The requirements as stated are almost trivial. However, let's address two points -- One of them a pet peeve of mine...

The word "park" as pertains to a domain name is so imprecise as to mean nothing. What (I hope) you are doing is to "point" the various domain names to your server's IP address using DNS, and then you're configuring the server to "point" all requests for those domain names (now termed hostnames) to the same filespace (DocumentRoot in Apache-speak) on the server's disk.

Second, this sounds wrong (at a detail level):

so for example: http://example.com/test/ would redirect to http://example.com/index.php?args=test which lets the web app know that the public user asked for the "test" page...

You almost certainly don't want an external redirect here, but rather an internal rewrite; Otherwise none of your search-engine-friendly URLs such as domain.com/test/ will be listed in search engines; They'll see the redirect and replace that static URL with example.com/index.php?args=test. A redirect informs the client, and actually requires the client's participation, because the client must re-request the redirected resource using the new URL given in the initial redirect response.

In contrast, an internal rewrite just says, "If you get a request for this URL, then get the content from that file.

Risking the appearance of being pedantic, this information is meant to make things clearer for you and for those who might read or post answers here later.

A rule to internally rewrite extensionless URLs to /index.php with the URL-path as a query string, e.g. /test/ to index.php?args=test:

RewriteRule ^(([^/]+/)*[^.]+)/?$ /index.php?args=$1 [L]

Another rule to internally rewrite requests having file extensions to a domain-specific subdirectory after stripping the optional "www" subdomain and/or appended port number:

RewriteCond %{HTTP_HOST} ^(www\.)?([^:]+)(:[0-9]+)?$
RewriteRule ^(([^/]+/)*([^.]+)\.(.+))$ /sites/%2/$1 [L]

Finally, you may wish to canonicalize the domain names -- redirect to force them all to non-www or to the www subdomain:

# Externally redirect to force "www" on arbitrary (but valid) domain names
RewriteCond %{HTTP_HOST} !^www\.
RewriteCond %{HTTP_HOST} ^(([^.]+\.)+[^.:]+)(:[0-9]+)?$
RewriteRule (.*) http://www.%1/$1 [R=301,L]

--or--

# Externally redirect to remove "www" from arbitrary (but valid) domain names
RewriteCond %{HTTP_HOST} ^www\.(([^.]+\.)+[^.:]+)(:[0-9]+)?$
RewriteRule (.*) http://%1/$1 [R=301,L]

The code above is intended to be used in the top-level .htaccess file. It can be modified for use in httpd.conf by adding a leading slash to the RewriteRule patterns; e.g. change "(.*)" to "^/(.*)$" or similar.

The code above makes many assumptions about the desired behaviour, and the customization of this code is left as an exercise for the reader. Crib notes here [httpd.apache.org]. ;)

For additional information, see the documents cited in our forum charter [webmasterworld.com] and the tutorials in the Apache forum section of the WebmasterWorld library [webmasterworld.com].

Jim

jd,

Sorry about that, I mistakenly wrote "redirect" when I meant "rewrite" but thank you for clarifying...sometimes those two things are misused with the same purpose in mind.

And thanks so much for actually writing me back, and taking the time to do that. So, the first thing I did was I took the condition and rule you wrote for the file extentions and copied it into a .htaccess file with mod_rewrite turned on, and then tested it by visiting domain1.com/file.jpg which is set up to point to the web application folder that has the .htaccess file within it. For some reason, I am getting an 500 Internal Server Error. After looking at the Apache log, I found this:

[Wed Sep 12 22:14:10 2007] [error] [client 127.0.0.1] mod_rewrite: maximum number of internal redirects reached. Assuming configuration error. Use 'RewriteOptions MaxRedirects' to increase the limit if neccessary.

So I am assuming it got stuck in some infinite loop of some sort? Any thoughts here?

[edited by: jdMorgan at 4:55 am (utc) on Sep. 13, 2007]
[edit reason] De-linked [/edit]

So I have continued to play with this rule, but something about it must be causing an infinite loop. Here is my htaccess file:

<IfModule mod_rewrite.c>
Options +FollowSymLinks
RewriteEngine On

RewriteBase /

RewriteCond %{HTTP_HOST} ^(www\.)?([^:]+)(:[0-9]+)?$
RewriteRule ^(([^/]+/)*([^.]+)\.(.+))$ /sites/%2/$1 [L]

</IfModule>

what could i be doing wrong?

i am requesting the url

http://example.com/images/pic.jpg

which should return http://example.com/sites/swamped.com/images/pic.jpg

correct?

[edited by: jdMorgan at 4:56 am (utc) on Sep. 13, 2007]
[edit reason] example.com [/edit]

> what could i be doing wrong?

Or rather, as is the actual case, what might Jim have forgotten? :)

RewriteRule ^(([^/]+/)*[^.]+)/?$ /index.php?args=$1 [L]
#
[i]RewriteCond $1 !^sites/[/i]
RewriteCond %{HTTP_HOST} ^(www\.)?([^:]+)(:[0-9]+)?$
RewriteRule ^(([^/]+/)*([^.]+)\.(.+))$ /sites/%2/$1 [L]

mod_rewrite in .htaccess is recursive, and loops must be explicitly prevented.

Jim

[edit] Fixed code as noted below. [/edit]

[edited by: jdMorgan at 5:15 am (utc) on Sep. 13, 2007]

again, maybe i am missing something, but this is still not working?

I think I might have got it, you had the "does not include" sites written as a rule, when it should have been a condition so....

RewriteRule ^(([^/]+/)*[^.]+)/?$ /index.php?args=$1 [L]
#
RewriteCond $1!^sites/
RewriteCond %{HTTP_HOST} ^(www\.)?([^:]+)(:[0-9]+)?$
RewriteRule ^(([^/]+/)*([^.]+)\.(.+))$ /sites/%2/$1 [L]

that seems to work

Yeah, and I'm seriously reconsidering my habit of late-night postings... :)

Glad you got it working. I'll fix that coding error above so no one-else suffers with it -- sorry.

Jim

thanks for all your help...looks like there is another error...

if i goto

[swamped.com...]

i get this error

"Not Found

The requested URL /sites/swamped.com/index.php was not found on this server."

and i am trying to figure out what this means, can't quite understand it...

Doh!

It means another kind of unexpected redirect. The second rule is being invoked after the first rule writes a non-extension URL-path "blue" to one with an extension "index.php".

Add another exclusion to the second rule:

RewriteCond $1 !index\.php$

Too late for me...

Jim

there was one more thing wrong that i found...and Im not sure why this effected it, but it did...when i changed the first rule to this, everything was groovy...

RewriteRule ^(([^/]*/)*[^.]+)$ index.php?args=$1 [L,QSA]

i basically took out the last / is was looking for before the end