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CGI-PERL Tutorials

Random subroutines in Perl
I'll bet your first question might be "why on earth would I ever want to call subroutines randomly?". Admittedly, it isn't a need that comes up that often, but (for example) it's used right here on this very page that you are reading.
Friday, 23rd November 2007

Log Script Use
How many old, unused (or under-used) CGI scripts do you have lingering on your server, taking up space? You may not be as guilty of abandoning CGI software in lieu of newer versions as we are (we've been creating, and testing software on the same server for 8 years) but odds are you've got a few dusty, unused scripts lurking about.
Monday, 25th July 2005

Creating Perl Modules for Web Sites
When you are writing your own code, you are more apt to use someone else's module than write your own, unless your project gets fairly large and complex. Small scripting tasks just don't need the advantages modules offer.
Tuesday, 19th July 2005

Bit Vector, Using Perl Vec
A bit vector is just an array of bits; subsets of bits within the bytes have some meaning. That allows more compact storage for certain types of data. For example, if you only needed boolean on-off values, you can store eight values in one byte.
Tuesday, 19th July 2005

Build a Perl/CGI Voting System
Many Web-deployed applications are written within elaborate database-driven server-side development frameworks such as PHP and Java™ servlets, but for simple applications (for example, where the entire dataset fits comfortably within a Web server's RAM), data persistence can be easily accomplished using locked DBM files in conjunction with the Perl MLDBM module. This article presents a real-world example -- a Web-based voting application -- that highlights the use of minimal external modules, forgoes using client-based cookies, and takes advantage of CGI attributes.
Tuesday, 5th July 2005

Perl Range Operator
In a list context, this operator is easy to use and understand. It is much more confusing in a scalar context, and is often badly explained in books and webpages.
Thursday, 16th June 2005

Creating Perl Modules for Websites
When you are writing your own code, you are more apt to use someone else's module than write your own, unless your project gets fairly large and complex. Small scripting tasks just don't need the advantages modules offer. However, there is a case where modules might make perfect sense: web server cgi scripts often repeat the same tasks.
Thursday, 16th June 2005

Perl binding, or vs. ||
Perl has "||" and "or". While "or" can't be used in bit operations, either one can be used in logical flow control - but there is an important difference between them.
Thursday, 16th June 2005

Transferring Mail to a New Mail Server
Sometimes we just have to move on. Your current mail server may just not be meeting your needs, so you've put up something new. But what about old mail? If your servers are identical (Sendmail to Sendmail, etc.) or use the same mailbox storage format, you may be able to just transfer files directly. If not, read on..
Tuesday, 3rd May 2005

Goal Seeking Code
This is an extremely unsophisticated program that demonstrates evolutionary DNA. You start by passing it a string:
Tuesday, 3rd May 2005

Replacing a Spreadsheet
Spreadsheets can be powerful tools, and particularly so in the hands of an expert user. A spreadsheet can be used to reorganize data and to extract information not otherwise available. For example, at a client site, an application report generates a listing of hourly billing, but can't give the cross-reference totals desired. The raw output looks something like this:
Tuesday, 3rd May 2005

Text::Autoformat: Smart Text Reformatting with Perl
I've been using http://groups-beta.google.com/ for Newsgroup posting for a while now. It's convenient for me because of my nomadic life style where I have different ISP's and often different machines with varying OSes. Google only needs a browser, and they aren't overly fussy about that, either.
Tuesday, 3rd May 2005

Handling Missing Data in Inputs
Missing data can be very annoying to a programmer. In fact, it is so annoying that very often we'll write separate programs to clean up data and eliminate unpleasant conditions so that the main program doesn't have to deal with it. Here, I'll show some examples of the kind of problems we see.
Tuesday, 3rd May 2005

Building Perl projects with MakeMaker
If you've used UNIX or Linux for some period of time, you've probably written a few Perl programs to automate simple tasks. Each of these programs does something basic and simple that might otherwise take you 10 or 20 minutes to do by hand. In this article, Sean will show you how to convert just such a Perl program into a far more robust programming project, one that will be generic enough to be widely distributed across many disparate platforms.
Sunday, 1st May 2005

Web Log Analysis
There are many tools available to analyze web page statistics. One of the most popular is Analog, but any web search will turn up hundreds or perhaps even thousands more. There are also options like Hitbox which provides statistics gained through code included in your web pages.
Saturday, 30th April 2005

Tips for Convenient CGI Scripting
Any CGI programmer benefits from knowing and using ready-made libraries. In this article Eugene Logvinov shows how CGI modules taken from CPAN can not only help you to work effectively and conveniently, but can also provide you with an excellent code and reference library. Consequently, embedding POD (Plain Old Documentation) in the module turns out to be a good choice.
Thursday, 28th April 2005

Perl Net::FTP
Before the wide spread availability of Perl, I would script ftp transfers with .netrc, ksh scripts and other clumsy ways. None of those methods are fun, flexible or easy. On the other hand, Perl's Net::FTP module is all of that.
Wednesday, 27th April 2005

Fork and Exec with Perl
Recently I had a project that required a number of different programs that will mostly run all the time, but need to be restarted now and then with different parameters. Normally, the first thing I think of for a program that runs constantly is inittab or svc (daemontools). The svc facility is the more flexible of the two, and will be what I'll use in the final design, but in the "thinking" stages I played with using a Perl program launcher and controller. What we have is a config file that specifies programs
Wednesday, 27th April 2005

Automate Perl Module Deployment
If you run Perl across many different computers of any sort, you know how frustrating it can be to install Perl extension modules across those machines. The administrative process is even worse if you have a Web server farm and need to keep each machine up to date with a set suite of extension modules for your installation.
Wednesday, 27th April 2005

Cultured Perl: Embedding Perl in database tables
In this installment, Ted looks at Perl and databases. Specifically, he works with the Class::DBI CPAN module and MySQL to introduce you to embedding Perl in database tables. Databases and the applications that use them are essential to today's computing infrastructures. They are everywhere, from plain-text databases such as the UNIX® /etc/passwd file to large databases such as those that track shopping habits or fight credit card fraud.
Wednesday, 27th April 2005

Perl Input
Perl has wonderful I/O capabilities. I'm only going to cover input here: reading from files or standard input. There are two ways to do that (actually a lot more than two, but this is supposed to be introductory material): you can open a specific file, or you can pass files on the command line and either open them individually or just ignore the whole thing and pretend everything is coming from STDIN.
Monday, 25th April 2005

Perl Sorting
Arrays often need sorting. Perl has built-in ways to help you, but as usual, there's more than one way to do it. To play with the examples shown here, you'll need a file containing a few lines of words.
Monday, 25th April 2005

Perl Getopt and GetOptions
Two Perl modules (Getopt and Getoptions::Long) work to extract program flags and arguments much like Getopt and Getopts do for shell programming. The Perl modules, especially GetOptions::Long, are much more powerful and flexible.
Friday, 22nd April 2005

Running a CGI Script When Page Loads
From statistics gathering to silent webmaster notification to email subscription solicitation, there can be any of many reasons for triggering a CGI script to run when a web page loads.
Thursday, 21st April 2005

Tips for Convenient CGI Scripting
Any CGI programmer benefits from knowing and using ready-made libraries. In this article Eugene Logvinov shows how CGI modules taken from CPAN can not only help you to work effectively and conveniently, but can also provide you with an excellent code and reference library. Consequently, embedding POD (Plain Old Documentation) in the module turns out to be a good choice.
Thursday, 14th April 2005

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