Used when the client is sending attached content to the server. These variables play an important role while writing any CGI program.
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The browser uses this value to report the estimated download time for a file.Īll the CGI program will have access to the following environment variables. The length, in bytes, of the data being returned. The date of last modification of the resource. You can use this filed to redirect a request to any file.
The URL that should be returned instead of the URL requested. A valid date string should be in the format 12:00:00 GMT. This should be used by the browser to decide when a page needs to be refreshed. The date the information becomes invalid. S.No.Ī MIME string defining the format of the file being returned. There are few other important HTTP headers which you will use frequently in your CGI Programming. All the HTTP header will be in the following form The line Content-type:text/html\r\n\r\n is part of HTTP header which is sent to the browser to understand the content. Print 'Hello Word! This is my first CGI program' By convention PERL CGI files will have extention as. This directory is called CGI Directory and by convention it is named as /cgi-bin. All the CGI Programs be executed by the HTTP server are kept in a pre-configured directory. CGI Architecture Diagram Web Server Support & Configurationīefore you proceed with CGI Programming, make sure that your Web Server supports CGI and it is configured to handle CGI Programs. These CGI programs can be a PERL Script, Shell Script, C or C++ program etc.
This function is called the Common Gateway Interface or CGI and the programs are called CGI scripts. However, it is possible to set up the HTTP server so that whenever a file in a certain directory is requested that file is not sent back instead it is executed as a program, and whatever that program outputs is sent back for your browser to display. Web browser takes response from web server and displays either the received file or error message. Web Server will parse the URL and will look for the filename in if it finds that file then sends back to the browser otherwise sends an error message indicating that you have requested a wrong file. Your browser contacts the HTTP web server and demand for the URL ie. To understand the concept of CGI, lets see what happens when we click a hyper link to browse a particular web page or URL. The current version is CGI/1.1 and CGI/1.2 is under progress. The Common Gateway Interface, or CGI, is a standard for external gateway programs to interface with information servers such as HTTP servers. The CGI specs are currently maintained by the NCSA and NCSA defines CGI is as follows − The Common Gateway Interface, or CGI, is a set of standards that define how information is exchanged between the web server and a custom script.