Ta-daah! The documentation for mod_setenvif, which defines the

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  <H1 ALIGN="CENTER">Module mod_setenvif</H1>

  <P>

  This module is contained in the <SAMP>mod_setenvif.c</SAMP> file, and

  <STRONG>is</STRONG> compiled in by default. It provides for

  the ability to set environment variables based upon attributes of the

  request.

  </P>

  <H2>Summary</H2>

  <P>

  The <SAMP>mod_setenvif</SAMP> module allows you to set environment

  variables according to whether different aspects of the request match

  regular expressions you specify.  These envariables can be used by

  other parts of the server to make decisions about actions to be taken.

  </P>

  <H2>Directives</H2>

  <UL>

   <LI><A HREF="#BrowserMatch">BrowserMatch</A>

   </LI>

   <LI><A HREF="#BrowserMatchNoCase">BrowserMatchNoCase</A>

   </LI>

   <LI><A HREF="#SetEnvIf">SetEnvIf</A>

   </LI>

   <LI><A HREF="#SetEnvIfNoCase">SetEnvIfNoCase</A>

   </LI>

  </UL>

  <HR> <!-- the HR is part of the directive description -->

  <H2><A NAME="BrowserMatch">The <SAMP>BrowserMatch</SAMP> Directive</A></H2>

  <P>

  <STRONG>Syntax:</STRONG> BrowserMatch <EM>regex envar[=value] [...]</EM>

  <BR>

  <STRONG>Default:</STRONG> <EM>none</EM>

  <BR>

  <STRONG>Context:</STRONG> server config

  <BR>

  <STRONG>Override:</STRONG> <EM>none</EM>

  <BR>

  <STRONG>Status:</STRONG> Base

  <BR>

  <STRONG>Module:</STRONG> mod_setenvif

  <BR>

  <STRONG>Compatibility:</STRONG> Apache 1.2 and above

  </P>

  <P>

  The BrowserMatch directive defines environment variables based on the

  <SAMP>User-Agent</SAMP> HTTP request header field. The first argument

  should be a POSIX.2 extended regular expression (similar to an

  <SAMP>egrep</SAMP>-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><SAMP><EM>varname</EM></SAMP>, or

   </LI>

   <LI><SAMP>!<EM>varname</EM></SAMP>, or

   </LI>

   <LI><SAMP><EM>varname</EM>=<EM>value</EM></SAMP>

   </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 <SAMP><EM>value</EM></SAMP>. If a

  <SAMP>User-Agent</SAMP> 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>

  <PRE>

    BrowserMatch ^Mozilla forms jpeg=yes browser=netscape

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

    BrowserMatch MSIE !javascript

  </PRE>

  <P>

  Note that the regular expression string is

  <STRONG>case-sensitive</STRONG>.  For cane-INsensitive matching, see

  the

  <A

   HREF="#BrowserMatchNoCase"

  ><SAMP>BrowserMatchNoCase</SAMP></A>

  directive.

  </P>

  <P>

  The <SAMP>BrowserMatch</SAMP> and <SAMP>BrowserMatchNoCase</SAMP>

  directives are special cases of the

  <A

   HREF="#SetEnvIf"

  ><SAMP>SetEnvIf</SAMP></A>

  and

  <A

   HREF="#SetEnvIfNoCase"

  ><SAMP>SetEnvIfNoCase</SAMP></A>

  directives.  The following two lines have the same effect:

  </P>

  <PRE>

   BrowserMatchNoCase Robot is_a_robot

   SetEnvIfNoCase User-Agent Robot is_a_robot

  </PRE>

  <HR> <!-- the HR is part of the directive description -->

  <H2>

   <A NAME="BrowserMatchNoCase">

    The <SAMP>BrowserMatchNoCase</SAMP> Directive

   </A>

  </H2>

  <P>

  <STRONG>Syntax:</STRONG> BrowserMatchNoCase <EM>regex envar[=value] [...]</EM>

  <BR>

  <STRONG>Default:</STRONG> <EM>none</EM>

  <BR>

  <STRONG>Context:</STRONG> server config

  <BR>

  <STRONG>Override:</STRONG> <EM>none</EM>

  <BR>

  <STRONG>Status:</STRONG> Base

  <BR>

  <STRONG>Module:</STRONG> mod_setenvif

  <BR>

  <STRONG>Compatibility:</STRONG> Apache 1.2 and above

  </P>

  <P>

  The <SAMP>BrowserMatchNoCase</SAMP> directive is semantically identical to

  the

  <A

   HREF="#BrowserMatch"

  ><SAMP>BrowserMatch</SAMP></A>

  directive. However, it provides for case-insensitive matching. For

  example:

  </P>

  <PRE>

    BrowserMatchNoCase mac platform=macintosh

    BrowserMatchNoCase win platform=windows

  </PRE>

  <P>

  The <SAMP>BrowserMatch</SAMP> and <SAMP>BrowserMatchNoCase</SAMP>

  directives are special cases of the

  <A

   HREF="#SetEnvIf"

  ><SAMP>SetEnvIf</SAMP></A>

  and

  <A

   HREF="#SetEnvIfNoCase"

  ><SAMP>SetEnvIfNoCase</SAMP></A>

  directives.  The following two lines have the same effect:

  </P>

  <PRE>

   BrowserMatchNoCase Robot is_a_robot

   SetEnvIfNoCase User-Agent Robot is_a_robot

  </PRE>

  <HR> <!-- the HR is part of the directive description -->

  <H2>

   <A NAME="SetEnvIf">

    The <SAMP>SetEnvIf</SAMP> Directive

   </A>

  </H2>

  <P>

  <STRONG>Syntax:</STRONG> SetEnvIf <EM> attribute regex envar[=value] [...]</EM>

  <BR>

  <STRONG>Default:</STRONG> <EM>none</EM>

  <BR>

  <STRONG>Context:</STRONG> server config

  <BR>

  <STRONG>Override:</STRONG> <EM>none</EM>

  <BR>

  <STRONG>Status:</STRONG> Base

  <BR>

  <STRONG>Module:</STRONG> mod_setenvif

  <BR>

  <STRONG>Compatibility:</STRONG> Apache 1.3 and above

  </P>

  <P>

  The <SAMP>SetEnvIf</SAMP> 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://ds.internic.net/rfc/rfc2068.txt"

  >RFC2068</A>

  for more information about these), or of other aspects of the request,

  including the following:

  </P>

  <UL>

   <LI><SAMP>Remote_Host</SAMP> - the hostname (if available) of the

    client making the request

   </LI>

   <LI><SAMP>Remote_Addr</SAMP> - the IP address of the client making

    the request

   </LI>

   <LI><SAMP>Remote_User</SAMP> - the authenticated username (if

    available)

   </LI>

   <LI><SAMP>Request_Method</SAMP> - the name of the method being used

    (<SAMP>GET</SAMP>, <SAMP>POST</SAMP>, <EM>et cetera</EM>)

   </LI>

   <LI><SAMP>Request_URI</SAMP> - 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

  <SAMP>Host</SAMP>, <SAMP>User-Agent</SAMP>, and <SAMP>Referer</SAMP>.

  </P>

  <P>

  Example:

  </P>

  <PRE>

   SetEnvIf Request_URI "\.(gif)|(jpg)|(xbm)$" object_is_image

   SetEnvIf Referer www\.mydomain\.com intra_site_referral

  </PRE>

  <P>

  The first will set the envariable <SAMP>object_is_image</SAMP> if the

  request was for an image file, and the second sets

  <SAMP>intra_site_referral</SAMP> if the referring page was somewhere

  on the <SAMP>www.mydomain.com</SAMP> Web site.

  </P>

  <HR> <!-- the HR is part of the directive description -->

  <H2>

   <A NAME="SetEnvIfNoCase">

    The <SAMP>SetEnvIfNoCase</SAMP> Directive

   </A>

  </H2>

  <P>

  <STRONG>Syntax:</STRONG> SetEnvIfNoCase

   <EM> attribute regex envar[=value] [...]</EM>

  <BR>

  <STRONG>Default:</STRONG> <EM>none</EM>

  <BR>

  <STRONG>Context:</STRONG> server config

  <BR>

  <STRONG>Override:</STRONG> <EM>none</EM>

  <BR>

  <STRONG>Status:</STRONG> Base

  <BR>

  <STRONG>Module:</STRONG> mod_setenvif

  <BR>

  <STRONG>Compatibility:</STRONG> Apache 1.3 and above

  </P>

  <P>

  The <SAMP>SetEnvIfNoCase</SAMP> is semantically identical to the

  <A

   HREF="#SetEnvIf"

  ><SAMP>SetEnvIf</SAMP></A>

  directive, and differs only in that the regular expression matching is

  performed in a case-insensitive manner. For example:

  </P>

  <PRE>

   SetEnvIfNoCase Host Apache\.Org site=apache

  </PRE>

  <P>

  This will cause the <SAMP>site</SAMP> envariable to be set to

  &quot;<SAMP>apache</SAMP>&quot; if the HTTP request header field

  <SAMP>Host:</SAMP> was included and contained <SAMP>Apache.Org</SAMP>,

  <SAMP>apache.org</SAMP>, or any other combination.

  </P>

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