Server Side Includes

What is a Server-Side Include? It's simply a modified HTML file of sorts. Let's say you have a "standardized" header and footer for all of your web pages, like we do here at SmartNet. If you didn't use a SSI, you'd have to manually key in everything for each and every webpage. If you did use an SSI, however, you could enter a SINGLE tag and have everything there! No more retyping hundreds of documents just because someone changed their e-mail address!!

Note that SSI's are not for the inexperienced HTML authors!! If you're just learning HTML, hold off on SSI's until you get a decent grasp of regular HTML. There is just too much that can go wrong!

Using SSI's

All SSI's are accessed in this manner: 
SSI documents must have the extension of .shtml. Not .sht, .SHTML, .ShTmL, or whatever else, but .shtml.

NOTE The space before -->! It is very important!! Each command takes different arguments, most only accept one tag at a time. Here is a breakdown of the commands and their associated tags:

config
The config directive controls various aspects of the file parsing. There are three valid tags:
- errmsg controls what message is sent back to the client if an error includes while parsing the document. When an error occurs, it is logged in the server's error log.
  Example: 
- timefmt gives the server a new format to use when providing dates. This is a string compatible with the strftime library call under most versions of UNIX.
  Example: 
- sizefmt determines the formatting to be used when displaying the size of a file. Valid choices are bytes, for a formatted byte count (formatted as 1,234,567), or abbrev for an abbreviated version displaying the number of kilobytes or megabytes the file occupies.
  Example: 
include
include will insert the text of a document into the parsed document. Any included file is subject to the usual access control. This command accepts two tags:
- virtual gives a virtual path to a document on the server, starting at the server's root. You must access a normal file this way, you cannot access a CGI script in this fashion. You can, however, access another parsed document.
  Example: 
- file gives a pathname relative to the current directory. ../ cannot be used in this pathname, nor can absolute paths be used. As above, you can send other parsed documents, but you cannot send CGI scripts.
  Example: 
echo prints the value of one of the include variables (defined below). Any dates are printed subject to the currently configured timefmt. The only valid tag to this command is var, whose value is the name of the variable you wish to echo.
Example: 
fsize prints the size of the specified file. Valid tags are the same as with the include command. The resulting format of this command is subject to the sizefmt parameter to the config command.
Example: 
The file /header.html is 1k bytes.
flastmod prints the last modification date of the specified file, subject to the formatting preference given by the timefmt parameter to config. Valid tags are the same as with the include command.
Example: 
The file /header.html was last modified on Wednesday, 26-Jun-2002 16:40:04 EDT

SSI Environment Variables

A number of variables are made available to parsed documents. In addition to the CGI variable set, the following variables are made available:

DOCUMENT_NAME: The current filename.
DOCUMENT_URI: The virtual path to this document (such as /docs/tutorials/foo.shtml).
QUERY_STRING_UNESCAPED: The unescaped version of any search query the client sent, with all shell-special characters escaped with \.
DATE_LOCAL: The current date, local time zone. Subject to the timefmt parameter to the config command.
DATE_GMT: Same as DATE_LOCAL but in Greenwich mean time.
LAST_MODIFIED: The last modification date of the current document. Subject to timefmt like the others.

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