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Programming Perl scripts for Linux and Win32

If your new to Perl, then you should start as you mean to go on. If you are already a Perl programmer, then this guide should (unless you're really good) help you improve your skills and scripts.

Perl can run on both Linux (Unix) systems and Windows (Win32). Perl can also run as ASP (PerlScript) on Win32 IIS. Most programming guides for Perl will teach you how to write scripts for Linux. You then later have to update your code to work for Win32 from another guide. It's all a lot easier if you code your script for Linux and Win32 in the first place. This guide will give you the template for coding universal scripts that can run as .pl, .cgi or .asp or if you're running Apache, '.anything'. It will also show you how to make your database enabled programs work with MySQL, MS SQL (ODBC) or ADO. In my opinon this is the future of how all perl web applications should be written. By Perl web applications I mean those such as on my site CosmicScripts.com, if you want your scripts to be usable by as many people as possible, on as many servers as possible then follow this guide!

Getting started

Here is the code you should use to start all your scripts. What does this code do? It flushes the buffers, checks which operating system your on, gets the system path to it's installed folder and adds this path to perl @INC modules folder list and sets this as the working directory, gets the name and extention of the itself, checks if it is running in ASP, loads CGI::Carp for friendly error handling, loads our free restricted Cosmic module, loads the sendmail module if on Win32, loads the ASP module if in ASP mode and populates Perl's standard ENV variable with the ASP environment variables. The part of this code below the commented #Script Start# will be described later. This leaves you with some useful variables to work with:-

$aspmode

This is set to 1 if the program is running as ASP, otherwise it's undefined.

$operatingsystem

This is set to 1 for Unix and 0 for Win32.

$systempath

This is set to the full system path to the scripts working folder.

$scriptname

This is the name of the script without the extention.

$extention

This is set to the working scripts extention, be that .pl, .cgi or .asp.

$osstring

This is set to a readable friendly description of the operating system.

$slash

This is kept for backward compatability, and set to the operating systems path separator. Perl for win32 now uses / instead of the double \\.

For this code to work you will need the modules ASP.pm from Matt's Perl Pages thanks for Matt for a very useful script. You also need SendMail.pm from Simon Tneoh Chee-Boon and our own slimmed down Cosmic.pm module. Why have I chosen these modules instead of others from CPAN? I'm always impressed when a module doesn't have to be installed into perl with make or ppm. If you are making commercial or highly distributed scripts you can't expect everyone to install some obscure perl module. Even if they want to most people are on shared hosting accounts, with very incooperable hosting companies. These modules just need to go in the same folder as your script and you can use them at will.

The code below the commented #Script Start# is also useful. Firstly it prints the Text/HTML content type header if it's not in ASP mode. It then populates the variables %FORM and %QUERY with hashed values from query string and posted form data. Lastly it checks for ASP mode and populates %FORM in the way needed when running in ASP mode.

Now you have a good starting framework for writing a versatile script. The only problem is that running in ASP mode you need to have:-
<%@ Language=PerlScript %>
<%
..... All script code here
%>
Around your scripts. So if people want to run your scripts as .asp they'll need to add this code. But there is a solution, I'll be bringing you an application you can use to include in with your scripts that will ask the end user which mode they want to run the scripts, .pl, .cgi or .asp, and adjust the script files appropriately for them :) I'm currently deciding on which program would be best to make this utility in. At the moment NSIS from NullSoft is in the lead, I think it will provide everything I need. As soon as I get a bit of time I'll get started on this project. I'm looking forward to it :)

The Cosmic.pm module

If you've installed any of my scripts you'll see that they all come with a module called cosmic.pm. This is my module I have built up over the years for doing all kinds of stuff. Unfortunately I'm not (as yet) going to make it avilable for everyone to use. But I am however going to put together a slimmed down version with some routines I'm sure you'll find useful. Of course this module doesn't need to be properly installed or compiled into perl, you can just throw it in with your scripts.

DataBase programming

I'm not going to write you a full guide on SQL or doing database work. There are plenty. I am however going to show you how to setup a database connection for MySQL, MS SQL (ODBC) and ADO (ASP only). What about the syntax differences between MySQL, SQL and MS SQL SQL? (lots of SQL there, lol) Code your SQL syntax for MySQL, then use the module I'm developing MytoMSSQL.pm which will translate your SQL to MS SQL. Here is the current state of this module. If you want to make use of it feel free to contribute and email me with new rountines that you add. Once this module is built up it'll be heading for CPAN.