Apache HTTP Server Version 2.0
Description: | Allows the setting of environment variables based on characteristics of the request |
---|---|
Status: | Base |
Module Identifier: | setenvif_module |
Source File: | mod_setenvif.c |
The mod_setenvif
module allows you to set
environment variables according to whether different aspects of
the request match regular expressions you specify. These
environment variables can be used by other parts of the server
to make decisions about actions to be taken.
The directives are considered in the order they appear in
the configuration files. So more complex sequences can be used,
such as this example, which sets netscape
if the
browser is mozilla but not MSIE.
BrowserMatch ^Mozilla netscape
BrowserMatch MSIE !netscape
Description: | Sets environment variables conditional on HTTP User-Agent |
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Syntax: | BrowserMatch regex [!]env-variable[=value] [[!]env-variable[=value]] ... |
Context: | server config, virtual host, directory, .htaccess |
Override: | FileInfo |
Status: | Base |
Module: | mod_setenvif |
The BrowserMatch
is a special cases of the
SetEnvIf
directive that
sets environment variables conditional on the
User-Agent
HTTP request header. The following two
lines have the same effect:
BrowserMatchNoCase Robot is_a_robot
SetEnvIfNoCase User-Agent Robot is_a_robot
Some additional examples:
BrowserMatch ^Mozilla forms jpeg=yes browser=netscape
BrowserMatch "^Mozilla/[2-3]" tables agif frames javascript
BrowserMatch MSIE !javascript
Description: | Sets environment variables conditional on User-Agent without respect to case |
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Syntax: | BrowserMatchNoCase regex [!]env-variable[=value] [[!]env-variable[=value]] ... |
Context: | server config, virtual host, directory, .htaccess |
Override: | FileInfo |
Status: | Base |
Module: | mod_setenvif |
Compatibility: | Apache 1.2 and above (in Apache 1.2 this directive was found in the now-obsolete mod_browser module) |
The BrowserMatchNoCase
directive is
semantically identical to the BrowserMatch
directive.
However, it provides for case-insensitive matching. For
example:
BrowserMatchNoCase mac platform=macintosh
BrowserMatchNoCase win platform=windows
The BrowserMatch
and
BrowserMatchNoCase
directives are special cases of
the SetEnvIf
and SetEnvIfNoCase
directives. The following two lines have the same effect:
BrowserMatchNoCase Robot is_a_robot
SetEnvIfNoCase User-Agent Robot is_a_robot
Description: | Sets environment variables based on attributes of the request |
---|---|
Syntax: | SetEnvIf attribute regex [!]env-variable[=value] [[!]env-variable[=value]] ... |
Context: | server config, virtual host, directory, .htaccess |
Override: | FileInfo |
Status: | Base |
Module: | mod_setenvif |
The SetEnvIf
directive defines
environment variables based on attributes of the request. The
attribute specified in the first argument can be one of three
things:
Host
,
User-Agent
, Referer
, and
Accept-Language
. A regular expression may be
used to specify a set of request headers.Remote_Host
- the hostname (if available) of
the client making the requestRemote_Addr
- the IP address of the client
making the requestRemote_User
- the authenticated username (if
available)Request_Method
- the name of the method
being used (GET
, POST
, et
cetera)Request_Protocol
- the name and version of
the protocol with which the request was made (e.g.,
"HTTP/0.9", "HTTP/1.1", etc.)Request_URI
- the resource requested on the HTTP
request line -- generally the portion of the URL
following the scheme and host portion without the query stringSetEnvIf
directives to test against the result
of prior matches. Only those environment variables defined by earlier
SetEnvIf[NoCase]
directives are available for testing in
this manner. 'Earlier' means that they were defined at a broader scope
(such as server-wide) or previously in the current directive's scope.
Environment variables will be considered only if there was no match
among request characteristics and a regular expression was not
used for the attribute.The second argument (regex) is a Perl compatible regular expression. This is similar to a POSIX.2 egrep-style regular expression. If the regex matches against the attribute, then the remainder of the arguments are evaluated.
The rest of the arguments give the names of variables to set, and optionally values to which they should be set. These take the form of
varname
, or!varname
, orvarname=value
In the first form, the value will be set to "1". The second
will remove the given variable if already defined, and the
third will set the variable to the literal value given by
value
.
SetEnvIf Request_URI "\.gif$" object_is_image=gif
SetEnvIf Request_URI "\.jpg$" object_is_image=jpg
SetEnvIf Request_URI "\.xbm$" object_is_image=xbm
:
SetEnvIf Referer www\.mydomain\.com intra_site_referral
:
SetEnvIf object_is_image xbm XBIT_PROCESSING=1
:
SetEnvIf ^TS* ^[a-z].* HAVE_TS
The first three will set the environment variable
object_is_image
if the request was for an image
file, and the fourth sets intra_site_referral
if
the referring page was somewhere on the
www.mydomain.com
Web site.
The last example will set environment variable
HAVE_TS
if the request contains any headers that
begin with "TS" whose values begins with any character in the
set [a-z].
Description: | Sets environment variables based on attributes of the request without respect to case |
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Syntax: | SetEnvIfNoCase attribute regex [!]env-variable[=value] [[!]env-variable[=value]] ... |
Context: | server config, virtual host, directory, .htaccess |
Override: | FileInfo |
Status: | Base |
Module: | mod_setenvif |
Compatibility: | Apache 1.3 and above |
The SetEnvIfNoCase
is semantically identical to
the SetEnvIf
directive,
and differs only in that the regular expression matching is
performed in a case-insensitive manner. For example:
SetEnvIfNoCase Host Apache\.Org site=apache
This will cause the site
environment variable
to be set to "apache
" if the HTTP request header
field Host:
was included and contained
Apache.Org
, apache.org
, or any other
combination.