CHAPTER EIGHTEEN -
PHP is a server-side HTML embedded scripting
language that was developed in C and is designed especially for working with relational
A PHP program is embedded directly in the HTML document. It must have a .phtml extension
in order for the server to look for PHP code in the document. Here is
how you embed the PHP:
insert PHP code here
PHP is an excellent way to embed scripting
languages such as C, Java, and Perl into your website's pages. It is a very
efficient way to implement advanced tasks such as database queries, as well.
You can implement and maintain a mySQL
database entirely with the use of PHP as well. You might want to see this Introduction to PHP if you aren't sure what PHP is.
These are some additional sites and resources which
will help you learn and develop your PHP skills, as well as answer any questions that you
Learning PHP Resources Official PHP Website Docs
Official Zend Website
DevShed PHP Section
The PHP Resource Index
Programs and Directories HotScripts PHP
PHP Code Exchange
(useful mySQL DB manager)
Links to More PHP Resources
Linux Guruz PHP Resources
PHP.com Links Section
ABOUT SERVER SIDE INCLUDES
A server side include, or SSI, is a piece of code that is embedded into
an HTML page and interpreted by the the server before the page is sent to the client's
browser. SSI's allow you to include information in your HTML files like a file's date of
last modification, another HTML file, a counter, or the output of any CGI script.
Server Side Includes are server intensive. Because all
files need to be parsed by the server, having all of your pages SSI would cut performance.
Any file that has the extension .shtml will
automatically be parsed by the server. You can use index.shtml instead of index.html
as your default directory file.
SSI Commands The following is a list of Server Side
Include basics: A server side include command is contained within a comment tag: <!--#command argument="value"
Syntax must be correct, or your include will not work.
To include the contents of another file in a shtml file,
you use the include command.
The include command has two possible arguments: virtual
"Virtual" is used when the path to the document
is given relative to the document root (usually your www directory.)
"File" is used when the path to the document is
given relative to the shtml file itself. However, you cannot use "file" to go up
a directory ( "../slime.html" won't work.)
Say we want to include the file named
"file.html" which resides in the same sub directory of as this shtml file.
- To include it using "virtual," you would use:
- <!--#include virtual="/mirror/ssi/file.html"
This would return: This is from file.html
- To include it using "file," you would use:
- <!--#include file="file.html" -->
This would return: This is from file.html
The echo command includes, or "echoes," the
contents of an environment variable. Here are some examples showing the SSI tag and the
- <!--#echo var="DOCUMENT_NAME" -->
- This document is named: man7.htm
- <!--#echo var="DATE_LOCAL" -->
- You accessed this document: Tuesday, 03-Jan-98 14:02:35 EDT
- <!--#echo var="DATE_GMT" -->
- This is the same as the above, but in Greenwich Mean Time:
Tuesday, 03-Jan-98 18:02:35 EST
- <!--#echo var="DOCUMENT_URI" -->
- The URI (the path form document root) of this document is:
- <!--#echo var="LAST_MODIFIED" -->
- This document was last modified: Friday, 01-Nov-96 15:22:57
- <!--#echo var="HTTP_REFERER" -->
- The user came by way of a link from:
- <!--#echo var="HTTP_USER_AGENT" -->
- The browser used to access this document was: Mozilla/4.0b3
[en] (WinNT; I)
Echo Command Values
SERVER_SOFTWARE server application
SERVER_NAME hostname of the server
SERVER_PROTOCOL server protocol
SERVER_PORT listening TCP port
REQUEST_METHOD HTTP method used by the client
REMOTE_HOST domain name of the client, note DNS option must
REMOTE_ADDR IP address of the client
AUTH_TYPE method that the client used for authorization
REMOTE_USER username entered by the remote client
CONTENT_TYPE MIME type of the content posted by the client
CONTENT_LENGTH size of the data posted by the client
DOCUMENT_NAME name of the document requested
DOCUMENT_URI URL of the document requested
DATE_LOCAL current date, format specified by the config
DATE_GMT The current GMT, format specified by the config
LAST_MODIFIED document modified date, format specified by the
PAGE_COUNT number of hits on the current document
since server came on-line
TOTAL_HITS number of documents server has served since
REFERRER The URL of the document the viewer came from
The exec command executes a Unix command or CGI script. It
always takes the argument "cmd".
- <!--#exec cmd="/usr/bin/date" -->
This executes the Unix date command.
- <!--#exec cgi="./hello.cgi" --> This
executes the CGI script, hello.cgi.
If you look carefully you will notice the second line uses
the statement exec cgi opposed to the previous line which used exec cmd. The
second line is calling a CGI script that was written, the first a UNIX command. Here is
the perl code contained in hello.cgi:
All the environment variables passed to the CGI script are
the same as those for the shtml file itself.
So, you cannot pass a query string using a question mark
(?), as in:
The query string passed to the CGI script will be the same
as the query string passed to the shtml file itself. If this file were referenced as
"ssi.shtml?snort", than the word "snort" would also be passed to the
"hello.cgi" script above.
The fsize command returns the size of the specified file
in bytes. It uses the argument "virtual," which is the path to the file is given
relative to the document root (usually your www directory.)
To find the size of picture.gif, you would use:
This would return then return the file size.
Your probably now asking, what can I use this for?
Example: You offer some files available for download on your site and would like to give
people an idea of how big the files are.
The flastmod command returns the date the specified file
was last modified.
The flastmod command uses the argument
"virtual," which is the path to the file is given relative to the document root
(usually your www directory.)
To find the last modified date of a file, you would use:
This would return: Friday, 06-Sep-96 03:36:06 EDT
The config command is used to control how the results of
other SSI are displayed. There are three possible arguments: timefmt, sizefmt and errmesg.
To set the format for the date to dd/mm/yy, you will use:
The date will now be displayed as: 03/06/97
The field descriptors used by this SSI tag are the same as
those used by the Unix date command.
Notice the dates displayed above this config command use
the normal date format, the one below it uses the new format.
To set the format for how file sizes are displayed, you
<!--#config sizefmt="abbrev" -->
<!--#config sizefmt="bytes" -->
Depending on whether you want the size given in total
bytes or abbreviated as "1k".
To set error message returned when an SSI tag fails, use:
<!--#config errmsg="Error" -->
A failed SSI tag will now return: Error
Reasons for Using SSI:
SSI is often used to include something into an HTML page. You can insert the contents of
one HTML page into another page. An example of a practical usage for this would be to
include your e-mail address at the bottom of each page. If you do this as an include, then
when your e-mail address changes, you will only have to update it on one page and not your
entire web site. Another usage is to call cgi scripts into action. Many counters, clocks,
and other scripts are called using SSI. The command used will most likely be provided in
the documentation of your cgi script.
More Help for using SSI can be found at:
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