FAQ - Server Side Includes

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FAQ - Domain Names
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FAQ - CGI Scripts

  1. What are Server-Side Includes?
  2. How do I use SSI?
  3. What directives are available?
  4. What extended SSI elements are available?
  5. What SSI environment variables available?
  6. What CGI environment variables can I use with SSI?
  7. Where can I get more information about Server-Side Includes?


1. What are server side includes?

Server-side includes (SSIs) are simple, HTML-embedded directives that instruct the web server to include data in the HTML document. As a shorthand alternative to CGI, server-side includes can be handy.

2. How do I use SSI?

First you must create a page with a .shtm or .shtml extension! Then SSI is easily implemented into your web page by using the following syntax or directives:

<!--#directive parameter="value"-->

Directives can have more than one parameter, and multiple parameters are separated by white space.

3. What directives are available?

The valid SSI directives are as follows:


Syntax: echo var="environment-variable"

Echo inserts the value of one or more SSI environment variables.


Syntax: include file|virtual="path"

The include directive inserts the text of another document, specified either as a file or a virtual file. Path must be relative to the current document in the case of a file, or it can be a virtual path. For example:

<!--#include file="sample.html"-->
<!--#include virtual="/virtual/sample.html"-->


Syntax: fsize file="path"

The fsize directive inserts the size of the file specified by path, in bytes. For example:

This file is <!--#fsize file="example.ps"--> bytes.


Syntax: flastmod file="path"

Similar to fsize, flastmod inserts the modification date for the file specified by path. For example:

This file was last modified on <!--#flastmod file="example.html"-->.


Syntax: config errmsg|sizefmt|timefmt="string"

You can use the config directive to modify the default SSI behavior. The parameters are as follows:

errmsg: Sets the default error message. For example:

<!--#config errmsg="Error: Try again."-->

sizefmt: Sets the format for file size data returned by the fsize directive. The string for this parameter is either "bytes" for file sizes in bytes, or "abbrev" for file sizes rounded to the nearest kilobyte. For example:

<!--#config sizefmt="abbrev"-->

timefmt: Sets the format for dates and times returned by the flastmod directive and the DATE_LOCAL and DATE_GMT variables.

The possible values for this parameter are as follows:

Format Code Description
%a Abbreviated day of the week, such as "Sun" for Sunday
%A Unabbreviated day of the week
%b Abbreviated month, such as "Jan" for January
%B Unabbreviated month
%d Two-digit, numerical day of the month, such as "01" .
%D Numerical month, day, and year, such as "01/24/97"
%e Numerical day, such as "1"
%H 24-hour clock hour, such as "17"
%I 12-hour clock hour, such as "11"
%j Numerical day of the year, such as "278"
%m Numerical month, such as "11"
%M Minutes, such as "08"
%p am or pm
%r Time, such as "08:23:17 am"
%S Seconds, such as "56"
%T 24-hour time, such as "23:54:56"
%U Week of the year, such as "47"
%w Numerical day of the week, such as "0" for Sunday and "7" for Saturday
%y Year of the current century, such as "97"
%z Abbreviated time zone, such as "PST"
skip=n Skips the next n rules in a sequence if the current rule matches
S=n Same as "skip"
env=VARIABLE:VALUE Sets the environment variable VARIABLE to the value VALUE
E=VARIABLE:VALUE Same as "env"


Syntax: printenv

This directive prints a complete list of all existing SSI variables and their values. It has no attributes. For example:



Syntax: set var="variable" value="value"

This directive sets the value of an environment variable. For example:

<!--#set var="country" value="United States"-->

4. What extended SSI elements are available?

Our server implements Extended SSI, which includes flow control elements much like the ones used in
programming languages. With flow control, you can create more sophisticated SSI scripts.

There are four flow control elements:

<!--#if expr="test-condition"-->
<!--#elif expr="test-condition"-->

The test-condition is one of the following:

Test Condition Description
string True if the string is not empty
sring1=string2 True if string1 matches string2
string1!=string2 True if string1 does not match string2
(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

5. What SSI environment variables available?


The filename of the current HTML document. For example:

This file is called <!--#echo var="DOCUMENT_NAME"-->.


The URL of the current file. For example:

This document is located at <!--#echo var="DOCUMENT_URL"-->.


An unencoded query string whose metacharacters are escaped with a backslash (\).


The local date and time. For example:

Here in San Diego, it is now <!--#echo var="DATE_LOCAL"-->.


The current Greenwich Mean Time. For example:

The current time is <!--#echo var="DATE_GMT"--> GMT.


The date and time when the current file was last modified. For example:

I last modified this page on <!--#echo var="LAST_MODIFIED"-->.

6. What CGI environment variables can I use with SSI?


The name and version number of the server software


The host being addressed in this request, which may be the main host or a virtual host, either as a fully-qualified domain name or an IP address


The same as SERVER_NAME

HTTP_ACCEPT=MIME-type[, MIME-type, MIME-type . . .]

One or more MIME types that the client can accept

HTTP_USER_AGENT=name/version (platform)

The name, version number, and platform of the client software


The hostname or IP number of the client host or proxy server that originated the request


The client-side port number that originated the request


The IP number of the client host


The remote username, if the script is subject to basic authentication


The remote username as supplied by identd, if available


The protocol and version number used to send the request, which Stronghold also uses in its response in order to ensure compatibility with the client


The method used in this request, such as GET or POST


The authentication method used in this request, if any


The MIME type of any data attached to the request header


The size, in bytes, of any data attached to the request header


The URI of the requested script


The absolute path to the requested script


The URI of the requested script


The URL of the requested script


The query-string for this transaction, embedded in the requested URL

7. Where can I get more information about Server-Side Includes?

More information on Server-Side Includes can be found at http://hoohoo.ncsa.uiuc.edu/docs/tutorials/includes.html