mod_setenvifmod_setenvif overviewmod_setenvif module allows to set environment variables if specific parts of request match given regular expressions. These environment variables may be used by other parts of the server to make decisions about which actions to make.
Extended expressions
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| Description: | Sets environment variables conditional on HTTP User-Agent |
| Syntax: | BrowserMatch regex [!]env-variable[=value] [[!]env-variable[=value]] ... [late] |
| Context: | server config, virtual host, directory, .htaccess |
| Module: | mod_setenvif |
BrowserMatch (special case of SetEnvIf directive) allows processing of environment variables depending on the value of User-Agent header.
Example:
BrowserMatch MSIE !javascriptBrowserMatchNoCase
| Description: | Sets environment variables conditional on User-Agent regardless of case |
| Syntax: | BrowserMatchNoCase regex [!]env-variable[=value] [[!]env-variable[=value]] ... [late] |
| Context: | server config, virtual host, directory, .htaccess |
| Module: | mod_setenvif |
BrowserMatchNoCase directive (special case of SetEnvIfNoCase directive) has the same meaning as BrowserMatch directive, the only difference is that it performs case-insensitive matching.
Example:
BrowserMatchNoCase mac platform=macintosh
BrowserMatchNoCase win platform=windowsSetEnvIf
| Description: | Sets environment variables based on attributes of the request |
| Syntax: | SetEnvIf attribute regex [!]env-variable[=value] [[!]env-variable[=value]] ... [late] |
| Context: | server config, virtual host, directory, .htaccess |
| Module: | mod_setenvif |
SetEnvIf directive defines environment variables based on the attributes of the request.
attribute value may be one of the following:
- HTTP request header field, e.g., Host, User-Agent, Referer,
and Accept-Language. Regular expressions are possible.
- One of these request elements:
Remote_Host - hostname (if available) of the client making the request;
Remote_Addr - IP address of the client making the request;
Server_Addr - IP address of the server that received the request;
Request_Method - method name (GET, POST, etc.);
Request_Protocol - name and version of the protocol that served the request (always "HTTP/1.1");
Request_URI - the resource requested by HTTP request; is usually represented by a part of the URL after hosthame and without query string.
The following values are not supported by Apache:
Query_String - the query string requested by HTTP request;
Mime -Content-Typeresponse header value. Note that not only MIME-type may be specified in the value. Please refer to HTTP protocol documentation to get more information.
- 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 SetEnv[If[NoCase]] directives are available for testing in this manner. Earlier means above in current context or in broader context (e.g., server level). Environment variables will be processed only if none of request characteristics matched and regular expression was not used for attribute.
- Server variables (supported only in Helicon Ape; Apache doesn't support this feature).
regex argument represents regular expression. If the regex matches against the attribute, consequent arguments are processed.
The following arguments are used either to assign variable names to be set and values they will obtain or to unset existing variables.
Example:
#the value of varname will be set to 1
varname
#variable will be deleted
!varname
#varname will be assigned 'value'
varname=value$1..$N constructions are also recognized, the values are taken from regex argument.
%{ENV_NAME}e format may be used in the name of environment variables to get the value of existing variables (Apache doesn't support this feature).
Example:
SetEnvIf Host (.*) my-host=$1
BrowserMatch Mozilla/4\.[678] stop-old-stuff="Mozilla4.6-8 isn't allowed on %{my-host}e"
Header set Ban %{stop-old-stuff}e env=stop-old-stuff
Ban header will be created if the client browser is indentified as Mozilla/4.6-8.
late argument allows to set variables after script execution. So the script couldn't see variables created with late argument. The argument is designed to modify environment in dependence with script actions (maybe additional HTTP headers will be added etc.). Apache doesn't support late argument.
If you use Mime argument, it will be processed after script execution because Content-Type header is not accessible earlier.
Simple usage:
#sets object_type variable if jpg image was requested
SetEnvIf Request_URI "\.jpg$" object_type=jpg
#sets ref_var variable if the request refers to somewhere on www.domain.com
SetEnvIf Referer www\.domain\.com ref_varConfigure mod_gzip:
mod_gzip_on yes
SetEnvIf Mime ^text/html gzip=9
SetEnvIf Mime ^image/.* no-gzip
SetEnvIf Mime ^text/plain gzip
SetEnvIfNoCase
| Description: | Sets environment variables based on attributes of the request regardless of case |
| Syntax: | SetEnvIfNoCase attribute regex [!]env-variable[=value] [[!]env-variable[=value]] ... [late] |
| Context: | server config, virtual host, directory, .htaccess |
| Module: | mod_setenvif |
SetEnvIfNoCase directive has the same meaning as SetEnvIf directive, the only difference is that it performs case-insensitive matching.
Example:
#sets site variable if Host header includes sitename.com
SetEnvIfNoCase Host sitename\.com site=sitename