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1. Using server side includes.

 
Using server side includes.
I've heard that server side includes (SSI) allow you to dynamically insert content in the middle of a page. This sounds great - how do I do it?

It's easy! Here's how:
  1. First, create your HTML files as usual. [how do I do that?] Server side includes are embedded into the content of a normal html page. [what's html?]

  2. Rename the HTML file that will contain the included content (ie: whatever.html) to end in ".shtml" (ie: whatever.shtml).

    Note that you may have to alter links to that page, as changing the name will break any links made to it. If the parent web page does not have the .shtml extension, server side includes will not work.

  3. Now, add some special commands to the page into which you want to dynamically add content. This page is parsed as usual - as a normal HTML document; the special commands are embedded as SGML comments. A command has the syntax:

         <!--#element attribute=value attribute=value ... -->

    The value will often be enclosed in double quotes, and 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. A single space should be sufficient. Here are some basic elements you may run across:


    The 'config' Element  [back]

    config

    This command controls various aspects of the parsing. The valid attributes are:

    errmsg
    The value is a message that is sent back to the client if an error occurs whilst parsing the document.

    sizefmt
    The value sets the format to be used which displaying the size of a file. Valid values are bytes for a count in bytes, or abbrev for a count in Kb or Mb as appropriate.

    timefmt
    The value is a string to be used by the strftime(3) library routine when printing dates.

    echo
    This command prints one of the include variables, defined below. If the variable is unset, it is printed as (none). Any dates printed are subject to the currently configured 'timefmt' element. The only valid attribute is:

    var
    The value is the name of the variable to print.

    The 'exec' Element  [back]

    exec

    The exec command executes a given shell command or CGI script. The IncludesNOEXEC Option disables this command completely. Its valid attributes are:

    cgi
    The value specifies a (%-encoded) URL relative path to the CGI script. If the path does not begin with a (/), then it is taken to be relative to the current document. The document referenced by this path is invoked as a CGI script, even if the server would not normally recognize it as such. However, the directory containing the script must be enabled for CGI scripts (with ScriptAlias or the ExecCGI Option).

    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.

    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.

    cmd
    The server will execute the given string using /bin/sh. The include variables are available to the command.

    The 'fsize' Element  [back]

    fsize

    This command prints the size of the specified file, subject to the sizefmt format specification. Attributes:

    file
    The value is a path relative to the directory containing the current document being parsed.

    virtual
    The value is a quoted and %-encoded URL-path relative to the current document being parsed. If it does not begin with a slash (/) then it is taken to be relative to the current document.

    The 'flastmod' Element   [back]

    flastmod

    This command prints the last modification date of the specified file, subject to the timefmt format specification. The attributes are the same as for the fsize command.

    The 'include' Element   [back]

    include

    This command inserts the text of another document or file into the parsed file. Any included file is subject to the usual access control. If the directory containing the parsed file has the Option IncludesNOEXEC set, and the including the document would cause a program to be executed, then it will not be included; this prevents the execution of CGI scripts. Otherwise CGI scripts are invoked as normal using the complete URL given in the command, including any query string.

    An attribute defines the location of the document; the inclusion is done for each attribute given to the include command. The valid attributes are:

    file
    The value is a path relative to the directory containing the current document being parsed. It cannot contain ../, nor can it be an absolute path. The virtual attribute should always be used in preference to this one.

    virtual
    The value is a quoted and %-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.

    The 'printenv' Element  [back]

    printenv

    This prints out a listing of all existing variables and their values. No attributes.

         For example: <!--#printenv -->

    The 'set' Element  [back]

    set

    This sets the value of a variable. Attributes:

    var
    The name of the variable to set.

    value
    The value to give a variable.
         For example: <!--#set var="category" value="help" -->

    Include Variables  [back]

    In addition to the variables in the standard CGI environment, these are available for the echo command, for if and elif, and to any program invoked by the document.

    DATE_GMT

    The current date in Greenwich Mean Time.

    DATE_LOCAL

    The current date in the local time zone.

    DOCUMENT_NAME

    The filename (excluding directories) of the document requested by the user.

    DOCUMENT_URI

    The (%-decoded) URL path of the document requested by the user. Note that in the case of nested include files, this is not then URL for the current document.

    LAST_MODIFIED

    The last modification date of the document requested by the user.

    Variable Substitution  [back]

    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, 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 -->


    Flow Control Elements  [back]

    These are available in Apache 1.2 and above (which our servers run). The basic flow control elements are:

         <!--#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:

    string

    true if string is not empty

    string1 = string2
    string1 != string2

    Compare string1 with string 2. If string2 has the form /string/ than it is compared as a regular expression. Regular expressions have the same syntax as those found in the Unix egrep command.

    ( test_condition )

    true if test_condition is true

    ! test_condition

    true if test_condition is false

    test_condition1 && test_condition2

    true if both test_condition1 and test_condition2 are true

    test_condition1 || test_condition2

    true if either test_condition1 or test_condition2 is true

    "=" 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

Last updated: Jul 26, 2004.

User Post (2002-06-17 13:14:30 by josh)
for those of you who found this article confusing the attached will include a file (presuming it's called header.inc of course!!)
&lt;!--#include file="header.inc" --&gt;
User Post (2001-07-31 13:31:43 by goeller)
<b>Comments and Blank Spaces</b>
<br>

Were you mistaking the <i>comment terminator</i> for the comment tag?<br><br>

This part:<br><br> <b>--></b><br><br> is the <i>comment terminator</i> described in the article.<br><br>

The space goes before the comment terminator, like so:<br><br>

<b> blah &nbsp&nbsp&nbsp&nbsp --></b><br><br>

If you put a space before the end of the <i>comment tag</i>, that is, between the dashes and the >, then the comment no longer has the proper syntax for a comment, and it won't work.<br><br>

The terminology is easy to confuse --- thanks for pointing this out.<br><br>




User Post (2005-12-13 10:27:21 by askmartin)
Using SSI & PHP Together - but it CAN BE DONE on DH! I use Dreamweaver and build my sites with templates. To make a PHP page honor an include, do the following:
In your template, place the appropriate PHP include statement where you would normally place a DH-compatible SSI:

<?php include('../includes/myfile.php'); ?>

Don't Worry that Dreamweaver does not recognize the PHP code properly while editing the template.

You MUST use 'php' for the file extension and nothing else works!!!

If you have other SHTML files using the same include file, just code the normal include and use the same 'php' extension (as shown below). That way you only have ONE include file and it works for both PHP and SHTML page types.

<!--#include virtual="/includes/myfile.php" -->
User Post (2005-10-18 09:38:16 by michaelriot)
can I include pages off the server...

see http://www.smarterscripts.com/executer/
User Post (2005-07-25 06:21:37 by bigair)
No space at end "--> not " --> or it will not work.
User Post (2004-05-30 18:50:54 by obiwan1129)
I am using an SSI to make my page take 10 secnds to load. I am using the command below in my shtml file but it doesn't seem to be working.

Any thoughts?

<!--#exec cmd="sleep 10" -->
User Post (2004-03-24 05:45:48 by jayce)
I had some trouble with the organization of the article, like is "echo" its own command or part of the "config" command? And what's the "var" for? In my specific example, to get the HTTP referrer (or referer, depending on if you're an SSI junkie or JavaScript junkie) I used:

<!--#echo var="HTTP_REFERER" -->

or

&lt;!--#echo var="HTTP_REFERER" --&gt;

(I don't remember if comments get HTML parsed ... the one with the angle-brackets is the right one.)
User Post (2003-12-17 12:53:35 by b1zdin93)
I have added SSI to point to a footer. I want to use the same footer for all my pages. I have put the footer in the root directory to test, and changed the path location in the include command statement, but I get an error, unless the include file is in the same directory as the parent file.

Does anyone know the correct syntax so that I can point to the same footer file for any pages? I tried using the url (eg 'http://www.website.com/footer.inc' ) but still get an error.)
thanks
User Post (2003-04-17 08:52:08 by chillicothe2003)
Can you include a page off the server, say <!--#include file="http://www.yahoo.com" --> I can't get it to work
User Post (2001-08-13 08:26:49 by dobie1)
I'm just trying to get a SSI random image displayer to work do I really need all those variables?
User Post (2001-05-04 22:10:22 by insider1)
this tutorial specifically says to add a space before ending the comment tag but the only way i can get my ssi tag to work is if i remove these spaces... what gives?