRule ^ %{REQUEST_URI}.php [L]`

Jeff

3/27/23, 4:58 PM

Awesome, thanks very much!

MrWhite

3/27/23, 6:09 PM

@Jeff The regex `!\.\w{2,4}$` excludes all requests that already include what _looks like_ a file extension. It's just an optimisation, to prevent all static resources (images, CSS, JS, etc) from being unnecessarily tested to see if `image.jpg.php` exists etc. (filesystem checks are relatively expensive). Files don't _normally_ have two file extensions like `exists.qqq.php`, so wouldn't normally be a problem. But it is just an optimisation so is safe to remove. You could achieve a similar optimisation by excluding the subdirectory where all your static assets are stored.

Jeff

3/27/23, 8:00 PM

Good stuff. Doesn't the `RewriteCond` line before the exclusion regex already exclude all those extra tests to the other static resources (besides .html files)?

MrWhite

3/27/23, 8:41 PM

@Jeff The `RewriteRule` directive is processed first. Only when the `RewriteRule` _pattern_ matches are the preceding _conditions_ processed. If the `RewriteRule` _pattern_ is not successful then the entire rule is skipped and processing continues...

Jeff

3/27/23, 8:43 PM

Wow, I did not know that. Thanks again!

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: What does %{REQUEST_FILENAME}.ext mean? Why the extra .ext ending?

TH: %{REQUEST_FILENAME}.ext หมายถึงอะไร ทำไมต้องลงท้ายด้วย .ext พิเศษ?

RO: Ce înseamnă %{REQUEST_FILENAME}.ext? De ce finalul suplimentar .ext?

RU: Что означает %{REQUEST_FILENAME}.ext? Почему дополнительное окончание .ext?

VI: %{REQUEST_FILENAME}.ext nghĩa là gì? Tại sao có thêm đuôi .ext?

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