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2010.01.12

Useful Polyglot Code

Four years ago I blogged about an incantation that would allow the Windows command interpreter (cmd) to execute Unix shell scripts written inside plain batch files. Time for an update.

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Last modified: Tuesday, January 12, 2010 7:52 pm

2009.12.27

How to Get a Glowing Recommendation Letter

Students who do well in my courses often come to me asking for a recommendation letter for graduate or postgraduate study. I only write letters for students I know well and I can honestly recommend, so some end up with a glowing recommendation while others leave empty handed. While I was drafting a few letters today, it occurred to me that obtaining a good recommendation letter is a lot easier if you've planned for it well in advance.

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Last modified: Sunday, December 27, 2009 6:53 pm

2009.11.25

The Risk of Air Gaps

As some readers of this blog know, from this month onward I'm on a leave of absence from my academic post to head the Greek Ministry of Finance General Secretariat of Information Systems. The job's extreme demands explain the paucity of blog postings here. I'll describe the many organizational and management challenges of my new position in a future blog post. For now let me concentrate on a small but interesting technical aspect: the air gap we use to isolate the systems involved in processing tax and customs data from the systems used for development and production work.

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Last modified: Wednesday, November 25, 2009 6:30 pm

2009.10.21

Basic Etiquette of Technical Communication

Parents spend years trying to teach their children to be polite, and some of us had to learn at school how to properly address an archbishop. Yet, it seems that advice on courteousness and politeness in technical communication is in short supply; most of us learn these skills through what is euphemistically called “on the job training.” With enough bruises on my back to demonstrate the amount and variety of my experience in this area (though not my skill), here are some of the things I’ve learned.

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Last modified: Sunday, December 27, 2009 6:43 pm

2009.10.15

Tags for Bibliography References

I love writing my papers in LaTeX. Its declarative style allows me to concentrate on the content, rather than the form. I even format the text according to the content, keeping each phrase or logical unit on a separate line. Many publishers supply style files that format the article according to the journal's specifications. Even better, over the years I've created an extensive collection of bibliographies. I can therefore use BibTeX to cite works with a simple command, without having to re-enter their details. This also allows me to use style files to format references according to the publisher's specification. Yet, there is still the problem of navigating from a citation to the work's details. Here is how I solve it.

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Last modified: Thursday, October 15, 2009 9:25 am

2009.09.16

Applied Code Reading: Debugging FreeBSD Regex

When the code we're trying to read is inscrutable, inserting print statements and running various test cases can be two invaluable tools. Earlier today I fixed a tricky problem in the FreeBSD regular expression library. The code, originally written by Henry Spencer in the early 1990s, is by far the most complex I've ever encountered. It implements sophisticated algorithms with minimal commenting. Also, to avoid code repetition and increase efficiency, the 1200 line long main part of the regular expression execution engine is included in the compiled C code three times after modifying various macros to adjust the code's behavior: the first time the code targets small expressions and operates with bit masks on long integers, the second time the code handles larger expressions by storing its data in arrays, and the third time the code is also adjusted to handle multibyte characters. Here is how I used test data and print statements to locate and fix the problem.

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Last modified: Wednesday, September 16, 2009 9:44 am

2009.09.02

Job Security

My colleague, who works for a major equipment vendor, was discussing how his employer was planning to lay off hundreds of developers over the coming months. “But I’m safe,” he said, “as I’m one of the two people in our group who really understand the code.” It seems that writing code that nobody else can comprehend can be a significant job security booster. Here’s some advice.

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Last modified: Wednesday, September 2, 2009 3:35 pm

2009.08.28

The Price of Cheap Labor

The strange entries I've found over the past two weeks I've been researching a large database are innumerable. Some addresses, like Wastington, DC are simply annoying, while others, like Vancouver BC V6T 1Z4 United States, are mildly amusing. It's clear to me that the database has been populated by the massive application of a cheap labor force. This is happening all too often, and I think it is a mistake.

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Last modified: Friday, August 28, 2009 6:32 pm

2009.08.27

Real Heroes

I always admired the pilots of the two PZL M18B "Dromader" fire-fighting airplanes that were stationed in Cephallonia's airport.

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Last modified: Thursday, August 27, 2009 4:28 pm

2009.08.20

HP-200LX Remote Control Hacks

All my friends know that for the past 15 years I've been semi-attached to an HP 100LX palmtop PC (recently updated to a 200LX) for my personal information management and many other tasks. The device is extremely versatile, sturdy, and flexible. Amazingly, after so many years of hard daily use, I still find new applications for it.

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Last modified: Friday, August 21, 2009 0:27 am