![[APACHE DOCUMENTATION]](../images/sub.gif)
Apache HTTP Server Version 2.0
Apache Module mod_setenvif
|
Summary
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
Directives
See also
BrowserMatch Directive
|
The BrowserMatch directive defines
environment variables based on the User-Agent HTTP
request header field. The first argument should be a POSIX.2
extended regular expression (similar to an
egrep-style regex). 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 value given by
value. If a User-Agent
string matches more than one entry, they will be merged.
Entries are processed in the order in which they appear, and
later entries can override earlier ones.
For example:
BrowserMatch ^Mozilla forms jpeg=yes browser=netscape
BrowserMatch "^Mozilla/[2-3]" tables agif frames javascript
BrowserMatch MSIE !javascript
Note that the regular expression string is
case-sensitive. For case-INsensitive matching,
see the BrowserMatchNoCase
directive.
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
BrowserMatchNoCase Directive
|
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
SetEnvIf Directive
|
The SetEnvIf directive defines environment
variables based on attributes of the request. These attributes
can be the values of various HTTP request header fields (see RFC2616
for more information about these), or of other aspects of the
request, including the following:
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 portion of the URL following the scheme and host portion
Some of the more commonly used request header field names
include Host, User-Agent, and
Referer.
If the attribute name doesn't match any of the
special keywords, nor any of the request's header field names,
it is tested as the name of an environment variable in the list
of those associated with the request. This allows
SetEnvIf 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.
attribute may be a regular expression when used to match a request header. If attribute is a regular expression and it doesn't match any of the request's header names, then attribute is not tested against the request's environment variable list.
Example:
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].
SetEnvIfNoCase Directive
|
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.
Apache HTTP Server Version 2.0
