Indholdsfortegnelse for September 2023 i Linux Magazine

Debian developers have a habit of writing utilities for maintaining distributions that are also useful for ordinary users. For example, diffoscope [1], which compares binary files, is useful for both version control and comparing – among others – PDF and LibreOffice files. In the past year or so, an equally useful utility called debvm has emerged. As the name suggests, debvm [2] is a tool for the quick and easy creation of virtual machines (VMs) running Debian releases and architectures [3]. While debvm gives developers the ability to test releases and architectures without changing hardware, it can be also be useful to any user as a sandbox for testing scripts or checking the results of mixing repositories. Where traditional virtualization methods such as VMware, VirtualBox, or Gnome Boxes create permanent…

When implementing my greenhouse control system, I didn’t have to start completely from scratch. An older control system already existed with which I had a little experience. Building on this established setup, I decided to use power windows for the hinged skylights (Figure 1) and a fan to circulate the air in the greenhouse. Also, when nighttime temperatures dropped in the spring and fall, I wanted a heater to switch on automatically. In contrast, crops needed protection against excessive heat in summer. An intelligent control system would also be nice to reference the outside temperature, allowing it to close the windows in time for cool evenings and build up a heat reserve for young crops during the night. At the same time, a reliable clock was essential to adapt to…

We looked at the brilliant Magic Wormhole some time ago. It’s a command-line tool that sets up an encrypted peer-to-peer file transfer between your machine and any target machine out in the wilds of the Internet. For this to work, a network’s NAT needed to be negotiated, as did any firewalls, and the connection itself needed to find a way to talk to the destination. But Magic Wormhole handled all of this transparently, with users needing to do little more than type send followed by a path to a file, or receive, followed by a code the sender is shown. It was brilliant, and still is, for one off ad-hoc transfers. But Magic Wormhole still requires a little command-line knowledge. While this isn’t something that will likely bother Linux users,…

There’s a noticeable trend that is almost tracking the trajectory of command-line use, albeit a decade behind: the move away from cloud-hosted services. This may be because many of us now have enough network capacity at home, are willing to set up our own servers, or perhaps pay for a micro-service site for running a few web applications. But there are significant advantages in going your own way, not least of which is knowing you’re in control of both your own data and your own support destiny. It frees you of any nagging doubts about privacy, or a service being withdrawn, and puts you back in control of your personal information. It’s why wallabag is so popular for caching web pages, and why Tiny Tiny RSS is still going strong…

We’ve looked at quite a few ebook readers in these pages. We like them because they always have a focus on beautiful text rendering, removing distractions, and simple design. They’re a great solution if you ever need to read a substantial ePub or MOBI document on your desktop, but the desktop experience is always inferior to the experience offered by an E Ink reader. E Ink displays, such as those found on Amazon’s Kindle or Kobo’s Nia, are a lot kinder on your eyes, look much more like a paper book, and remain mostly distraction-free by being terrible Internet devices. But most E Ink readers, especially the Kindle, are deeply proprietary and offer little in the way of customization. Which leads us back to the Linux desktop. Or does it?…

If you prefer your games scrolling in all directions rather than just one, Jumpy is for you. It’s a manic multiplayer brawler played on 2D platforms under the sea. The brawler part means it’s your job to hit other players with whatever you have at hand, including your fins, or any weapons you find within the level. The level will zoom and scroll around to follow you, and the action is quick and reflexive. It’s a little like the arcade-classic Bomberman with sabres and pistols rather than bombs. But the game also describes itself as “tactical,” which means the best strategy is to use platforms in the background, rather than to simply hunt and chase your enemies. Up to four players can take part, with local play supporting two from…

Side A (32-bit Boot) Explore the world of small distros! This disc boots as a Live system to Tiny Core 14.0. Or, mount it as a filesystem to discover the following ISOs in the top directory. Copy an ISO to your hard drive to boot it from VirtualBox, or burn it to a boot medium to boot directly. • CorePlus-14.0.iso (248MB), http://tinycorelinux.net/• S15Pup32-22.12-230708.iso (382MB), http://downloads.sourceforge.net/spup/• S15Pup64-22.12+4-T.iso (420MB), http://downloads.sourceforge.net/spup/• TinyCore-14.0.iso (23MB), http://tinycorelinux.net/• TinyCorePure64-14.0.iso (31MB), http://tinycorelinux.net/• alpine-extended-3.18.2-x86.iso (762MB), https://www.alpinelinux.org/• alpine-standard-3.18.2-x86_64.iso (189MB), https://www.alpinelinux.org/• antiX-22_x64-full.iso (1.4GB), https://antixlinux.com/• dsl-4.4.10.iso (50MB), http://www.damnsmalllinux.org/• fossapup64-9.5.iso (409MB), https://distro.ibiblio.org/puppylinux/puppy-fossa/ Side B (64-bit) The backside of this month’s DVD boots to SystemRescue 10.1. Or, if you mount it as a filesystem, you’ll find the following virtual appliances in the top directory. Copy these files to your hard drive to import a…

Quick, name three Linux distributions: You probably thought of some of the big players, such as Ubuntu, Debian, openSUSE, or Red Hat. What they have in common is that they target current desktop and server hardware, and they provide huge (yet similar) selections of current Linux applications, covering all categories, including office, multimedia, development, and gaming. Typically you download a large DVD ISO image and write it to a USB stick – or burn a DVD if you still have a DVD drive – then boot it and launch the installer. All of these modern general-purpose distributions let you reassign disk space and create a boot menu from which to select the new OS from a menu of systems installed on the hard disk. If you think of Linux as…

Installing Debian 12, codenamed Bookworm, I was struck by how much the distribution has changed in the 24 years since I first installed it (Figure 1). Around the turn of the millennium, Debian already had a formidable reputation. It was one of the half dozen leading distributions, but it was widely viewed as an expert’s choice, and its developers were viewed as members of an elitist club obsessed with radical forms of governance. In fact, I once heard Eben Moglen, the lawyer behind the GNU General Public Licenses, describe the project as an example of syndicalist anarchism in action. By contrast, in 2023, Debian has mellowed, quietly becoming more accessible, with even its once notoriously vicious mailing lists functioning more responsibly. Part of the reason for the change may be…

Computers crash. Whether because of human error, software bugs, or hardware dying from old age, workstations and servers alike will eventually break. For this reason, every system administrator should have a digital first-aid kit to get broken systems back to working condition as soon as possible. For this task, I keep SystemRescue in my toolkit. SystemRescue, formerly known as SystemRescueCd, is a Live Linux distribution designed to repair broken systems and handle a number of maintenance tasks. It includes tools to recover deleted files, repair broken boot managers, fix inconsistent filesystems, and more. The default set of installed programs is impressive (see Table 1 for a sample of included tools or visit the SystemRescue website [1] for the complete list). If one of your workstations or servers is rendered unbootable,…

The times when the preferred source for an application was a distribution’s own archives are definitely over for the majority of users today. In addition to third-party repositories, Flatpaks, AppImages, and snaps, the average user’s filesystem also hosts PIP (Python), Cargo (Rust), npm (Node.js), or Homebrew (macOS) based installations. All of these installations bypass the operating system’s update mechanisms, forcing you to update them separately. One way out of this uncomfortable situation is the Topgrade package manager. Topgrade was recently abandoned by the original developer after five years [1], but the community is now continuing to maintain the tool as Topgrade-rs [2]. For simplicity’s sake, I will simply refer to the community fork of the tool as Topgrade in this article. One for All Topgrade promises to launch all package…

Artificial intelligence (AI) is on everyone’s minds, not least because of chatbots and the ChatGPT text generator. Of course, the capabilities that AI has developed go far beyond chats with a chatbot on countless websites. For example, AI can be used to process acoustic speech signals, and it is the precondition for autonomous driving. Some applications – and generating AI models – require computers with powerful processors and a generous helping of storage space and RAM. Small computers like the Raspberry Pi, on the other hand, are more likely to benefit from ready-made methods and applications that draw on AI for their implementation. All of these processes are founded on machine learning (ML), which itself is based on self-adapting algorithms that process information from reference data. Deep learning, as a…

One episode of the award-winning TV series Futurama depicts the Internet as a metaverse in which advertising banners attack users’ avatars like birds of prey: “The Internet! My God! It’s full of ads!” Even without a metaverse, Internet users today are tracked by trackers and cookies and flooded with unwanted advertising. But users can protect themselves against this flood of advertising. There are various methods of evading tracking by advertisers, confusing trackers, and keeping unwanted content out of websites. With the help of the free Pi-hole [1], this article looks at a couple of effective approaches that help protect you against unwanted content at the server, network, and client levels, while minimizing the threat of phishing at the same time. Proxy Filter with Problems In the early 2000s, the proxy…

Image metadata is common, especially for photos. Most photo processing applications will have a panel showing exposure, focus, date, location, and dozens of other attributes, all of which are written into the file as metadata when a photo is taken. Metadata like this can even be viewed and edited on the command line, with utilities such as exiftool. But we don’t often consider that audio files include a similar set of data related to their production. This data includes album names, track sequence, recording data, artists, and many other optional attributes. A few of these might be displayed by your audio player of choice, but it most likely won’t let you edit this data. The tone command-line tool helps with this. With tone, you can parse audio metadata in bulk…

JSON is the JavaScript Object Notation format, used by JavaScript programmers to describe data structures within an easily readable text format. Of course, JavaScript programmers still use JSON, but the format long ago escaped the confines of web-based client-side programming to become a “commonly used data interchange format,” alongside YAML, XML, and even CSV. As a result, many API and command-line tools, alongside vital infrastructure such as journald, can output text-based data as JSON so that it can more easily be interpreted by another programming language while still making sense to humans. This is great for machines, but not so brilliant for humans, and it’s the life of the JSON-loving human that this brilliant little utility wants to make easier. The problem with JSON is that while it is readable…

For a special job, you need a special tool. Occupying a special place beside the grand old generalists are a number of Linux distributions that have a very narrow focus, such as audio, gaming, or security. Specialized Linux distributions come in all sizes, but even the huge ones often fall into the “lightweight” category, because, even though they might need a lot of space for their specialist tools, they don’t have to make room for all the other general-purpose software you’re used to seeing in a Linux system. Hundreds of specialty distros exist in the wild. This article highlights a few popular alternatives (Table 1). I’ll introduce you to Daphile, an audio server; Linux From Scratch, an educational roll-your-own Linux; Recalbox, which lets you run classic games on EmulationStation; System-Rescue,…

If pollsters asked for the Linux word of the year for 2022, “immutable” would definitely make the short list. The term, referring to an immutable filesystem, shows up wherever the topic turns to distributions. The technology is by no means new, but has not seen much use thus far. For several years, the major commercial Linux vendors such as Red Hat and SUSE have been preparing for a paradigm shift with their enterprise software, focusing on protection both against unwanted intruders and against operating errors or systemic defects. A remedy against imponderables like this is a read-only filesystem mounted at boot time. However, this type of system also changes the format and method of delivering software and the package manager’s position as a central component of a distribution. Immutable filesystems…

Math helps us to make sense of the world and make it a better place. The language of math (formulas and equations) is universal, but it is also universally difficult to render handwritten formulas into digital form for the computer. Thirty years ago, math graduate students would pay programmers to render their beautifully drawn mathematical formulas for the computer because the process took twice as long as the original drawing, regardless of the available software. Even today, entering a complex mathematical formula can be much slower than writing the same formula by hand. MathLex [1], a little-known JavaScript utility, helps solve this problem. It parses math input notation into a syntax tree and then renders the notation as several target outputs, which you can then use on your web pages…

To keep your data under your control, instead of outsourcing to unknown servers, the typical approach is to simply host the services yourself. It is becoming increasingly easy for less technically inclined users to operate a small home server. Not least, the Raspberry Pi has contributed significantly to this by encouraging many users to experiment. The choice of suitable hardware is naturally far greater: from devices such as laptops or PCs that have already been replaced by newer gear to virtual machines to rented VPS servers on the Internet. To save you from having to package and configure every service as a container yourself, the number of home server managers have increased recently. Examples include DietPi, YunoHost, Mistborn, or NethServer. The summer of 2022 saw the release of another alternative…

There are many disk usage tools, so it requires something special to pull me out of my du dependency stupor. I looked at one called Parallel Disk Usage recently, because it was very quick, and erdtree is just as quick and takes a different UI approach. Where Parallel Disk Usage outputs a bar graph showing usage for every directory, erdtree’s erd command will instead collate totals in the same way du does. It also offers many of the same command-line options as du, including a human-readable option and long output, so it’s a great drop-in replacement – and it does all this while looking much better than du. The default layout takes inspiration from another perennial command, tree, with ASCII lines branching off from directories to subdirectories. The number of…

The fzf fuzzy finder has changed the way many of us search for things from the command line. In particular, it helps when you can’t remember exactly what it is you’re looking for or can only remember a certain path. It works well on its own like this, but it works much better when it’s integrated into your a shell for file and history search, or within an editor such as Vim for searching documents. Codespelunker, run from the command line as cs and easily installed via go install, is another great alternative and is better suited to finding things within files without resorting to piping things through grep. This is because it’s more like both a Google search and search result page embedded into your console for local searching,…

Despite the scale of many modern games, with budgets in the hundreds of millions, and hundreds of people working on them for years, there’s nothing quite like a lone coder’s simple adrenaline-fueled shooter. Antsy Alien Attack Pico is a great example of one of these, having been developed by Martin Wimpress for the Linux Game Jam 2023 using PICO-8. We’ve covered PICO-8 before, a brilliant platform for game development that enforces strict limitations, just as a simple fictitious early 1980s games console might. Those limitations include a display of only 128x128 pixels with 16 colors, simple 4 channel audio, and just 32KB of storage. The hope is that it allows game developers to put their focus and efforts into pure gameplay, and – as with Antsy Alien Attack Pico –…

Few photographers are aware that Krita, the popular painting program [1], can also be used to edit photos. Considering that many illustrators and graphic designers use Photoshop or Gimp for digital painting and drawing, this is not surprising. In fact, Krita’s approach is identical to that of classic layer-based image editors in terms of the basic functions. However, it has several pretty significant advantages compared with Gimp. On the one hand, Krita lets you edit photos in large color spaces like Adobe RGB. This is especially important if you want to print a high-quality image with intense colors. On the other hand, Krita has filter masks, a counterpart to Photoshop’s adjustment layers. They allow for far more comfortable image editing, because numerous effects can be adjusted retroactively and masks can…