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<modulesynopsis>

<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>
<compatibility>Available in Apache 1.3 and later</compatibility>


<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</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>
<compatibility>Apache 1.2 and
    above (in Apache 1.2 this directive was found in the
    now-obsolete mod_browser module)</compatibility>

<usage>
    <p>The <directive>BrowserMatch</directive> directive defines
    environment variables based on the <code>User-Agent</code> HTTP
    request header field.  The first argument should be a POSIX.2
    extended regular expression (similar to an
    <code>egrep</code>-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</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 value given by
    <code><em>value</em></code>. If a <code>User-Agent</code>
    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.</p>

    <p>For example:</p>
<example>
    BrowserMatch ^Mozilla forms jpeg=yes browser=netscape<br />
    BrowserMatch "^Mozilla/[2-3]" tables agif frames javascript<br />
    BrowserMatch MSIE !javascript<br />
</example>
 
    <p>Note that the regular expression string is
    <strong>case-sensitive</strong>. For case-INsensitive matching,
    see the <directive
    module="mod_setenvif">BrowserMatchNoCase</directive>
    directive.</p>

    <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>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>
<compatibility>Apache 1.2 and
    above (in Apache 1.2 this directive was found in the
    now-obsolete mod_browser module)</compatibility>

<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>
<compatibility>Apache 1.3 and
    above; the Request_Protocol keyword and environment-variable
    matching are only available with 1.3.7 and later</compatibility>

<usage>
    <p>The <directive>SetEnvIf</directive> directive defines environment
    variables based on attributes of the request. These attributes
    can be the values of various HTTP request header fields (see <a
    href="http://www.rfc-editor.org/rfc/rfc2616.txt">RFC2616</a>
    for more information about these), or of other aspects of the
    request, including the following:</p>

    <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>Remote_User</code> - the authenticated username (if
      available)</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 portion of the URL
      following the scheme and host portion</li>
    </ul>

    <p>Some of the more commonly used request header field names
    include <code>Host</code>, <code>User-Agent</code>, and
    <code>Referer</code>.</p>

    <p>If the <em>attribute</em> 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
    <directive>SetEnvIf</directive> directives to test against the result of
    prior matches.</p>

<note>
      <strong>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.</strong>
</note>

    <p><em>attribute</em> may be a regular expression when used to
    match a request header. If <em>attribute</em> is a regular
    expression and it doesn't match any of the request's header
    names, then <em>attribute</em> is not tested against the
    request's environment variable list.</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\.com intra_site_referral<br />
        :<br />
   SetEnvIf object_is_image xbm XBIT_PROCESSING=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.com</code> Web site.</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>
</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>
<compatibility>Apache 1.3 and above</compatibility>

<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>