Notes from the Perl FAQ
Like the fellow that never read his car’s owner’s manual, I had never read the entire Perl FAQ. I finally did it over the holidays, and these are some notes that I took.
Last Updated: Fri, 20 Jan 2012
Keith A. Carangelo
About
I am a
software engineer
with twenty years experience developing
real-time applications for a number of different industries.
I have worked on medical and military embedded systems
and distributed applications in storage, networking, and monitoring.
I am also a freelance web designer with national clients. I specialize in solving issues with existing sites; giving a professional engineering edge to sites designed by graphic designers or artists.
Email
mail@kcaran.com
Fantasy Sports
home :: technology
Ubuntu Version (tested on 9.10 Karmic Koala)
No such file or directoryectory
When I execute a CVS update command at work, I often get the following error:
[caran@mater safetypublic]$ cvs -q update -AdP : No such file or directoryectory /home/cvs/safetypublic/rsvp cvs update: skipping directory rsvp
No such directoryectory? What the heck is that??
Last Updated: Thu, 10 Nov 2011
Del.icio.us Complete Firefox Plugin for Firefox 4.x, 5.0
I love del.icio.us (or the Yahoo’ed, dummied-down delicious.com) to manage my bookmarks. Unfortunately, the Firefox extension I’m used to using, del.icio.us Complete, is no longer supported, and thus doesn’t work with the latest versions of Firefox.
This is my hacked version of the Delicious Complete extension, which allows it to run in version 4.0 or later. Please note: consider the extension beta software. It works fine for me on Ubuntu and Windows XP, but I haven’t done extensive testing. Please let me know if you have any issues.
Download and Install Del.icio.us Complete
Thanks to verymurklins for providing the original hack for version 3.0
Last Updated: Tue, 06 Sep 2011
Calling a Perl CGI script from within another CGI script
Awhile back we had an issue where a coworker wanted to use one of my Perl CGI scripts inside of her scripts, using the backticks method to have it spit its output to the webpage. But for some reason, my script refuse to recognize the arguments she was passing it. The weird thing was, if we ran her script from the command line, everything worked fine.
The issue is in the way CGI.pm detects whether it is being called from a web browser or from the command line. It checks for the presence of the REQUEST_METHOD environmental variable. If it is present, CGI knows to get its arguments from the web browser.
Last Updated: Fri, 19 Nov 2010
Java Terminator: Cross-Platform Terminal Emulator
For years, I’ve been searching for a suitable terminal emulator for Cygwin, but nothing seemed as polished or had enough features to pull me away from the boring default.
I finally found the Holy Grail in a program I’ll call Java Terminator. The authors of this fine program just call it Terminator, but unfortunately a later Linux GNOME-based terminal emulator of the same name stole some of their thunder.
Last Updated: Fri, 05 Nov 2010
Using LWP::Simple to retrieve binary data
We have a Perl CGI script at work that acts as a proxy. It grabs a pkcs12 digital certificate file from an internal server and delivers it to a user through his or her web browser. The pkcs12 file is in binary format.
Everything worked fine until put the code on a new server. Suddenly, the
files downloaded by the web users were corrupted. We also began seeing the
following warning in the log files:
Wide character in print at download.cgi line 124.
Here is the code…
Last Updated: Fri, 16 Apr 2010
Installing ODBC on Linux
At work, we use Microsoft SQL Server and IBM AS400 databases. Here’s how I set our Linux boxes to allow them to connect to the databases through ODBC. There are seperate instructions for the Debian and Ubuntu (9.10 Karmic Koala) and Red Hat Enterprise Linux (RHEL4 and RHEL5) distributions.
ODBC connections require several layers of software to work. The bottom layer consists of the individual ODBC drivers for each database system. Our top layer is the DBI/DBD interface for Perl. In between these layers is the ODBC driver manager, which keeps track of the DSN’s and their corresponding ODBC drivers.
Packages and Software to Install
Ubuntu Version (tested on 9.10 Karmic Koala)
Debian Version (“unstable” distribution)
We use unixODBC as our ODBC driver manager. First, install unixODBC:
NOTE: Perl’s DBD::ODBC module requires the developer’s version
of unixODBC, so install that one.
# apt-get install unixodbc-dev
Last Updated: Tue, 09 Mar 2010
Things I always need to look up in Perl
Here are some random Perl things I always need to look up:
Last Updated: Mon, 21 Dec 2009
PNG Color Mismatch in IE7
Internet Explorer never fails to impress me in its ability to frustrate and complicate my web designs. The screenshot below shows a png image with a #3D6B99 background color over a div with the same #3D6B99 background color (specified in CSS).
The background colors don’t match! Of course everything looks fine in Mozilla Firefox. So what’s the problem?
Last Updated: Wed, 18 Feb 2009
Writing an Apache Module for RHEL 5
Recently, I was asked by my employer to write an Apache module. The module reads the requestor’s digital certificate and checks it against our database of active users. In this post, I’ll explain how to get started writing Apache modules, especially for Red Hat Enterprise Linux 5 (RHEL 5.2).
Last Updated: Wed, 14 Jan 2009
Debian Upgrade Woes
We run two Debian Linux servers at work: a back-up web server and a sandbox for random Linux development. Recently, I decided to do an apt-get upgrade on the servers to update their software packages to the latest versions.
I figured it would be simple. We were already running the unstable branch. And it hadn’t been that long since I last attempted an upgrade. So, as root, I issued the following commands:
# apt-get update # apt-get dist-upgrade
Uh-oh! I kept getting the following error:
Setting up libc6 (2.3.5-3) ... mv: error while loading shared libraries: libacl.so.1: cannot enable executable stack as shared object requires: Error 14
Last Updated: Thu, 17 Nov 2005
Javascript Support for Firefox
Making your Javascript code work on both IE and Firefox isn’t hard. Here are a few modifications to IE-only code to make it work on Firefox:
Last Updated: Thu, 17 Nov 2005
Incorporating Blosxom in an Existing Website
Here’s how I configured my website to use Blosxom as its CMS (content management system - a fancy term for the way a site is organized). My requirements were:
- The root URL (www.kcaran.com) had to point to blosxom.cgi.
- The URL’s to blog entries should look like static links (e.g., http://www.kcaran.com/entries/technology/linux/debian_upgrade_woes.html
- Files and directories outside of Blosxom should be accessible as before. My Fantasy Football pages should still reside at http://www.kcaran.com/footb/. And I should be able to create new files and directories without changing the web server configuration.
Once you have Blosxom configured and working the way you want, place
it in a directory named blosxom under your root web directory.
For me, that would be /var/www/caran/blosxom.
[caran@mlougee caran]$ pwd /var/www/caran [caran@mlougee caran]$ ll blosxom/ total 60 drwxrwsr-x 9 caran www-data 4096 Oct 7 14:17 ./ drwxrwsr-x 25 caran www-data 4096 Oct 7 14:27 ../ -rw-rw-r-- 1 caran www-data 14 Sep 29 08:57 .cvsignore drwxrwsr-x 2 caran www-data 4096 Oct 7 14:54 CVS/ -rwxrwxr-x 1 caran www-data 16784 Oct 7 14:17 blosxom.cgi* drwxrwsr-x 3 caran www-data 4096 Oct 5 12:29 css/ drwxrwsr-x 4 caran www-data 4096 Oct 7 13:41 entries/ -rw-r--r-- 1 www-data www-data 0 Oct 7 14:16 error_log.txt drwxrwxr-x 3 caran www-data 4096 Oct 7 14:54 feedback/ drwxrwsr-x 3 caran www-data 4096 Oct 7 14:23 flavours/ drwxrwsr-x 3 caran www-data 4096 Oct 4 14:34 images/ drwxrwsr-x 4 caran www-data 4096 Oct 5 12:30 plugins/
Last Updated: Thu, 17 Nov 2005
Using CVS in a Windows environment
Managing and tracking changes made to code, otherwise known as version control, is vital to any software project, large or small. CVS, the Concurrent Versions System, is one change management application. This is a summary of how to use CVS in an environment with servers running both Unix and Microsoft Windows operating systems.
Last Updated: Wed, 05 Oct 2005
Perl Modules Primer
Splitting a Perl application into seperate files can be trickier than doing it in other languages, like C or C++, but it is still an important part of producing maintainable code.
Creating the Package
A Perl module is a collection of code stored in a single file. By definition, all variables and function names in the module are stored in a package with the same name as the file.
For example, a module named Cgiutils would be stored in the file Cgiutils.pm. Any functions or variables in the module belongs to the Cgiutils package namespace. The beginning of the file should look like this:
Last Updated: Mon, 26 Sep 2005
Sending an email in HTML format using Outlook
For those of you lucky enough to use Microsoft Outlook for email, here’s how to send a message in HTML format:
Last Updated: Mon, 26 Sep 2005
Using Perl Under IIS
Some may consider me a masochist, but Perl is my language-of-choice for web applications, even when I am “forced” to use Microsoft’s Internet Information Services, otherwise known as IIS, for my web server.
As usual, the Microsoft server has little quirks that need to be tamed in order to write cross-platform code. Here are some tips for making your perfectly good Perl code run under IIS:
Last Updated: Mon, 26 Sep 2005
SQL Server: Padding of data in columns of type ‘varchar’
I’ve been having some trouble with the way Microsoft SQL Server pads strings stored in its tables with spaces. Generally, I would assume that columns of type ‘CHAR’ would be a fixed length (and therefore padded), while columns of type ‘VARCHAR’ would be variable length. But I would be wrong.
The default behavior for SQL Server 7.0 and Server 2000 is that CHAR’s and VARCHAR’s are padded to their maximum lengths. To make the VARCHAR columns unpadded, the ‘ansi_padding’ property needs to be set to ‘off’. Unfortunately, you must do this every time you open a session with the database server. There isn’t a way to force ANSI padding off as the default.
Last Updated: Mon, 26 Sep 2005