![[APACHE DOCUMENTATION]](../images/sub.gif) 
 
      This module provides for documents with Server Side Includes (SSI).
Status: Base
     Source File:
    mod_include.c
     Module Identifier:
    includes_module
This module provides a handler which will process files before they are sent to the client. The processing is controlled by specially formated SGML comments, referred to as elements. These elements allow conditional text, the inclusion other files or programs, as well as the setting and printing of environment variables.
For an introduction to this topic, we also provide a tutorial on Server Side Includes.
See also: Options and AddHandler.
Includes option is set. If
    documents containing server-side include directives are given
    the extension .shtml, the following directives will make Apache
    parse them and assign the resulting document the mime type of
    text/html: 
AddType text/html .shtml AddHandler server-parsed .shtmlThe following directive must be given for the directories containing the shtml files (typically in a
<Directory> section, but this directive is
    also valid .htaccess files if AllowOverride
    Options is set): 
Options +IncludesAlternatively the
XBitHack
    directive can be used to parse normal (text/html)
    files, based on file permissions. 
    For backwards compatibility, documents with mime type
    text/x-server-parsed-html or
    text/x-server-parsed-html3 will also be parsed
    (and the resulting output given the mime type
    text/html).
The value will often be enclosed in double quotes; many commands only allow a single attribute-value pair. Note that the comment terminator (-->) should be preceded by whitespace to ensure that it isn't considered part of an SSI token.<!--#element attribute=value attribute=value ...-->
The allowed elements are:
bytes
          for a count in bytes, or abbrev for a count
          in Kb or Mb as appropriate.strftime(3) library routine when printing
          dates.(none). Any dates printed are subject to the
        currently configured timefmt. Attributes: 
        echo element,
          the default is set to "entity", resulting in entity
          encoding (which is appropriate in the context of a
          block-level HTML element, eg. a paragraph of text). This
          can be changed by adding an encoding
          attribute, which will remain in effect until the next
          encoding attribute is encountered or the
          element ends, whichever comes first. Note that the
          encoding attribute must precede the
          corresponding var attribute to be effective,
          and that only special characters as defined in the
          ISO-8859-1 character encoding will be encoded. This
          encoding process may not have the desired result if a
          different character encoding is in use. Apache 1.3.12 and
          above; previous versions do no encoding.The CGI script is given the PATH_INFO and query string (QUERY_STRING) of the original request from the client; these cannot be specified in the URL path. The include variables will be available to the script in addition to the standard CGI environment.
For example:
<!--#exec cgi="/cgi-bin/example.cgi" -->
            If the script returns a Location: header instead of output, then this will be translated into an HTML anchor.
The include
            virtual element should be
            used in preference to exec cgi. In particular,
            if you need to pass additional arguments to a CGI program,
            using the query string, this cannot be done with exec
            cgi, but can be done with include
            virtual, as shown here:
<!--#include virtual="/cgi-bin/example.cgi?argument=value" -->
          The server will execute the given string using
          /bin/sh. The include variables are available
          to the command, in addition to the usual set of CGI 
          variables.
The use of #include 
        virtual is almost always
        prefered to using either #exec cgi or #exec
        cmd. The former (#include virtual) used the
        standard Apache sub-request mechanism to include files or
        scripts. It is much better tested and maintained.
In addition, on some platforms, like Win32, and on unix
          when using suexec, you cannot pass arguments to a command in 
          an exec directive, or otherwise include spaces in
          the command. Thus, while the following will work under a
          non-suexec configuration on unix, it will not produce the
          desired result under Win32, or when running suexec:
<!--#exec cmd="perl /path/to/perlscript arg1 arg2" -->
          sizefmt format specification.
        Attributes: 
        timefmt format
      specification. The attributes are the same as for the
      fsize command.An attribute defines the location of the document; the inclusion is done for each attribute given to the include command. The valid attributes are:
../, nor can it be an absolute path.
          Therefore, you cannot include files that are outside of the
          document root, or above the current document in the directory
          structure.
          The virtual attribute should always be used
          in preference to this one.The value is a (%-encoded) URL relative to the current document being parsed. The URL cannot contain a scheme or hostname, only a path and an optional query string. If it does not begin with a slash (/) then it is taken to be relative to the current document.
A URL is constructed from the attribute, and the output the server would return if the URL were accessed by the client is included in the parsed output. Thus included files can be nested.
If the specified URL is a CGI program, the program will be executed and its output inserted in place of the directive in the parsed file. You may include a query string in a CGI url:
<!--#include virtual="/cgi-bin/example.cgi?argument=value" -->
           
           include virtual should be used in preference
           to exec cgi to include the output of CGI
           programs into an HTML document.
          
This prints out a listing of all existing variables and
      their values. Starting with Apache 1.3.12, special characters
      are entity encoded (see the echo element for details)
      before being output. There are no attributes.
For example:
<!--#printenv -->
The printenv element is available only in Apache 1.2 and above.
        For example: <!--#set var="category" value="help"
        -->
The set element is available only in Apache 1.2 and above.
echo command, for
    if and elif, and to any program
    invoked by the document. 
    Variable substitution is done within quoted strings in most cases where they may reasonably occur as an argument to an SSI directive. This includes the config, exec, flastmod, fsize, include, and set directives, as well as the arguments to conditional operators. You can insert a literal dollar sign into the string using backslash quoting:
    <!--#if expr="$a = \$test" -->
    If a variable reference needs to be substituted in the middle of a character sequence that might otherwise be considered a valid identifier in its own right, it can be disambiguated by enclosing the reference in braces, à la shell substitution:
    <!--#set var="Zed" value="${REMOTE_HOST}_${REQUEST_METHOD}" -->
    This will result in the Zed variable being set to "X_Y" if REMOTE_HOST is "X" and REQUEST_METHOD is "Y".
EXAMPLE: the below example will print "in foo" if the DOCUMENT_URI is /foo/file.html, "in bar" if it is /bar/file.html and "in neither" otherwise:
    <!--#if expr="\"$DOCUMENT_URI\" = \"/foo/file.html\"" -->
    in foo
    <!--#elif expr="\"$DOCUMENT_URI\" = \"/bar/file.html\"" -->
    in bar
    <!--#else -->
    in neither
    <!--#endif -->
    
    <!--#if expr="test_condition" -->
    <!--#elif expr="test_condition" -->
    <!--#else -->
    <!--#endif -->
    The if element works like an
    if statement in a programming language. The test condition is
    evaluated and if the result is true, then the text until the
    next elif,
    else. or
    endif element is included in the
    output stream.
The elif or
    else statements are be used the
    put text into the output stream if the original test_condition
    was false. These elements are optional.
The endif element ends the
    if element and is required.
test_condition is one of the following:
"=" and "!=" bind more tightly than "&&" and "||". "!" binds most tightly. Thus, the following are equivalent:
    <!--#if expr="$a = test1 && $b = test2" -->
    <!--#if expr="($a = test1) && ($b = test2)" -->
    Anything that's not recognized as a variable or an operator is treated as a string. Strings can also be quoted: 'string'. Unquoted strings can't contain whitespace (blanks and tabs) because it is used to separate tokens such as variables. If multiple strings are found in a row, they are concatenated using blanks. So,
     string1    string2  results in string1 string2
    'string1    string2' results in string1    string2
    XBitHack
    offThe XBitHack directives controls the parsing of ordinary
    html documents. This directive only affects files associated
    with the MIME type text/html. XBitHack can take on
    the following values:
on but also test the group-execute bit.
        If it is set, then set the Last-modified date of the
        returned file to be the last modified time of the file. If
        it is not set, then no last-modified date is sent. Setting
        this bit allows clients and proxies to cache the result of
        the request. 
        Note: you would not want to use this,
        for example, when you #include a CGI that
        produces different output on each hit (or potentially
        depends on the hit).
 
    