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Author image Michael Accardo


HTML::Perlinfo - Display a lot of Perl information in HTML format


        use HTML::Perlinfo;



This module outputs a large amount of information about your Perl installation in HTML. So far, this includes information about Perl compilation options, the Perl version, server information and environment, HTTP headers, OS version information, Perl modules, and more.

HTML::Perlinfo is aimed at Web developers, but almost anyone using Perl may find it useful. It is a valuable debugging tool as it contains all EGPCS (Environment, GET, POST, Cookie, Server) data. It will also work under taint mode.

The output may be customized by passing one of the following options.


There are 8 options to pass to the perlinfo funtion. All of these options are also object methods. The key difference is their case: Captilize the option name when passing it to the function and use only lower-case letters when using the object-oriented approach.


The Perl version, build date, and more.


Shows all predefined variables from EGPCS (Environment, GET, POST, Cookie, Server).


All configuration values from config_sh. INFO_ALL shows only some values.


Apache HTTP server information, including mod_perl information.


All installed modules, their version number and description. INFO_ALL shows only core modules. Please also see HTML::Perlinfo::Modules.


Post-execution dump of loaded modules (plus INFO_VARIABLES). INFO_ALL shows only core modules. Please also see HTML::Perlinfo::Loaded.


Perl license information.


Shows all of the above defaults. This is the default value.


There are two styles of programming with Perlinfo.pm, a function-oriented style and an object-oriented style.

Function-oriented style:

        # Show all information, defaults to INFO_ALL

        # Show only module information. This shows all installed modules.

Object-oriented style:

        $p = new HTML::Perlinfo;

        # You can also set the CSS values in the constructor!
        $p = HTML::Perlinfo->new(
                bg_image  => 'http://i104.photobucket.com/albums/m176/perlinfo/camel.gif',
                bg_repeat => 'yes-repeat'

More examples ...

        # This is wrong (no capitals)

        # But this is correct
        # Ditto


You can capture the HTML output and manipulate it or you can alter CSS elements with object attributes.

For further details and examples, please see the HTML documentation in the HTML::Perlinfo distribution.


Displaying detailed server information on the internet is not a good idea and HTML::Perlinfo reveals a lot of information about the local environment. While restricting what system users can publish online is wise, you can also hinder them from using the module by installing it outside of the usual module directories (see perldoc -q lib). Of course, preventing users from installing the module in their own home directories is another matter entirely.


1. Print the content-type header first if you are using the module in a CGI setting. (mod_perl handles this for you automatically.) If you do not print the header, you will produce an internal server error. Of course, you can forgo a Web server entirely and use the module at the command-line. Please see the perlinfo tool included in this distribution.

2. If the HTML takes too long to load in the browser, then you can try flushing the output buffer. By flushing the buffer, the HTML will start appearing immediately.

INFO_APACHE relies soley on environment variables. If you don't use Apache, there is nothing to worry about. You do not need to turn INFO_APACHE off or anything. The section will simply not appear. Any Web server information will still be in the environment variables, unless you configure your server to not report information.

INFO_VARIABLES did not work correctly until version 1.52.

INFO_LOADED is the only option whose output cannot be assigned to a scalar.

Since the module outputs HTML, you may want to use it in a CGI script, but you do not have to. Of course, some information, like HTTP headers, would not be available if you use the module at the command-line. If you decide to use this module in a CGI script, make sure you print out the content-type header beforehand. For example:

        use HTML::Perlinfo;

        print "Content-type: text/html\n\n";

Some might notice that HTML::Perlinfo shares the look and feel of the PHP function phpinfo. It was originally inspired by that function and was first released in 2004 as PHP::Perlinfo, which is no longer available on CPAN.


If you'd like to report an issue you can use github's issue tracker.


Config. You can also use "perl -V" to see a configuration summary at the command-line.

CGI::Carp::Fatals, Apache::Status, App::Info, Probe::Perl, Module::CoreList, Module::Info, among others.

Also included in the Perlinfo distribution: perlinfo, HTML::Perlinfo::Loaded, HTML::Perlinfo::Modules


Mike Accardo <accardo@cpan.org>


   Copyright (c) 2019, Mike Accardo. All Rights Reserved.
 This module is free software. It may be used, redistributed
and/or modified under the terms of the Perl Artistic License.