Linux Format的April 2021目录

Jonni Bidwell Grafana is fancy and all, but I’m pleased that my Pi generates graphs from CSV files with Gnuplot, then displays them on a TFT screen. It’s amazing how even though you’re only dealing with 240 pixels, hours can be spent tweaking the axes and layout to make them look just right. Nick Peers I’ve just built an Ubuntu-powered server for media-streaming duties. I want to run it headless, so have installed the brilliant Cockpit ( sudo apt install cockpit -y ) to monitor it via my browser. I can keep it up to date, access a Terminal and run Docker containers easily, too. Les Pounder Because I own a rather elderly desktop machine, I need to keep an eye on my resources and so I used bashtop to…

"We’ve started getting lots of enquiries about Azure. (Tiger Computing is are a Linux support and consultancy business.) So why the interest in Azure? Microsoft itself says “Linux is the fastest growing platform on Azure” and “Linux based images comprise 60 per cent of Azure Marketplace Images”. This shows Microsoft has embraced Linux – or that Microsoft customers have embraced Linux. It also reveals that Microsoft doesn’t care whether you use Windows or not. Microsoft has three revenue streams: Productivity and Business Processes (mostly Office 365, LinkedIn and Dynamics, its CRM offering); Intelligent Cloud (Azure, Github, SQL Server and Windows Server), and More Personal Computing (Windows, Surface device, gaming). Precious little of that is tied to Windows. I don’t know whether Office 365 is hosted on Windows servers or Linux…

Android 10 has been ported to the RISCV-based XuanTie C910 cores, and impressively it runs with working graphics and even touchscreen support. A video of Android running on RISC-V has been posted on the project’s GitHub (see http://bit.ly/LXF274Android10), where you can see the performance. It’s not great – you’ll notice it runs slower than modern smartphones – but it’s certainly promising and could pave the way for RISC-V-based Android devices in the future. RISC-V, in case you don’t know, is an open standard instruction set architecture used in many open-source processors and SoCs (System on Chips). You can find out more at https://riscv.org.…

Linus Torvalds announced the release of Linux 5.11, just in time for Valentine’s Day 2021. In his announcement, Linus noted that just because it was Valentine’s Day didn’t mean it wasn’t a good time to do some kernel testing, “Because I’m sure your SO [Significant Other] will understand”. The new kernel includes many features. Among them is support for faster system call emulation in Wine, the ability to have unprivileged OverlayFS mounts, and support for Intel’s Software Guard Extensions (SGX). We’ve previously covered the saga that was the implausibly long journey toward the merging of SGX after many dozens of tries. The announcement of Linux 5.11 would ordinarily lead to the immediate opening of the “merge window” for Linux 5.12. The merge window was delayed this time, however, on account…

Q Where is sda? I recently bought an Intel NUC computer running Ubuntu_20.04. The Disks utility, or df -h shows /dev/ nvme0n1p2 as the volume where I expected /dev/hda. Otherwise things are normal. Could you advise me if I need to do anything? Mike Jones A The short answer is that you don’t need to do anything – this is quite normal. In Linux, disk devices are named according to the interface through which they’re connected. In the days of IDE drives this was indeed /dev/hda,b,c. SATA drives used /dev/sda, and in fact IDE drives – if you could find one – now also show up as /dev/sd* because they use the SATA code. However, SATA is, for want of a better phrase, old hat and we have a…

Having reviewed countless phones over the past 15 years, one of the most striking aspects about the Cosmo Communicator is the unboxing. The box lid, adorned with a crisp photo of the Cosmo, flips open, much like the phone itself. This presentation is not only superb, it hints at what is in store for the unsuspecting user. There’s a direct lineage from the must-have 1990s PDA to the Cosmo Communicator, reflected not only in the form factor, but also in the software. You’ve got Agenda for managing your calendar, Data for creating databases, Airmail for email, Notes for notetaking, LEDison for editing the cover LEDs, and even a voice assistant. Each of these tools wields the Planet Computers logo and is a serious attempt at branding. We’d like to see…

Despite being a crucial and inseparable part of the graphical desktop metaphor, window managers don’t receive the same attention as that enjoyed by desktop environments. To be clear, all desktop environments feature a window manager, which among other things, is responsible for the placement and appearance of all the open windows. Different desktop environments make use of different window managers. For instance, KDE has KWin, Gnome 2 uses Metacity, Gnome 3 has Mutter and Xfce has Xfwm, to name but just a few. Even apart from these, there are more than a dozen different window managers for you to use, and you can switch the window manager without changing the desktop environment. In fact, you can also use a window manager without a graphical desktop environment, which is the focus…

You can edit Awesome by making changes to the ~/.config/awesome/rc.lua file but it doesn’t exist by default. You have to first create the ~/.config/awesome directory manually, and then copy the sample rc.lua file from the /etc/xdg/awesome directory. Whether it’s titlebar items such as close or maximize, their position, or the context menu background, everything is controlled by editing the config file. The other window managers are no different and also require manual manipulation of config files. When you first run i3, it offers to create the config file for you by starting the i3-config-wizard. It asks you to specify the modifier you wish to use. The default is the Windows key, but you can choose an alternate such as Alt. IceWM distinguishes itself by enabling you to tweak a vast…

You may wish to have the SSH daemon listen on a port other than the default (22), to avoid the most primitive of port scans. You can do so by editing /etc/ssh/sshd_config and changing the Port directive to something obscure like 2222, restarting SSH and finally making an appropriate firewall rule with $ sudo ufw allow 2222 Likewise, to enable HTTP and HTTPS requests to a web server (so that you could access your Nextcloud instance, for example) you would use the same command with ports 80 and 443. If you were running a LAMP stack, MySQL (or MariaDB) ought to have been configured to listen on the local loopback address. There’s generally no need for it to be accessible to the outside world. Whole books have been written on…

In 2015 I started using Raspberry Pi computers in the classroom. It was my first teaching post. I’d been using them for a while outside of teaching, but I could have never predicted the change bringing in just a few Pis would enable. It was transformational for computing, design technology, science and so much more. I never thought it would change my teaching so much. Within six months we had ordered a class set of Raspberry Pis and I’ve never looked back. When I moved to set up Spark Penketh, the first makerspace in a UK state school, a Raspberry Pi lab was first on my list. It enabled us, with limited funding, to extend our computer labs. We used the space to teach Python, Linux, HTML, Java, JavaScript and…

The Raspberry Pi Pico is impressive in that it provides a highly flexible development environment. For reasons of convenience, the following steps were performed using the stock MicroPython firmware readily available at www.raspberrypi.org/documentation/pico/getting-started. Our program isn’t large enough to warrant the creation of a custom build, which would only slow us down. Actual program development is then done on a workstation running Ubuntu 18.04 and the Thonny IDE. Unfortunately, it can’t be installed from the package repository of the distribution: the Raspberry Pi Pico core expansion works best with at least version 3.3.3+ of the product. Given that MicroPython is an interpreted language, you don’t need to worry about connecting a PicoProbe or similar debugging hardware. The USB interface of the microcontroller is used to host a REPL console –…

FreeDOS is an open source implementation of MS-DOS that works with more modern machines. We installed FreeDOS on an Asus eeePC 701 and it makes a great “retro” machine that boots in less than 10 seconds. FreeDOS was created to enable anyone to run their old DOS games and productivity software on newer hardware. Downloading a USB image from the FreeDOS website (www.freedos.org) and then writing the image to a stick takes no time at all and the installation process on our test machine was quick and painless. If you’d like to run FreeDOS on real 486 hardware then there are many options available, such as a legacy CD-ROM image or a Boot floppy and CD-ROM download that has the necessary CD-ROM driver for MS-DOS. FreeDOS can be used in…

Different colour channels contain varying amounts of digital noise. This will be important if you want to display your black and white photo as a large print, and could influence your choice of how much of each colour channel to use in the mix. Cutting the blue component in a black and white conversion has another effect – reducing atmospheric haze – which can be especially effective in mountain scenes. Increase it and it’ll enhance haze, thereby making misty early morning scenes look more atmospheric. In the film era, monochrome portrait photographers sometimes used green filters over the lens to darken skin tones. When digitally converting a colour photo, you’d achieve much the same effect by cutting the red component.…

CODE EDITOR CudaText Version: 1.123.6 Web: http://uvviewsoft.com/cudatext We surely need “moah” text editors in Linux, don’t we? In fact, whatever title we choose to pick, it’ll normally be unique and carry a custom set of features and plug-ins. Here’s one more such application, this time positioned as a code editor – CudaText. It’s versatile, extensible, and sometimes feels like a small IDE. At first glance CudaText gives us a feeling of déjà vu since the application clearly borrows its visual design from Sublime Text. In fact, the official CudaText Wiki even goes as far as to include a dedicated list of advantages of CudaText over Sublime Text. The list includes cool features such as coloured UI tabs, better performance and the ability to open any file without size limitations. Given…

If you aren’t using Arch Linux and don’t want to reboot your computer to use a live disc, you can do the whole job in a virtual machine, including compiling the kernel, but booting Qemu from an ISO image. Once you’ve done that, much of the process is the same but you’ll have to partition your disk image in the emulator rather than using the whole disk approach, as we’ve taken here. You’ll also need to make sure your emulator has networking already set up because installing Arch from the live disk involves downloading packages. You don’t even have to use Arch Linux, although the installation instructions we’ve given here apply to Arch, and it does have the convenience of being able to install the most minimal, and fast booting,…

You can create a standalone executable version of your space shooter. Run pip3 install pyinstaller to get the dependencies sorted, then pyxelpackager shooter.py to turn shooter. py into an executable. Create your own image sprites in the pyxel engine editor by running pyxeleditor. It’s an intuitive pixel image editor, useful not only for this project, but any retro creation you might be working on. Pyxel github page features a comprehensive wiki guide on how to use the game engine. Try playing around with different image sets and sound effects to altar the game experience: https://github. com/kitao/pyxel…

Another useful tool that can help you create graphs and plots is Graphviz (http://graphviz.org). It’s is a collection of tools for manipulating graph structures and generating graph layouts that supports both directed and undirected graphs. It offers both graphical and command-line tools. Graphviz uses its own language. The good thing is that Graphviz is open source and its language is easy to learn and use. As with Markdown, you can write Graphviz code using a simple plain text editor such as vi. A wonderful side effect of it is that you can easily develop scripts that generate Graphviz code! So, Mermaid and Graphviz have many things in common including using plain text files and producing output in various formats. However, with Mermaid, you don’t need to install anything whereas for…

USING THE LXFDVD Using Linux for the first time can be very confusing. It’ll most likely be unlike anything that you’ve operated before, especially if you’re used to Microsoft Windows or Apple macOS. Generally our DVDs are designed to be run directly, which is to say that when you first power on your PC (or Mac, see below) it should ‘boot’ from the DVD – so before Windows or macOS even starts to load – with Linux running directly from the DVD. This trick is known as a Live Disc. It enables you to try out the various versions of Linux without having to install or change anything on your PC. Just remove the DVD, restart your PC and it’ll be exactly as you left it. While many systems will…

I’d always say the biggest security threat to any system is the human using it. That’s not because said human is malicious or incompetent – people make mistakes, after all. But that’s compounded when you’re effectively tricked into making mistakes by phishing attacks or malware. A lot of phishing is carried out to compromise online accounts and Linux is lucky that most malware still targets Windows. But equally those puny human design systems that are flawed, and not always in obvious ways. Two-factor authentication is an awesome tool and it can make you feel super secure… even when the system is flawed. After all, when you can just select a “forgot your password” link and have everything reset, then any extra security goes out the window. Security isn’t a feature,…

Red Hat’s decision to kill off CentOS is still having repercussions in the industry. Rocky Linux, an alternative to CentOS created by CentOS co-founder Gregory Kurtzer and announced as soon as Red Hat’s plans became known, has just received a major boost, with a new startup company, Ctrl IQ (https://ctrliq.com) announcing that it’ll be sponsoring the distro. Interestingly, Ctrl IQ was founded by Gregory Kurtzer. The company, which will offer a ‘fully supported technology stack’ to help enterprises improve their workflows across multiple sites or cloud services, will use some of its income to help develop Rocky Linux – which is still in very early days. Rocky Linux looks like it’ll form part of Ctrl IQ’s services. However, a Ctrl IQ representative told Ars Technica (http://bit.ly/LXF274ArsCtrlIQ) that Ctrl IQ remains…

DEVUAN GNU+LINUX 3.1.0 This Debian fork, which is designed to give users a version of Debian without relying on systemd, has a new version out that supports three alternative init options: OpenRC, SysV init and runit. You can also install lilo, an alternative bootloader to GRUB. You can also easily exclude non-free firmware as well when installing the operating system. ARM and virtual images haven’t been updated with this release, however. Find out more at http://bit.ly/LXF274Devuan. OPENMANDRIVA LX 4.2 OpenMandriva Lx 4.2 is now out, and is the first release of the project to support the Aarch64 architecture (used by 64-bit ARM processors). This means it can be installed on the likes of the Pinebook Pro and various Raspberry Pis. This new version comes with the latest KDE applications, along…

"We’re coming up on 12 months since the beginning of the pandemic. Many of us are fortunate to be able to work from home, and any attempt to complain about the times we live in needs to be placed in context. We could have it so very much worse. Yet much uncertainty still remains. We don’t know when we’ll be able to get together again, or what that will even look like. Especially in Open Source, occasional gatherings are a key part of our collaborative process. We can manage without, but we’re better for an ability to get to know one another through periodic offline interactions. Yet many companies and people will take things slowly, even after vaccines are widely available, and hesitancy will surround events, due to the risks.…

Linux has two main tools for finding files: locate and find. The former works by keeping a database of files on your system. It’s fast, but limited to files that were present when the database was last updated. Most distros install a cron script to keep the file database up to date. Locate is also limited to searching on file names. To use it, type: Add -i for a case-insensitive search. The alternative is find, which searches the filesystem directly. It’s slower, and can only search areas the user has permission to read, but provides completely up-to-date information. It also enables you to specify which directories to search or exclude, and search on properties other than the file name, such as the file’s owner or creation date. The first line…

A bit slack I’m a frequent reader of your great magazine, although I confess that I read a copy from my local library in the Blue Mountains, Australia. So I’m not contributing much financially I’m afraid. My email is to request or suggest that at some stage you might like to add the wonderful Slackware Live DVD/USB stick/CD either to your DVD or perhaps mention it in an article? The original page is here: https://alien.slackbook.org/blog/ slackware-live-edition. It’s the work of Eric Hameleers, one of the titans of Slackware Linux, and has saved me from some mistakes in my own Slackware setup many times. And with the release of Slackware 15.0 coming up soon, it would be nice if Slackware was given a bit of publicity. Andrew Strong Neil says… I’m…

We assessed the window managers on a dual-core processor machine fitted with 4GB RAM and running Manjaro Linux. Our reason for choosing this particular distribution was the availability of the latest release of the different window managers in its repositories. With the exception of fvwm3, which requires manual installation, all the projects are also available in most popular desktop distributions such as Fedora, Ubuntu and Mageia. The four classes of window managers each comes with its own pros and cons. We’ll rate each one, and test the ease of installation and availability of plugins or extensions that make it possible to change the look and feel of the different window managers. A major advantage of working with window managers is the level of control they provide in shaping your desktop.…

There are dozens of window managers for Linux distros, but not all are available in the software repositories of most distributions, and some haven’t seen a new release in years. Openbox, Fluxbox and JWM are incredibly robust and popular stacking window managers. Our reason for not selecting either was that they haven’t published a stable release in many years. The same is true for ratpoison, a lightweight tiling window manager that’s aimed at power users. dwm is another tiling window manager, but it has the distinction of following a self-imposed guideline of not exceeding more than 2,000 lines of code. If you can stand a desktop that features no window decorations, icons or buttons, try your hands at StumpWM tiling manager. On the other hand, if you fancy eye candy…

The biggest threat to home users is social engineering. A text message might dupe you into visiting a web site that looks exactly like your bank, a cold caller might ask for personal information, or a PDF attached to an innocuous-looking email might cold-heartedly encrypt the contents of your hard drive. Being able to spot these things and exercise caution go a long way. New vulnerabilities are discovered daily, so it’s important to keep systems up to date too, especially internet-facing servers. Many people implicitly rely on their home routers for security, and this is mostly reasonable. But in the age of IPv6 and IoT where everything is addressable and your fridge runs Linux, this is a fragile thing to be relying upon. It might not seem so devastating if…

The Raspberry Pi 4 and 400 both have USB 3.0 ports, which we can use to boot via a USB-to-SATA adaptor. After using the Raspberry Pi SD Card Copier to copy our install to a blank SSD, we can open a terminal and open raspi-config: Navigate to Advanced Options and press Enter. Go to Boot Order and press Enter. Select USB Boot and press Enter. There you go! After a quick reboot to configure the EEPROM of your Raspberry Pi 4, running the latest Raspberry Pi OS will now boot directly from USB. If you forget and leave the microSD card in the slot, fear not. USB is the first boot device, but it’ll fall over and use microSD if no USB device is present. Booting from a USB device,…

Creating a high-accuracy instrument is an interdisciplinary task. One nice area of improvement involves the reference voltage fed into the ADC. The Raspberry Pi Pico board doesn’t enables us to harness the entire capabilities of the RP2040 microcontroller. A detailed explanation of the issues faced can be found in section 4.3 of the Raspberry Pi Pico datasheet document. Should you feel like improving your reference voltage, please avoid falling victim to the accuracy fallacy. The reference voltage doesn’t necessarily need to be precise: in the end, no one cares if the absolute value is 3.205V or 3.235V. Instead, absolute stability is important – keep in mind that components are affected both by ambient temperature and aging. If you have a stable voltage reference at an odd voltage level, values can…

There are many good reasons for keeping multiple copies of files stored securely on different machines: backing content up is the obvious one, but it also offers the ability to quickly share files with others without having to jump through hoops such as uploading to cloud storage or emailing zipped files. The best tools are those that are unobtrusive. You spend a little time setting things up, of course, but once done they can largely be left to their own devices, working seamlessly in the background continually monitoring folders and uploading any changes without disruption to your workflow. The best type of tool for this job is a continuous file synchronisation tool, and our favourite by far is Syncthing (https://syncthing.net). Read on to discover what it does, why you should…

The FT2332H board’s name probably refers to the RS-232 serial interfacing standard. Now largely superseded by USB, it’s still used in some applications, for example if you need to exceed USB’s maximum lead length of 5m. If you have any equipment with an RS-232 interface, the FT232H enables you to interface it to your PC. A solder pump is a useful tool if you’re going to be soldering because the occasional mistake is inevitable. It has a spring-loaded plunger enabling you to suck the solder off a previously made joint after you’ve melted it with your soldering iron. Don’t be tempted to try and interface an FT232H or an MCP2221 to mains-powered equipment via electronic components on a breadboard. It’s possible to control mains-powered gear, but for safety reasons this…

When developing and testing software, it helps to have a stable base platform on which to test it. This is particularly true when doing anything low level that would otherwise involve rebooting to test. For this type of testing environment a virtual machine is often the best option. It boots quickly, it doesn’t interfere with your normal system and if it goes wrong, you can easily delete it and start over. In this article we’ll see how you can create a virtual machine image based on Arch Linux, a distro popular among those who like to get involved with the nuts and bolts of Linux (but may not have the patience to install Gentoo). One of the useful side effects of the way in which Arch Linux (and Gentoo) are…

X programs such as xterm and xclock don’t exactly tax the graphics system. If you run software that’s more demanding, you’ll see that running X on Qemu like this leaves you with graphics that are a little, well, pedestrian. This is a combination of the use of the VESA driver for the virtual graphics card and the total lack of any acceleration. You can use the -vga option to use a faster virtual graphics card, you’ll then need a driver for it in your guest system. Another alternative is to use SPICE (www.spice-space.org). This is a remote display protocol that’s used to communicate between the guest and host, to display the guest’s desktop in a window on the host. There are a number of resources to help you with this,…

Typora is a stable and easy-to-use Markdown editor and reader that also supports Mermaid and works on many operating systems including Linux. On an Arch Linux machine you can install typora by running sudo pacman -S typora . Adjust the command to match your Linux variant to install typora on your own Linux machine. The biggest advantage of typora is that it’s an editor. You can see the real output as you write it without needing to take any extra steps unlike Microsoft Visual Code. Additionally, you get to see syntactic errors in your Mermaid code as soon as possible and you can export your files in various formats including PDF, LaTeX and HTML. However, you can’t run typora from the command line because it’s a graphical application, which means…

"2021 is off to an exciting start in the land of VR on Linux. Monado, the OpenXR runtime for Linux, is now an officially conformant OpenXR implementation! The Khronos listing of conformant OpenXR 1.0 implementations, which previously included Facebook, HTC, and Microsoft, now also includes Monado, a free, open source runtime that’s passed the OpenXR conformance test suite on a simulated device. Collabora doesn’t produce any hardware, therefore anyone building a product using Monado with non-simulated hardware still needs to go through the full, normal adopter and conformance process for that product to claim OpenXR conformance and take advantage of the benefits. But that’s another story for another time. In recognition of this milestone, we’ve also made our first proper release version, moving away from the 0.X.Y version series to…

Developers of Skroutz, an eCommerce platform used in Greece, found a ‘fairly old’ bug in the Linux kernel. In a blog post (see http://bit.ly/LXF274kernelbug),Apollon Oikonomopoulos explained that “every now and then, an rsync transfer from a source server would hang indefinitely for no apparent reason… What’s more, for reasons that became apparent later, the issue could not be reproduced at will, although some actions (e.g. adding an rsync-level rate limit) seemed to make the issue less frequent.” The team contacted Linux networking maintainers, and less than two hours later a patch had been developed (see http://bit.ly/LXF274kernelpatch). It’s alarming to know that this bug has been around for 24 years. However, by finding and fixing the bug, the Skroutz developers were “rewarded with a nice adventure, where you get to learn…

"In January Elastic announced a software licencing change. This means that search project Elasticsearch and data visualisation tool Kibana would no longer be available under Apache 2.0 and instead will be under Elastic’s own license and MongoDB’s Server Side Public License. Elastic says it’s unfair for cloud companies like AWS to provide a cloud service based on Elasticsearch for profit, but not contribute back. The result is that Elastic has made its open source project proprietary. Also, while the target is AWS, other service providers and companies may also be affected. So, how does this impact the wider world of open source? First, companies may have to think more carefully about the open source licence approach they want to adopt, to ensure no nasty surprises in future. Second, this can…

Linux uses some complex data structures to track its internal state. Much time and effort has been spent optimising the choice of algorithms and the structures in memory that they operate upon. Yet there’s always room for improvement, particularly when it comes to contended structures that don’t scale well in today’s multi-core world. Readers may be familiar with popular data structures such as a hash, dict or a map. These are containers used to store data in a way that’s more efficient to index or search than just a simple list. In the latter case, a naive algorithm may have to iterate through every piece of data to find the one of interest, while structures enable data to be organised in a way more conducive to fast lookups. Trees may…

We’d love to try and answer any questions you send to lxf.answers@futurenet.com, no matter what the level. We’ve all been stuck before, so don’t be shy. However, we’re only human (although many suspect Jonni is a robot), so it’s important that you include as much information as you can. If something works on one distro but not another, then tell us. If you get an error message, please tell us the exact message and precisely what you did to invoke it. If you have, or suspect, a hardware problem, let us know about the hardware. Consider installing hardinfo or lshw. These programs list the hardware on your machine, so send us their output. If you’re unwilling, or unable, to install these, run the following commands in a root terminal and…

Awesome closed its community-run wiki a few years ago. If you wish to engage with the user community, you can post questions to Stack Overflow, or use the /r/ awesomewm Subreddit. The project’s website also hosts a Recipes section which is home to several useful snippets and tutorials to get the most out of awesome. Despite having been around for over two decades, there’s no official documentation on Enlightenment. The project also doesn’t host an official forum board or mailing list for users to interact with one another. Your only options are to either use the #e IRC channel to engage with user and developer community or rely on third-party forum boards such as LinuxQuestions.org. The IceWM website is home to plenty of documentation and also hosts man pages that…

As humanity becomes ever more connected, so our lives and information about them move ineluctably online. In times past, the only information about citizens was held in paper records in churches or council chambers, and consisted of little more than names, occupations and dates of birth. A few conquests and burned libraries later this information moved to mainframes in government buildings, regular folks started having bank accounts and companies began to store and share customer data among themselves (and advertising agencies). You might even have found yourself in a phone directory or found your beloved in a lonely hearts column. Fast forward to today and an average human generates gigabytes of information a day (and counting), which companies, authorities and criminals would love to get their hands on. Some of…

Public Key Cryptography always seems a little like magic when you first hear about it, and this article is unlikely to demystify it any, but one (ahem) key point is that public keys should be as public and widely known as possible. We’re not jeopardising Mint’s security by printing their public key here because knowing that won’t help anyone deduce any information about their private key. If anything, we’re helping them by making it more available (albeit in frustratingly hard-to-transcribe paper form). If an adversary tricks you into thinking a public key under their control belongs to someone else (or you blindly trust a key from a forum post), then they can use it to imitate that person. All signatures will check out fine and you might end up divulging…

Controversy over Pi OS Microsoft repro The community pushes back over official support for Microsoft’s Visual Studio Code repro in the Pi OS. On 25 January Raspberry Pi OS received an update that was neither posted to the GitHub repository, had an announcement or discussed beforehand (http://bit.ly/lxf274naughty). The update added a repository and GPG key for a developer called… Microsoft. Cue outrage. The official response was that the change was made to facilitate the easy installation of Visual Studio Code by beginners, as VS Code is one of the official IDEs for the new Raspberry Pi Pico. There was also a “This makes it easier for people who use VSCode so it will be staying” response, which anyone will know won’t bring a happy end to discussions. The official Raspberry…

To use an FT232H or MCP2221, you have to solder the header strips on to them, but if you’ve never used a soldering iron, you might be wary of trying. That’s understandable because if you make a mistake you could trash the board. Soldering isn’t difficult, but you should read some tutorials first and practise before attempting to solder something that matters. We suggest you get hold of some stripboard, otherwise known as Veroboard. This is an insulating board that’s drilled on a 0.1-inch grid, and with copper strips on the back. It works much like a breadboard except that instead of just pushing leads into the holes, you pass them through the holes and then solder them on to a copper strip. It provides a means of prototyping that’s…

Les Pounder is associate editor at Tom’s Hardware and when not writing about Raspberry Pi he is found tinkering with old computers. MS-DOS is not case sensitive, unlike Linux. So QBASIC and qbasic are one and the same. DOSBox has a basic form of history, which we can scroll through using the up and down arrows. We can take Windows 3.1 for a spin in our browser. ClassicReload has a web-based version of DOSBox, which means we can skip creating a virtual machine and start enjoying this classic interface: https:// classicreload. com/win3 xwindows-31.html Windows 3.1 just a little too retro for you? You can take Windows 95 for a spin in your browser.See www.pcjs. org/blog/2015/09/21. Windows 95 had a massive marketing campaign, and saw users queuing overnight to get their hands on an…

They might not be black and white, but sepia photographs are certainly monochrome. We’re all familiar with these historic-looking photos, but we might not be aware why they have their characteristic colour. It’s not a result of the passage of time on photos that were once black and white, but as a result of chemical additions that were used to make early photos less prone to fading. The fact that it gave them a quite pleasing warmish tone was just a lucky accident. Here’s how you can generate them from colour originals. GIMP has a Sepia tool (click Colors>Desaturate>Sepia). You can use it on a colour image but it doesn’t offer a lot of control. It enables you to specify the Effect Strength – and reducing it results in a…

Don’t start the emulator while the image file is still mounted on the host. Giving two operating systems access to the same filesystem is asking for trouble. Enable CONFIG_ IKCONFIG and CONFIG_ IKCONFIG_PROC in your kernel config. This makes the kernel configuration available in the file /proc/ config.gz, so you can easily check if a required option is set from within the guest that’s using grep. Always keep a back-up image that you never use directly. Breakage is an inevitable consequence of experimentation, so be ready for it. The cp command should recognise the sparse files and then copy them quickly.…

Space Invaders is probably the most famous space shooter of all time, released way back in 1978 for arcades. Originally called Uchu Shinryaku-sha in Japan, Space Invaders was the first fixed shooter, and paved the way for shooting games as a new genre. The idea being that the player controlled a space ship at the bottom of the screen, and it was their job to move left and right to avoid enemies, while shooting rockets up the screen to destroy them. Nice and simple fun, so let’s have a go at creating our own take on this retro classic. We’ll be using Python to code our game, since it’s one of the most versatile, accessible high-level programming languages on the market. Python is completely free and should be installed on…

If Mermaid isn’t to your liking, try Vega and Vega Lite, which enable you to create graphs and plots. Both grammars are based on D3.js and JavaScript. Learn more about Vega and Vega Lite at https://vega.github.io/ and at https:// github.com/vega/vega. If you want to create advanced and exceptional output, then have a look at D3.js (see LXF265 and LXF220), which is a powerful low-level JavaScript library. The official web site for Mermaid is at https:// mermaid-js. github.io/ mermaid. The GitHub repository for the Microsoft Visual Studio Mermaid extension is at https:// github.com/vstirbu/vscodemermaid-preview. Learn more about the Markdown language at https:// en.wikipedia. org/wiki/ Markdown.…

FRESH AND FLAVOURSOME MIN SPECS: 64-BIT CPU, 1GB RAM, 15GB DISK SPACE, SVGA DISPLAY Mint 20.1 “Ulyssa” There’s nothing quite like a new edition of Linux Mint to complement the coming of spring (or autumn for our topsy-turvy southern hemisphere readers). We’ve been recommending it to beginners for many years. The distribution is entirely funded by donations and sponsorship, and has a large and friendly community who will be only too happy to help you if you get stuck. Mint is based on Ubuntu (probably the world’s most popular desktop Linux distribution), and uses Canonical’s repositories so users have instant access to the wealth of thoroughly tested software there. They also enjoy the same generous five-year support period of the Ubuntu LTS, so you can happily keep using this release…

Blender magic Now used in top-flight games, box office releases, prime-time TV and more, we welcome you to the dazzling world of Blender. Chat with Jitsi We show you how to create a basic chat server so you can message, call and video chat – all in complete privacy. Code education Dive into the world of educational programming – we explore the many options teachers, parents and students can use. Digital audio workstations The Linux world has pro-level audio solutions and we look at the best low-latency digital-audio software available. Contents of future issues subject to change – we may have eaten all the raspberry pies by mistake.…