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Mod rewrite » History » Revision 37

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dandv, 2008-07-14 05:34
Added information about regexp matching anything BUT an expression


TracNav(DocsToc) {{{
#!rst ============
URL Rewrites ============

-------------------
Module: mod_rewrite
-------------------

.. meta::
:keywords: lighttpd, rewrite

.. contents:: Table of Contents

Description ===========

internal redirects, url rewrite

Options =======

url.rewrite-once
rewrites a set of URLs internally in the webserver BEFORE they are handled.

e.g. ::
url.rewrite-once = ( "<regex>" => "<relative-uri>" )

url.rewrite-repeat
rewrites a set of URLs internally in the webserver BEFORE they are handled

e.g. ::
url.rewrite-repeat = ( "<regex>" => "<relative-uri>" )

The difference between these options is that, while url.rewrite-repeat allows for applying multiple (seperately defined) rewrite rules in a row, url.rewrite-once will cause further rewrite rules to be skipped if the expression was matched. As such, url.rewrite-once behaves like Apaches' RewriteRule ... [L]: http://httpd.apache.org/docs/2.2/mod/mod_rewrite.html#rewriterule

The options ``url.rewrite`` and ``url.rewrite-final`` were mapped to ``url.rewrite-once``
in 1.3.16.

NOTE: url rewriting does not work within a $HTTP["url"] conditional. [http://forum.lighttpd.net/topic/1092#3028]

Regular Expressions ===================

  • Patterns ("wildcards") are matched against a string
  • Special characters (see [http://www.regular-expressions.info/reference.html] for reference):
    • . (full stop) - match any character
    • \* (asterisk) - match zero or more of the previous symbol
    • \+ (plus) - match one or more of the previous symbol
    • ? (question) - match zero or one of the previous symbol
    • \\? (backslash-something) - match special characters
    • ^ (caret) - match the start of a string
    • $ (dollar) - match the end of a string
    • [set] - match any one of the symbols inside the square braces.
    • (pattern) - grouping, remember what the pattern matched as a special variable
    • {n,m} - from n to m times matching the previous character (m could be omitted to mean >=n times)
    • (?!expression) - match anything BUT expression at the current position. Example: ``"^/((?:(favicon.ico$|js/|images/).*)" => "/fgci/$1"``
  • Normal alphanumeric characters are treated as normal

Replacement Patterns
--------------------

If the matched regex contains groups in parentheses, $1..$9 in the replacement refer to the captured text in the
matching group "$1" meaning the first group, "$2" the second, and so on.

You can also use certain meta-patterns in replacement text (NOTE: these inferred from examples in other modules, but unverified yet.):

  • %% => % sign
  • %0 => domain name + tld (Top Level Domain, like .com or .net)
  • %1 => tld
  • %2 => domain name without tld
  • %3 => subdomain 1 name
  • %4 => subdomain 2 name

Examples ========

The regex is matching the full REQUEST_URI which is supplied by the user including
query-string.::

url.rewrite-once = ( "^/id/([0-9]+)$" => "/index.php?id=$1",
"^/link/([a-zA-Z]+)" => "/index.php?link=$1" )
  1. the following example, is, however just simulating vhost by rewrite
  2. * you can never change document-root by mod_rewrite
  3. use mod_*host instead to make real mass-vhost
  1. request: http://any.domain.com/url/
  2. before rewrite: REQUEST_URI="/www/htdocs/url/"
  3. and DOCUMENT_ROOT="/www/htdocs/" %0="any.domain.com" $1="url/"
  4. after rewrite: REQUEST_URI="/www/htdocs/any.domain.com/url/"
  5. still, you have DOCUMENT_ROOT=/www/htdocs/
server.document-root = "/www/htdocs/" 
$HTTP["host"] =~ "^.*\.([^.]+\.com)$" {
url.rewrite-once = ( "^/(.*)" => "/%0/$1" )
}
  1. please note, that we have two regular expressions: the one which
  2. $HTTP["host"] is been compared with, and the one of the rewrite rule.
  3. the numbered subexpressions available to build the relative uri are
  4. being prefixed by '%' for subexpressions of the first regular expression
  5. match and by '$' for subexpressions of the second one.
  6. in the case, when the rewrite rule is not included in a conditional
  7. block, only the '$' prefixed variables are available.
  8. subexpression 0 is the whole matching expression.

With mod_redirect
-----------------

Rewrite rules always execute before redirect rules. This is true regardless of the order of module loading or the order of rules in the configuration (lighttpd v1.4.13). However, mod_rewrite provides a mechanism to pass URLs through unmangled: specify "$0" as the rule target.
e.g. ::
url.rewrite-once = (
"^/foo" => "$0",
"^/(.*)" => "/handler/$1"
)
url.redirect = (
"^/foo" => "http://foo.bar/"
)

Workaround for "File name too long" on Windows
----------------------------------------------
While running Lighttpd on Windows you may get ``500 Internal Server Error`` if computed filename is longer than 255 symbols.
In error log it will be ``(response.c.537) file not found ... or so: File name too long /very_looooong_path ->``.
As workaround you can use ``mod_rewrite`` to avoid this error.

::
server.modules += ("mod_rewrite")
url.rewrite-once = ( ".{250,}" => "/toolong.php" )

If error handler is PHP, ``$_SERVER['REQUEST_URI']`` will contain full URI.

Passing / Matching the Query string (GET variables)
---------------------------------------------------

If you wanna pass the Query String (?foo=bar) to the rewrite destination you have to explicitly match it:

::
url.rewrite-once = (
"^/news/([^\?]+)(\?(.*))?" => "/news.php?title=$1&$3"
)

}}}

Updated by dandv over 15 years ago · 37 revisions