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Examples: No need to create a CGI object when using the function-based interface.
Examples: HTML5 makes things simpler
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print << "EndOfHTML";
print << "EndOfHTML";
<!DOCTYPE html
<!DOCTYPE html>
<html>
PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"
>
<html xmlns="http://www.w3.org/1999/xhtml" lang="en-US" xml:lang="en-US">
<head>
<head>
<title>A Simple CGI Page</title>
<title>A Simple CGI Page</title>

Revision as of 14:24, 18 December 2015

CGI.pm
Original author(s)Lincoln Stein
Developer(s)Lee Johnson
Stable release
4.21 / 2015-06-22
PlatformPerl
TypePerl module for CGI
Websitemetacpan.org/release/CGI

CGI.pm is a large and widely used Perl module for programming Common Gateway Interface (CGI) web applications, providing a consistent API for receiving and processing user input. There are also functions for producing HTML or XHTML output, but these are now unmaintained and are to be avoided.[1] CGI.pm was a core perl module but has been removed as of v5.22 of perl.[2] The module was written by Lincoln Stein and is now maintained by Lee Johnson.

Examples

Here is a simple CGI page, written in Perl using CGI.pm (in object-oriented style):

#!/usr/bin/env perl

use strict;
use warnings;

use CGI;

my $cgi = CGI->new;

print $cgi->header('text/html');

print << "EndOfHTML";
<!DOCTYPE html>
<html>
    <head>
        <title>A Simple CGI Page</title>
        <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
    </head>
    <body>
        <h1>A Simple CGI Page</h1>
        <form method="post" enctype="multipart/form-data">
            Name: <input type="text" name="name"  /><br />
            Age: <input type="text" name="age"  /><p />
            <input type="submit" name="Submit!" value="Submit!" />
        </form>
        <hr />
EndOfHTML

if ( my $name = $cgi->param('name') ) {
    print "Your name is $name.<br />";
}

if ( my $age = $cgi->param('age') ) {
    print "You are $age years old.";
}

print '</body></html>';

This would print a very simple webform, asking for your name and age, and after having been submitted, redisplaying the form with the name and age displayed below it. This sample makes use of CGI.pm's object-oriented abilities; it can also be done by calling functions directly, without the $cgi->, however the necessary functions must be imported into the namespace of the script that requires access to those functions:

#!perl

use strict;
use warnings;
use CGI qw/ :standard /;

print header('text/html');

# ... HTML output same as above example

if ( my $name = param('name') ) {
    print "Your name is $name.<br />";
}

if ( my $age = param('age') ) {
    print "You are $age years old.";
}

print '</body></html>';

Note: in many examples $q, short for query, is used to store a CGI object. As the above example illustrates, this might be very misleading.

See also

References