Inhoudsopgave van July 2021 - Linux Magazine

Not only are brain teasers fun, they also promote logical thinking skills. The PC has long since replaced the good old puzzle book, making memory training far more efficient with more flexible tasks. Gbrainy, a puzzle game originally developed for the Gnome desktop, is a fun way to train your memory. Gbrainy includes numerous logic games from different areas. The application, which can be used across all platforms, trains both your memory and your mental arithmetic skills. The games are divided into categories (Figure 1), with three difficulty levels for each category, which lets users advance to a higher difficulty level after practice. The program also keeps a success log for each user, and if so desired, a help function is available for solving tasks. On the Record Gbrainy can…

Open a paper, turn on the radio or TV, and you are confronted with statistics concerning the spread of COVID-19. Sometimes, it’s hard to wrap your mind around all the data, and even then, you are never sure if the media is taking the data out of context. For instance, a report of 30,000 new infections in a country doesn’t provide any information about the number of tests or the positivity rate. If you want to drill down into the data concerning the spread of COVID-19, you can use gawk scripts and simple shell commands to process, evaluate, and present these statistics in a more meaningful way. A Few One-Liners The statistical data on the spread of COVID-19, usually collected daily and organized in timelines, is freely available on the…

I still remember a traumatic event as an elementary school student: A weekend newspaper had set a logic puzzle for kids, the solution of which it promised to publish in the next issue a week later. It involved a bathtub with two taps: one of which filled the tub in 10 minutes, the other in 15. The question was how long would it take to fill the tub if both taps were turned on all the way. As a little boy, I was absolutely sure that 10 plus 15 equals 25, which is 25 minutes. My father laughed and suggested that couldn’t be true, because two taps would fill the bathtub faster than one alone. The next weekend, I was initially triumphant, because there it was – printed in black…

Pixel shaders are amazing. They’re perhaps the closest modern technology we have to the custom graphics processors and coprocessors found in many of those 1980s home computers. Shaders came to life as self-contained functions that helped 3D surfaces look better, such as the simplistic Phong or Gouraud shading you might be familiar with from the original Blender. Pixel shaders are also distinct from the ray tracing or light casting that goes into building a scene, because, as their name describes, they operate on the final pixel, dynamically changing their color according to their position within the environment. This is why most are considered post-processing effects that can be applied to any scene or game after the main artwork has been added. Rather than shaders being calculated by your CPU, they…

The Internet has grown to become a huge distraction. The content generation and dynamic linking algorithms on domains like Facebook, reddit.com, YouTube, and Google are purposefully designed to keep you engaged and looking at the screen, tracking your Internet use while surreptitiously inserting discrete advertising. But it wasn’t always like this. The early World Wide Web was designed to be rich in accessible and portable content, augmented at the time by a host of other protocols that provided alternative ways of retrieving information. One of these protocols was Gopher, a prototype web that was contemporary with Tim Berners-Lee’s HTTP, but easier to deploy and access. It provided a simple and navigable way to present a collection of documents and even jump between them. It was a perfect way of accessing…

At first glance, Minetest looks like a clone of the now venerable Minecraft, and to some extent it is. It features voxel graphics, there are both creative and survival game modes, and there’s a huge modding community of people that spend their time designing and building unique environments within the game. All of this will be familiar to Minecraft players. But Minetest offers much more than this. It’s open source (unlike Minecraft, which despite Notch’s early promises is not), and this means that you can invest your time in the code and the game engine sure in the knowledge that it won’t become redundant when development drops or moves to a different platform. The Minetest community has fully embraced this, creating many of their own games, mods, and textures, many…

Ubuntu 21.04 64-bit This month’s DVD features the latest versions of two major distributions. First up is Hirsute Hippo, otherwise known as Ubuntu 21.04. The Ubuntu team chose a hybrid desktop environment of Gnome 3.38 and Gnome 40, so much of the interest in this release is in security enhancing features. Ubuntu tried using Wayland as the default display server in the 17.10 release, only to encounter difficulties and return to the X Window System. Now, with Ubuntu 21.04, Wayland is once more the default. With better performance and high security, Wayland is a long-awaited change, although recording and screen capture apps may not work. Fortunately, switching to X Window is a minor task. Other security features include a power mode option for laptops and a recovery key option for…

The flash card is still one of the most effective methods for anchoring learning material in long-term memory. But instead of working with a physical index card box and decks of flash cards, today’s students use computer programs. Anki [1], considered to be one of the most innovative learning programs for electronic flash cards, goes far beyond everyday needs and even offers a web-based counterpart. Anki includes several convenient features that you won’t get when shuffling through an old-school stack of note cards, such as built-in statistics to chart your progress. The program also lets you rate your success with individual cards, keeping the most difficult at the front of the deck for additional repetitions. The Anki: flashcard system also comes with a large number of add-ons that let you…

A precise description of a complex problem is sometimes difficult to achieve. Plain text will work eventually, but it often requires a great deal of imagination on the part of the reader. In a conventional classroom setting, an instructor might attempt to illustrate a topic by drawing on a chalkboard or whiteboard during a lecture, but it is fair to ask whether the power of the computer might offer a better option than a professor talking and writing at the same time. Presentation tools such as Impress or PowerPoint evolved as a way to illustrate key concepts in advance, but these tools typically have limited support for mathematical expressions, and they tend to present information in a static, slide show format. Movies and video sequences, on the other hand, can…

Privacy isn’t just a thing you add at the end. In the best case, privacy starts with a set of guiding principles – a philosophy you build into the infrastructure from the ground up. The big social networking companies put all your data on a server, and that server is the site for all the data mining and other monkey business that comes with commercial social media. But, contrary to what you might hear from the giants, social networking doesn’t even need a server. Several free tools offer instant messaging and other social services in a peer-to-peer context. This month we look at peer-to-peer messaging with the Tox protocol, and we study some of the leading client apps for configuring and using Tox services. Also in this month’s Linux Voice,…

Linux users are spoiled for choice when it comes to many types of software. That’s especially true for text editors. When I first started writing this article, I tried to count as many editors as I could just off the top of my head. I stopped when I got to around 32. Quite a few of those editors run at the command line. While I’ve used several, I’ve never had great relationships with command-line text editors. I’m not sure why that is. Maybe it’s just we don’t have enough in common with each other to form a strong bond. Recently, though, I was working with a command-line application that played better with terminal text editors than with graphical ones. So, I duly set my default editor to the venerable GNU…

Shortwave is a perfectly named Gnome application. As its FAQ explains, the name comes from shortwave radio signals that, because of their long reflection properties and transmission distances, many of us will know from radio receivers before the digital age. Pre-Internet, a shortwave radio was a gateway to a world of international radio stations, letting teenagers anywhere listen to music from different continents or even from the middle of the ocean when it came to pirate radio in the UK. This Gnome application lets you do the same, albeit with the convenience of digital reception, 25,500 preset stations, and a complete lack of static noise from solar flares. The trade-off of access to such a huge curated list of stations is that they’re grabbed via API from radiobrowser. info and…

We can all agree that the Linux command line is wonderful. It’s often easier to use than the desktop, because it lets you do all kinds of things without the mental burden of coordinating pointer movement with multiple clicks across different panes and windows. Instead, you can construct simple commands to do simple jobs, one at a time. Creating folders, moving files, searching for things, and editing configuration files can all be done easily. But when you want to do more than one thing at once, it can then sometimes become easier to use the desktop. One reason for this is that the command-line tools that can help, such as pipes with the “|” symbol, are a little difficult to use, and you can’t always be confident about what will…

This is a wonderful piece of software that has a couple of specific hardware requirements. You will need Valve’s SteamVR with a supported virtual reality headset, and perhaps most challenging at the moment, a reasonable graphics card. But Open Brush is easily worth the effort. It’s best described as an immersive sketching and drawing tool where you, the artist, draw in the three-dimensional space around you – just as you might by drawing an imaginary line in front of, above, and around you. For many years, it was a commercial Windowsonly product called “Tilt Brush,” purchased from the original engineers by Google. Its development corresponded with Google’s big push into VR, first with Cardboard and then with Daydream, between 2016 and the latter’s cancellation at the end of 2020. But…

First released in 2009 by brothers Artyom and Kyrill Zorin, Zorin OS [1] quickly became known as a Debian-derivative with a minimalist desktop interface based on Gnome. Today, Zorin continues to tweak its desktop, but has also become known for its appeal to new users – particularly for its Zorin Appearance app, which in some editions emulates the design of other operating systems, including Windows 10 in Zorin 16 [2]. In addition, Zorin 16 also supports a wide variety of installation methods, ranging from apt and Wine to Snap and Flatpak. In a break from this column’s normal format, I interviewed Artyom to find out more about Zorin OS, including its past, present, and future. Linux Magazine (LM): How did you and Kyrill get involved with free software? Artyom Zorin…

In most Linux distributions, the files associated with the OS end up in specific places. Most Linux distributions subscribe to the filesystem hierarchy defined in the Linux Standards Base (LSB), which specifies the familiar directory names you are accustomed to if you work in Linux (/etc, /dev, /bin, etc.). On most Linux systems, if you do not have the files in the right places, the applications will not find them. But experimentation is at the heart of Linux, and every rule has an exception. An innovative project called NixOS [1] takes a different approach to system configuration and package management. On NixOS, all files are in the Nix store. For applications to find them, NixOS links to the correct locations with symlinks. This approach makes all kinds of things possible.…

What is causing the smart home hype? Do you really need socket outlets that can be switched on by your cell phone, and if so, what is it all good for at the end of the day? Starting a Raspberry Pi project to find the answer to such questions has always proved to be a workable approach, thus far. Even if my answer to the “Do I need it?” question was, “No,” one thing is for sure, open source and Raspberry Pi can do it. Of course, a targeted solution needs to meet a number of criteria. It should be based on standards for which sufficient numbers of different components exist, while being open source. All components need to harmonize with the Raspberry Pi, work as self-sufficient systems without any…

The popular messaging application WhatsApp has recently alienated many users with its new terms of service and privacy policy. It’s a situation that once again illustrates that when you put yourself in the hands of a proprietary service, you put yourself at the mercy of the operator. If you are dissatisfied with a change, either you grudgingly continue using the service, or you move to a different application with similar features. In the case of WhatsApp, there are quite a few alternatives, and many were suddenly overrun with WhatsApp users looking for another option. This article looks at the different categories of messaging services, and then delves into one particular option – using peer-to-peer messaging apps based on the Tox protocol. Open Source Clients Signal [1], Threema [2], and Telegram…

Dig is one of those perennial Linux commands that many of us have used at some point to help fix a network issue. It’s a relatively simple command that can query a DNS server in the same way a web browser does, asking the server for the IP address associated with a specific domain name. It’s usually the first thing to try when your browser can’t load a few unassociated web pages but you can still ping IP addresses. Typing dig followed by the domain name, for example, will query your configured DNS and return whether one or more answers were received and what addresses they return, alongside their response times. More than one address could indicate a load balancing system or addresses that differ according to your geographical location…

We often recommend the tool Wormhole for informal file sharing between machines. It uses end-toend encryption and can be easily installed by both parties. It’s as easy to use as sharing a temporary passphrase through a secure channel. But it’s also very basic in the features it provides, and it’s relatively unproven. We recently looked at a far more ambitious solution, Retroshare, which adds all kinds of secure communication channels, such as chat and forums, alongside its file-sharing functionality. It also supports Tor for maintaining online anonymity. But it is probably over-engineered as a replacement for Wormhole, which is where OnionShare might help. OnionShare is an application that helps you spin up one or more secure communication channels over Tor and promises to keep your data 100 percent safe and…

There are quite a few retroorientated games development frameworks, such as the proprietary Pico-8. These typically exist to artificially impose some of the restrictions of old hardware, such as a low resolution and color palette, to help foster creativity. They’ve produced some amazing results. GB Studio is similar but differs in one important way: The restrictions it imposes aren’t artificial but required, because the resultant binary from your game design is intended to run on a bona fide 1980s-era Nintendo Game Boy 8-bit console. The main application even includes a play button to preview your project on an integrated Game Boy emulator so you can be sure it will work. This may seem like a crazy idea, but there’s a booming cottage industry in building games for old hardware, both…