CGI enables you to do that and much more. From mail-forms and counter programs, to the most complex database programs that generate entire websites on-the-fly, CGI programs deliver a broad spectrum of content on the web today. Some web space providers will give you access to a limited number of CGI scripts that they have already installed on the server, but they may not let you use other CGI programs on their server. Also, most free web space provides do not provide CGI access, but contact them to be sure. They may provide CGI.
or, Writing CGI scripts to process Web forms
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So it's 4:00, your boss needs a CGI script written by 4:30, andyou don't even know what CGI stands for. You've come to the rightplace.
3D, also referred to as CGI (computer generated imagery), is the most popular type of animation for feature films currently, and it's become common in TV and short films as well. This is also the same type of animation used to create digital characters for live-action films and animation for video games.
There's not much to it, despite any intimidating hype you mighthave heard. If you can read from STDIN and write to STDOUT,then you can write CGI scripts.If you're a programmer already, this primer can teach you the basics of CGI in a few minutes. If you're not a programmer, this primer won't help you much-- sorry. Learn some programming, even shell scripting, and come back when you're done. Good luck! How to get google drive on your desktop.
This primer focuses on writing CGI scripts to process HTML forms on the Web.It skips some details, but can bring you up to speed fast (literally an hour or less), and covers 90% of real-world situations.When you feel the need, check out thefull CGI spec.For help with writing HTML forms, seethis tutorial fragment,or this documentation at NCSA.
Once you've read this page, see thefootnotes for sample scripts andother topics.
What is CGI?
Free Cgi Maker
CGI is not a language. It's a simple protocol that can be used to communicate between Web forms and your program. A CGI script can be written in any language that can read STDIN, write to STDOUT, and read environment variables, i.e. virtually any programming language, including C, Perl, or even shell scripting.Structure of a CGI Script
Here's the typical sequence of steps for a CGI script:
- Read the user's form input.
- Do what you want with the data.
- Write the HTML response to STDOUT.
The first and last steps are described below. How do you stream direct tv.
Reading the User's Form Input
When the user submits the form, your script receives the form data asa set of name-value pairs. The names are what you defined in the INPUT tags (or SELECT or TEXTAREA tags), and the values are whatever theuser typed in or selected. (Users can also submit files with forms, butthis primer doesn't cover that.)
This set of name-value pairs is given to you as one long string, whichyou need to parse. It's not very complicated, and there are plentyof existing routines to do it for you.Here's one in Perl,a simpler one in Perl, orone in C.For a more elaborate CGI framework, see Perl'sCGI.pmmodule.The CGIdirectory at Yahoo includes many CGI routines (and pre-written scripts), in various languages.
If that's good enough for you, skip to the next section. If you'd rather do it yourself, or you're just curious, the long string is in oneof these two formats:
'name1=value1&name2=value2&name3=value3'
'name1=value1;name2=value2;name3=value3'
So just split on the ampersands or semicolons, then on the equal signs. Then, do two more things to each name and value:
- Convert all '+' characters to spaces, and
- Convert all '%xx' sequences to the single character whose ascii value is 'xx', in hex. For example, convert '%3d' to '='.
So where do you get the long string? That depends on the HTTP method theform was submitted with:
- For GET submissions, it's in the environment variable QUERY_STRING.
- For POST submissions, read it from STDIN. The exact number of bytes to read is in the environment variable CONTENT_LENGTH.
(If you're wondering about the difference between GET and POST, see thefootnote discussing it.Short answer: POST is more general-purpose, but GET is fine for small forms.)
Sending the Response Back to the User
First, write the line
Content-type: text/htmlplus another blankline, to STDOUT. After that, write your HTML response page to STDOUT,and it will be sent to the user when your script is done. That's allthere is to it.
Yes, you're generating HTML code on the fly. It's not hard; it'sactually pretty straightforward. HTML was designed to be simple enoughto generate this way.
If you want to send back an image or other non-HTML response,here's how to do it.
That's it. Good Luck!
See how easy it is? If you still don't believe me, go ahead and writea script. Make sure to put the file in the right place on your server,and make it executable; see thisfootnote for more hints.
Free Cgi Program For Windows
Before you write too many scripts, learn aboutCGI security issues.
When you need to know more about CGI, see the complete CGI specification at NCSA.W3C also maintains a CGI page with links toany documents you might need.
Cgi For Free
Oh yeah, CGI stands for Common Gateway Interface-- in otherwords, a standard ('common') way of communicating ('interface') between different processes ('gateway', sort of).
Other Things to Play With
Free Cgi Editor
See the Footnotes Page for the following stuff:
© 1996-1998, 2002 James Marshall(comments welcome; for questions, please scan the FAQ first)
| Last Modified: April 12, 2002 | http://www.jmarshall.com/easy/cgi/ |
