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<?xml-stylesheet type="text/xsl" href="/style/manual.en.xsl"?>

<modulesynopsis metafile="mod_setenvif.xml.meta">

<name>mod_setenvif</name>

<description>Allows the setting of environment variables based

on characteristics of the request</description>

<status>Base</status>

<sourcefile>mod_setenvif.c</sourcefile>

<identifier>setenvif_module</identifier>

<summary>

<p>The <module>mod_setenvif</module> 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.</p>

<p>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 <code>netscape</code> if the

browser is mozilla but not MSIE.</p>

<example>

BrowserMatch ^Mozilla netscape<br />

BrowserMatch MSIE !netscape<br />

</example>

</summary>

<seealso><a href="/env.html">Environment Variables in Apache HTTP Server</a></seealso>

<directivesynopsis>

<name>BrowserMatch</name>

<description>Sets environment variables conditional on HTTP User-Agent

</description>

<syntax>BrowserMatch <em>regex [!]env-variable</em>[=<em>value</em>]

[[!]<em>env-variable</em>[=<em>value</em>]] ...</syntax>

<contextlist><context>server config</context>

<context>virtual host</context><context>directory</context>

<context>.htaccess</context></contextlist>

<override>FileInfo</override>

<usage>

<p>The <directive>BrowserMatch</directive> is a special cases of the

<directive module="mod_setenvif">SetEnvIf</directive> directive that

sets environment variables conditional on the

<code>User-Agent</code> HTTP request header. The following two

lines have the same effect:</p>

<example>

BrowserMatchNoCase Robot is_a_robot<br />

SetEnvIfNoCase User-Agent Robot is_a_robot<br />

</example>

<p>Some additional examples:</p>

<example>

BrowserMatch ^Mozilla forms jpeg=yes browser=netscape<br />

BrowserMatch "^Mozilla/[2-3]" tables agif frames javascript<br />

BrowserMatch MSIE !javascript<br />

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>BrowserMatchNoCase</name>

<description>Sets environment variables conditional on User-Agent without

respect to case</description>

<syntax>BrowserMatchNoCase <em>regex [!]env-variable</em>[=<em>value</em>]

[[!]<em>env-variable</em>[=<em>value</em>]] ...</syntax>

<contextlist><context>server config</context>

<context>virtual host</context><context>directory</context>

<context>.htaccess</context></contextlist>

<override>FileInfo</override>

<usage>

<p>The <directive>BrowserMatchNoCase</directive> directive is

semantically identical to the <directive

module="mod_setenvif">BrowserMatch</directive> directive.

However, it provides for case-insensitive matching. For

example:</p>

<example>

BrowserMatchNoCase mac platform=macintosh<br />

BrowserMatchNoCase win platform=windows<br />

</example>

<p>The <directive>BrowserMatch</directive> and

<directive>BrowserMatchNoCase</directive> directives are special cases of

the <directive module="mod_setenvif">SetEnvIf</directive> and <directive

module="mod_setenvif">SetEnvIfNoCase</directive>

directives. The following two lines have the same effect:</p>

<example>

BrowserMatchNoCase Robot is_a_robot<br />

SetEnvIfNoCase User-Agent Robot is_a_robot<br />

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SetEnvIf</name>

<description>Sets environment variables based on attributes of the request

</description>

<syntax>SetEnvIf <em>attribute

regex [!]env-variable</em>[=<em>value</em>]

[[!]<em>env-variable</em>[=<em>value</em>]] ...</syntax>

<contextlist><context>server config</context>

<context>virtual host</context><context>directory</context>

<context>.htaccess</context></contextlist>

<override>FileInfo</override>

<usage>

<p>The <directive>SetEnvIf</directive> directive defines

environment variables based on attributes of the request. The

<em>attribute</em> specified in the first argument can be one of four

things:</p>

<ol>

<li>An HTTP request header field (see <a

href="http://www.rfc-editor.org/rfc/rfc2616.txt">RFC2616</a>

for more information about these); for example: <code>Host</code>,

<code>User-Agent</code>, <code>Referer</code>, and

<code>Accept-Language</code>. A regular expression may be

used to specify a set of request headers.</li>

<li>One of the following aspects of the request:

<ul>

<li><code>Remote_Host</code> - the hostname (if available) of

the client making the request</li>

<li><code>Remote_Addr</code> - the IP address of the client

making the request</li>

<li><code>Server_Addr</code> - the IP address of the server

on which the request was received (only with versions later

than 2.0.43)</li>

<li><code>Request_Method</code> - the name of the method

being used (<code>GET</code>, <code>POST</code>, <em>et

cetera</em>)</li>

<li><code>Request_Protocol</code> - the name and version of

the protocol with which the request was made (<em>e.g.</em>,

"HTTP/0.9", "HTTP/1.1", <em>etc.</em>)</li>

<li><code>Request_URI</code> - the resource requested on the HTTP

request line -- generally the portion of the URL

following the scheme and host portion without the query string. See

the <directive module="mod_rewrite">RewriteCond</directive>

directive of <module>mod_rewrite</module> for extra information on

how to match your query string.</li>

</ul>

</li>

<li>The name of an environment variable in the list of those

associated with the request. This allows

<directive>SetEnvIf</directive> directives to test against the result

of prior matches. Only those environment variables defined by earlier

<code>SetEnvIf[NoCase]</code> 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 <em>attribute</em>.</li>

<li>

A reference to an extension of an SSL client certificate, located by

its object id <em>oid</em>.

If a non-SSL request, or in absense of the configured <em>oid</em>,

no variable will be set. If the <em>oid</em> is found multiple times,

the individual strings will be concatenated, separated by a comma <code>','</code>.

The <em>oid</em> should reference a string-valued extension.

</li>

</ol>

<p>The second argument (<em>regex</em>) is a <glossary

ref="regex">regular expression</glossary>. If the <em>regex</em>

matches against the <em>attribute</em>, then the remainder of the

arguments are evaluated.</p>

<p>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</p>

<ol>

<li><code><em>varname</em></code>, or</li>

<li><code>!<em>varname</em></code>, or</li>

<li><code><em>varname</em>=<em>value</em></code></li>

</ol>

<p>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

<code><em>value</em></code>. Since version 2.0.51, Apache httpd will

recognize occurrences of <code>$1</code>..<code>$9</code> within

<var>value</var> and replace them by parenthesized subexpressions

of <var>regex</var>.</p>

<example>

<title>Example:</title>

SetEnvIf Request_URI "\.gif$" object_is_image=gif<br />

SetEnvIf Request_URI "\.jpg$" object_is_image=jpg<br />

SetEnvIf Request_URI "\.xbm$" object_is_image=xbm<br />

:<br />

SetEnvIf Referer www\.mydomain\.example\.com intra_site_referral<br />

:<br />

SetEnvIf object_is_image xbm XBIT_PROCESSING=1<br />

:<br />

SetEnvIf OID("2.16.840.1.113730.1.13") "(.*)" NetscapeComment=$1<br />

:<br />

SetEnvIf ^TS* ^[a-z].* HAVE_TS<br />

</example>

<p>The first three will set the environment variable

<code>object_is_image</code> if the request was for an image

file, and the fourth sets <code>intra_site_referral</code> if

the referring page was somewhere on the

<code>www.mydomain.example.com</code> Web site.</p>

<p>The sixth example will set the <code>NetscapeComment</code>

environment variable to the string found in the corresponding

SSL client certificate field (if found).</p>

<p>The last example will set environment variable

<code>HAVE_TS</code> if the request contains any headers that

begin with "TS" whose values begins with any character in the

set [a-z].</p>

</usage>

<seealso><a href="/env.html">Environment Variables in Apache HTTP Server</a>,

for additional examples.

</seealso>

</directivesynopsis>

<directivesynopsis>

<name>SetEnvIfExpr</name>

<description>Sets environment variables based on an ap_expr expression</description>

<syntax>SetEnvIfExpr <em>expr

[!]env-variable</em>[=<em>value</em>]

[[!]<em>env-variable</em>[=<em>value</em>]] ...</syntax>

<contextlist><context>server config</context>

<context>virtual host</context><context>directory</context>

<context>.htaccess</context></contextlist>

<override>FileInfo</override>

<usage>

<p>The <directive>SetEnvIfExpr</directive> directive defines

environment variables based on an <directive type="section">If</directive>

<code>ap_expr</code>. These expressions will be evaluated at runtime,

and applied <em>env-variable</em> in the same fashion as <directive

>SetEnvIf</directive>.</p>

<example>

SetEnvIfExpr "tolower(req('X-Sendfile')) == 'd:\images\very_big.iso')" iso_delivered

</example>

<p>This would set the environment variable <code>iso_delivered</code>

every time our application attempts to send it via <code>X-Sendfile</code></p>

<p>A more useful example would be to set the variable rfc1918 if the

remote IP address is a private address according to RFC 1918:</p>

<example>

SetEnvIfExpr "-R '10.0.0.0/8' || -R '172.16.0.0/12' || -R '192.168.0.0/16'" rfc1918

</example>

</usage>

<seealso><a href="/expr.html">Expressions in Apache HTTP Server</a>,

for a complete reference and more examples.</seealso>

<seealso><directive type="section">If</directive> can be used to achive similar

results.</seealso>

<seealso><module>mod_filter</module></seealso>

</directivesynopsis>

<directivesynopsis>

<name>SetEnvIfNoCase</name>

<description>Sets environment variables based on attributes of the request

without respect to case</description>

<syntax>SetEnvIfNoCase <em>attribute regex

[!]env-variable</em>[=<em>value</em>]

[[!]<em>env-variable</em>[=<em>value</em>]] ...</syntax>

<contextlist><context>server config</context>

<context>virtual host</context><context>directory</context>

<context>.htaccess</context></contextlist>

<override>FileInfo</override>

<usage>

<p>The <directive>SetEnvIfNoCase</directive> is semantically identical to

the <directive module="mod_setenvif">SetEnvIf</directive> directive,

and differs only in that the regular expression matching is

performed in a case-insensitive manner. For example:</p>

<example>

SetEnvIfNoCase Host Apache\.Org site=apache

</example>

<p>This will cause the <code>site</code> environment variable

to be set to "<code>apache</code>" if the HTTP request header

field <code>Host:</code> was included and contained

<code>Apache.Org</code>, <code>apache.org</code>, or any other

combination.</p>

</usage>

</directivesynopsis>

</modulesynopsis>