Until recently, I was content using the Uncomplicated Firewall that comes built-into Ubuntu. And it's called uncomplicated for a reason: its complicated counterpart – the iptables. It's not to say that iptables are difficult to comprehend or even impossible to use, but is rather massive. In other w…

A non-breaking space (NBSP) is a special kind of whitespace. It's an invisible signal that tells a text-processing program to avoid replacing that space with a linefeed or carriage return. For example, if you wrote "2 kg" in LibreOffice Writer and didn't want the "2" to be at…

There's always more than one way to do a job in the shell, and there may not be One Best Way to do that job, either. Nevertheless, different commands with the same output can differ in how long they take, how much memory they use and how hard they make the CPU work. Out of curiosity I trialled 6…

In part 1 of this article I showed how I used AWK on the command line to work up daily rainfall data for my home town, Ulverstone in Tasmania. I wasn't ready to analyse the data, because there were quite a few missing-data days. Some were part of accumulated-total series, where the rainfall total…

AWK is my tool of choice for processing plain-text data, so when I wanted to look closely at daily rainfall data for my home town, I fired up a terminal. In this two-part article I explain how the rainfall data were beaten into shape, mainly with AWK, so I could do my analysis. The commands shown…

I was preparing a slide presentation and wanted to show a block of random 8-bit bytes, like this: Naturally I didn't just type out that block of text on a slide, which would have taken maybe 10 minutes, or copy and modify some byte-text I found online. Of course not. Instead I spent hours dreaming…

In my data-cleaning work I often make up tallies of selected individual characters from big, UTF-8-encoded data files. What's the best way to do this? As shown below, I've tried grep/sort/uniq, AWK and Ruby, and AWK's the fastest. The trials also revealed an unexpected problem with the uniq program…

I've just built my own GUI calculator (script below). OK, you're probably thinking "WHY? There are plenty of perfectly good GUI calculators for Linux. Why build another one?" And my answer is "Because the available calculators are way too powerful and don't do what I want…

You might be surprised to learn that there are programs for running presentations in a terminal. No, I don't mean opening PowerPoint or Impress slides one after the other, as images in a frame-buffered console. I mean presenting slides coded for the terminal, in a terminal. Interesting idea? It…

My wife has been in the same Scottish Country Dancing group for many years, and back in 2005 she began keeping a record of the dances done at each meeting. She lists a fair bit of information in her "dances done" spreadsheet (screenshot below). She recently asked me "Would it be…