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…

I carry a Garmin Etrex 10 when I go bug-collecting. It's a handheld GPS receiver without many frills, and I only use it to record the latitude and longitude of each of my collecting sites as a waypoint. At the start of a field trip I delete all previous waypoints. When I do this, the trip's…

I've written several BASH scripts that use GNU AWK's printf function to round off decimal numbers. Now I've learned that the rounding is biased, and I need to re-do the scripts. For me the desirable way to round off a decimal is to round up if the bit to be discarded is greater than one half, and…

SANITY WARNING: Please don't read this article unless you're a compulsive shell scripter, like me. Seriously. There are some excellent FOSS sequence viewers in the distro repositories, with great GUIs and lots of features. Why would you want to build a less capable viewer that only works in a…

When cleaning UTF-8 text files I sometimes come across invisible characters that I call 'gremlins'. These aren't the usual non-printing characters, like whitespace and (horizontal) tab, which are non-printing characters I expect to find in the plain text files I work with. Gremlins are weird things…

In this article I've pulled together some command-line tips for alternating lines of text. Questions about alternating lines turn up regularly on online help forums, and they sometimes get complicated answers. Here I've tried to keep things simple. Interleaving lines For demonstration purposes I'll…

It took me a fair while to get comfortable with the ISO 8601 date format. After so many years of using DD MMM YYYY, my old eyes and brain had some trouble understanding YYYY-MM-DD. Finally something clicked, and I now read 'ISOdates' easily and I really appreciate their advantages. The biggest…

In 2003 a strange paragraph made the rounds on email. It read: Aoccdrnig to rscheearch at an Elingsh uinervtisy, it deosn't mttaer in waht oredr the ltteers in a wrod are, olny taht the frist and lsat ltteres are at the rghit pcleas. The rset can be a toatl mses and you can sitll raed it wouthit a…