Mod_Rewrite 301 question

[bookbuyer2000]

Hi, I know this is a PHP forum, but some of the smartest coding people visit here... so hopefully you won't mind helping me with a mod_rewrite question.

To redirect visitors from example.com to WWW. example.com, I've seen 2 variations:

1.)
RewriteCond %{HTTP_HOST} ^example\.com
RewriteRule (.*) http://www.example.com/$1 [R=301,L]

2.)
RewriteCond %{HTTP_HOST} ^example\.com
RewriteRule ^(.*)$ http://www.example.com/$1 [R=301,L]

The 2nd variation has an extra ^ and an extra $

I don't know what those mean, but both variations seem to work on my server -- I'm sure they are different enough that one is probably "better" than the other... Which one??

Thank you!!

[halojoy]

^ symbol for absolut beginning of the text
(.*) any number of any character
$ symbol representing the absolute end of the text

in this case I dont think the two makes any difference
but other cases sure is a difference using
^ for beginning

say you want to find a string that begins with abc
^abc

only search 'abc' would give hits even inside the string, not only in beginning

[bookbuyer2000]

Originally Posted by halojoy

^ symbol for absolut beginning of the text
(.*) any number of any character
$ symbol representing the absolute end of the text

Thank you for explaining that! However, looking at the example using the ^ and the $, I can't figure out what it's doing there before the "http" part.
Since it is before the "http" part, does that mean if someone types a bunch of stuff *before* the http in the browser? I've never heard of that. I wonder what an example would be of that.

[dagon]

^ = Start of line anchor
$ = End of line anchor


in some case it's clear with out them in other cases without them the rewrite will fail, so its best to use them.

$index.html^

is only going to match index.html

where as

$index.html

would also match

index.html-and-anythinjg-after-it

since .* in your cases matches everything anyway there's no obvious value to them


Module mod_rewrite URL Rewriting Engine

[dagon]

Originally Posted by bookbuyer2000

Thank you for explaining that! However, looking at the example using the ^ and the $, I can't figure out what it's doing there before the "http" part.
Since it is before the "http" part, does that mean if someone types a bunch of stuff *before* the http in the browser? I've never heard of that. I wonder what an example would be of that.

The rule has 2 parts Pattern and Substitution

in your case pattern =

^(.*)$

Substitution=

http://www.example.com/$1

you are replacing anything with http://www.example.com/*What you match*

[bookbuyer2000]

Originally Posted by dagon

The rule has 2 parts Pattern and Substitution

in your case pattern =

^(.*)$

Substitution=

http://www.example.com/$1

I think I understand. the ^(.*)$ part does seem redundant though -- I just can't see what circumstance that would ever be necessary. If you have an example, it would help me learn (if convenient for you to provide example).

May I also ask: what exactly does the "/$1" part do? I thought $1 is just a backreference... but I can't figure out what that's backreferencing? Does it mean that if the website visitor types in variables, that should get appended, too? For example: http://example.com/index.html?item=red

[dagon]

$1 is what ever the (.*) matches

if you had (foo)(bar)

you can use $1 =foo, $2=bar