A: SSI works in conjunction with a web page usually with the .shtml extension. The .shtml extension tells the server to do something different with the web page. When you append the .html or .htm extension, this tells the server to "read" the page only. The .shtml extension tells the server to "Execute" the page, in addition to just reading it. So, why would you want to execute the page? There are various commands you can program into a web page, which the server will look for and parse when the file is called as .shtml. In many cases, this mode is used in conjunction with Server Side Include (SSI) tags, to call a CGI script. For example, you have a visitor counter script, and we'll call it count.cgi. Every time someone visits your website, you want the script to be called, so that it logs the visitor into a file. To do this, you would place an SSI tag into your web page. The tag in this case, would look something like:

<!--#exec cgi="/cgi-bin/count.cgi" -->

This small tag, which is hidden in the html coding of your page is telling the server to: 1. Go to the cgi-bin 2. Execute count.cgi That's it! The information has been captured and processed by the count.cgi script. Of course, that's the short version of what happens. The long version would no doubt, would take us far beyond the scope of this document. PLEASE do not use the .shtml extension on "all" of your web pages unless it's absolutely necessary. With a busy web site, this means that every page must be executed, as opposed to just read. This as you can appreciate, can add considerable memory and CPU load to the system. As always, read the instructions that came with your script carefully. They should provide specific instructions on how to configure the script, as well as the SSI tag.

A: 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.

A: First you must create a page with a .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.

A: The valid SSI directives are as follows: echo Syntax: echo var="environment-variable" Echo inserts the value of one or more SSI environment variables. include 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"--> fsize 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. flastmod 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"-->. config 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"

printenv Syntax: printenv This directive prints a complete list of all existing SSI variables and their values. It has no attributes. For example: <!--#printenv--> set Syntax: set var="variable" value="value" This directive sets the value of an environment variable. For example: <!--#set var="country" value="United States"-->

A: 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"-->
<!--#else-->
<!--#endif--> 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

A: DOCUMENT_NAME The filename of the current HTML document. For example: This file is called . DOCUMENT_URL The URL of the current file. For example: This document is located at . QUERY_STRING_UNESCAPED An UUencoded query string whose metacharacters are escaped with a backslash (\). DATE_LOCAL The local date and time. For example: Here in San Diego, it is now . DATE_GMT The current Greenwich Mean Time. For example: The current time is GMT. LAST_MODIFIED The date and time when the current file was last modified. For example: I last modified this page on .

A: SERVER_SOFTWARE=Stronghold/2.0 The name and version number of the server software SERVER_NAME=host 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 HTTP_HOST=host 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 REMOTE_HOST=host The hostname or IP number of the client host or proxy server that originated the request REMOTE_PORT=port The client-side port number that originated the request REMOTE_ADDR=IP The IP number of the client host REMOTE_USER=username The remote username, if the script is subject to basic authentication REMOTE_IDENT=ident The remote username as supplied by identd, if available SERVER_PROTOCOL=protocol/version 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 REQUEST_METHOD=method The method used in this request, such as GET or POST AUTH_TYPE=method The authentication method used in this request, if any CONTENT_TYPE=MIME-type The MIME type of any data attached to the request header CONTENT_LENGTH=n The size, in bytes, of any data attached to the request header SCRIPT_NAME=path/to/script The URL of the requested script SCRIPT_FILENAME=absolute/path/to/script The absolute path to the requested script SCRIPT_URI=method://host/path/to/script The URL of the requested script SCRIPT_URL=path/to/script The URL of the requested script QUERY_STRING=string The query-string for this transaction, embedded in the requested URL

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