How I fixed git-grep macOS UTF-8 support
As a speaker of Greek, I’ve been fixing issues in the handling of non-ASCII characters for over 40 years, using techniques ranging from simple lookup tables to dynamic patching of in-memory images. Here’s how I debugged and fixed the handling of UTF-8 characters in the
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git grep command, which was broken for almost a decade.
The sorry state of software quality
Thanks to a tweet by Aaron Toponce I learned about the Linux
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/dev/full pseudo-device. Write system calls to it always fail with a
ENOSPC (no space on device) error. With it finding software that doesn’t check for failed writes is a piece of cake. Let’s see this in action.
Rather than alchemy, methodical troubleshooting
I recently encountered a pesky problem while trying to build a React Native project under Apple’s Xcode. The build would fail with an error reporting:
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EMFILE: too many open files, watch. Frustratingly, all available advice on the web pointed to different (often inexplicable) directions, none of which worked. After tormenting myself with these, I decided to troubleshoot the problem methodically, which allowed me to pinpoint it and solve it with an uncommon and noteworthy application of the git bisect command. Here’s the story.
The Evolution of the Unix System Architecture
Unix has evolved for more than five decades, shaping modern operating systems, key software technologies, and development practices. Studying the evolution of this remarkable system from an architectural perspective can provide insights on how to manage the growth of large, complex, and long-lived software systems. In 2016 my colleague Paris Avgeriou and I embarked on this study aiming to combine his software architecture insights with my software analytics skills. Here is a brief summary of the study, which was published this month in the IEEE Transactions on Software Engineering.
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Reviving the 1973 Unix text to voice translator
The early Research Edition Unix versions featured a program that would turn a stream of ASCII text into utterances that could be played by a voice synthesizer. The source code of this program was lost for years. Here’s the story of how I brought it back to life.
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Fast database UPDATE/DELETE operations
You may be familiar with the use of a database upsert of MERGE operation to insert a record into a table or update an existing record, if that record already exists. This evaluates the condition for finding the record only once, and is therefore more efficient than other alternatives. How can you efficiently handle a reverse operation of updating a record and deleting it if some condition holds?
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Raspberry Pi 400 vs ZX Spectrum
The release of the Raspberry Pi 400 personal computer reminded me of a wildly popular home computer that was launched in a similar computer-in-a-keyboard format almost 40 years ago: the Sinclair Research ZX Spectrum. I decided to compare the two, following the steps of an earlier comparison I performed between the 2015 Rapsberry Pi Zero and the 1957 Elliott 405.
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Error handling under Unix and Windows
One thing that struck me when I first encountered the 4.3BSD Unix system call documentation in the 1980s, was that each call was followed by an exhaustive list of the errors associated with it. Ten years later, when I was going through the Windows API, I was disappointed to see that very few functions documented their error conditions. This is a big deal.
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Shell scripting for software developers
In an open online edX course on Unix tools I was running over the spring with more than a thousand registered learners, I got asked for ideas on how shell scripts can be useful. This is an intriguing question, because the course focuses mainly on performing one-off tasks in the areas of software development, data engineering, and system administration, rather than automation through shell scripts. In response, I posted how shell scripting improves my personal productivity. Here’s my take on how shell scripts are employed in diverse software development tasks. I plan to post further installments on system administration and data analytics.
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IBAN length and DESI score
Looking at the formats of European country international bank account number (IBAN) codes, I noticed that the IBAN length didn’t seem to be significantly correlated to the country’s population. Could it be related to the country’s IT maturity? I tested that using as a proxy the EU Digital Economy and Society Index, and the results were stunning.
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