Linux FormatFebruary 2021的目錄

Jonni Bidwell According to my inbox, late last night I ordered a significant quantity of Raspberry Pi gubbins. I’ve gotten a soil moisture meter, a temperature and humidity sensor, a mini TFT display and a Pi Zero. So the year will definitely start with some botanically themed adventures, and my houseplants (what sort?–Ed) will grow yet mightier. Nick Peers 2021 is the year of the self-built Ubuntu 20.04 server, built on a low-powered Celeron J5040 motherboard housed in a four-bay NAS-sized chassis. Migrating everything across from my QNAP TS-251+ is going to be an interesting experience... Les Pounder In 2021 I’m looking forward to RISC-V, open source CPUs, making their mark. Right now I have a RISC-V devboard and a soldering iron on the way. Did you know that RISC-V…

“Since our previous Panfrost update, the open source stack for Arm’s Mali Midgard and Bifrost GPUs, we’ve focused on taking our driver from its reverse-engineered origins on Midgard to a mature stack. We’ve overhauled both the Gallium driver and the backend Bifrost compiler. As a result, Mesa 20.3 now features Bifrost support out-of-the-box. For those of you with GPUs like Mali T860, Panfrost’s support for Midgard has improved as well. Over the summer we added support for Arm FrameBuffer Compression (AFBC) as optimisation for certain workloads. Recent builds of Mesa will automatically compress framebuffer objects to save memory bandwidth, improve performance, and reduce power. Panfrost is smart enough to compress textures as AFBC on the fly, improving texturing performance for applications that don’t support compressed texture formats like ASTC directly.…

Linus Torvalds announced the release of Linux 5.10, noting that things had calmed down and “nothing makes me go, ‘We need another week.’ Things look fairly normal.” With the release of 5.10 comes the “merge window” (period of time during which disruptive changes are accepted) for that will be 5.11. This usually runs for several weeks at the beginning of a cycle, but Linus noted that the timing of the 5.10 release around the holidays meant that he would be especially strict about only accepting patches that were ready to merge. Among many other new features, 5.10 includes support for AMD SEV (Secure Encrypted Virtualization), memory hints targeting other processes, and fixes to improve the performance of indirect branch Spectre mitigation. This kernel has been blessed as the next “Long…

Q Minty screen trouble One fine morning I turned on my laptop, fully expecting my trusty Linux Mint 19 Tara to emerge triumphantly on screen, and for brief moments everything looked normal but, alas, no desktop or beautiful GUI ever appeared! The Mint logo appears with the five dots as if loading the system, remains stuck there for more than a minute and a half, then goes into a loop: 1) Screen goes black for 50 seconds 2) Arrow cursor appears for 30 seconds 3) Screen goes black briefly 4) Horizontal blinking underscore appears top left on screen for about 30 seconds 5) Screen goes black for 50 seconds, and the loop starts again This seems to go on indefinitely. I have tried updating the system, but there seems…

We’re in the era of some of the best space-based storytelling thanks to series such as Star Trek: Discovery, The Mandalorian, The Expanse and many more. Whether it’s because of these, or because you’re naturally curious about and fascinated by the vastness of space, and its constituents such as galaxies, solar systems, planets and more, your Linux distribution can help fuel your passion with many different applications aimed to help you stargaze. The nature of the Roundup format is such that there can be only one winner. For specialised tools such as the ones featured here, this is an especially difficult task. We’ve tested the different applications on a range of subjects, but they’re easy enough to get your hands on, so you should give each of them a fair…

As with all niche software, their popularity doesn’t always result in the latest version being made available in the software repositories of most popular desktop distros. With the exception of SkyCharts, all the other applications are available in the software repositories of distributions such as Ubuntu, Fedora, openSUSE, Debian, Arch and others. The project provides 32- and 64-bit packages for Windows and Linux, providing both RPM and DEB packages. You’ll also find the DEB package for RPi ARM as well as FreeBSD. Similar packages are available for different catalogues. The documentation provides up-to-date instructions on how to install the project on different platforms, and even distros such as Mageia, Debian, Ubuntu and more. You’ll also find instructions on creating a portable instance of SkyCharts, which can be run from a…

There are other RAID levels, too. A RAID6 configuration might have four drives that use maths to spread parity data such that any two drives may expire. When a drive fails it should be replaced immediately. You can mount an array in degraded mode (so long as too many drives haven’t failed), but you won’t have any redundancy until the array is reconstructed. So cautious data fiends will keep spare ‘hot’ drives enrolled in their arrays that can be summoned into service. Rebuilding can take a lot of time (potentially days when terabytes of data are involved) and deeper RAID levels involves a lot of disk hammering, so there’s potential for cascading failures. Many motherboards have their own, proprietary RAID implementations (pejoratively termed FakeRAID), and hardware RAID controllers are still…

Assembling your own robot and getting it to walk around will entertain kids of all ages for a good few minutes. However, for robotics to be long-term fun it needs to be a challenge. A common misconception about robotics is that you need a degree to make anything of your own. Having said that, a robot does require many subsystems to operate. There are legs to move, arms to stretch, things to see and react to. Basically, everything we do as humans – except you must design the entire system that can handle all those tasks. This isn’t something you whip up in your man cave on a rainy afternoon. Being free and open source enthusiasts, we know better than to believe we have to cover every detail ourselves. There…

If you want to use JavaScript and interface directly with Arduino and other system-on-chip boards, consider these simpler systems. They’re designed to interface directly to a large amount of boards, including the Arduino, Raspberry Pi and other small boards. Johnny-Five is one popular such framework, which interfaces to these boards using JavaScript. The team behind it, Bocoup, has partnered with SparkFun to create a kit that you can start playing with on delivery. At the website (www.johnny-five.io) is a long list of examples that demonstrate how you can control and read a long list of servos and sensors. Cylon is another solution – it’s a single NPM module. If you already have some JavaScript projects going, this takes minutes to set up and get started with. It was built using…

You can only use uppercase letters to define ‘handles’ in pdftk. You can, however, use a single letter or use them in combination to define ‘handles’. For instance, you can use A, B, D, Z, TT or ASD as your ‘handles’. The man pages, help command and the website for projects like Ghostscript and pdftk are all excellent resources to help you master their myriad capabilities. You’ll find various tutorials and instructions online, and even on YouTube that describe how to perform the different operations. The ocrmypdf utility exits with an error if the specified PDF file has already been OCR’d. You can use either the --redo-ocr or the --forceocr command options in these cases.…

Want to convert Blu-rays? You’ll need MakeMKV – follow the installation guide at https://bit.ly/ lxf272makemkv then use it to convert your discs to MPEG-2 MKVs, which you can import into Handbrake. If you’re ripping directly to MP4, prevent Handbrake from saving your file in the M4V format by selecting File> Preferences> General tab and unticking ‘Use iPod/iTunes friendly (.m4v) file extension for MP4’ before clicking OK. Want to rip DVDs using Handbrake? Issue the following commands: $ sudo apt install libdvdpkg and $ sudo dpkgreconfigure libdvd-pkg…

Photo stacking often requires changes to be made between taking individual shots. As an alternative to a fully automatic mode, many cameras now offer this degree of manual control, even though many people haven’t used it. Achieving a correct exposure involves balancing the camera’s speed (often referred to as the ISO setting), the shutter speed and the aperture – the degree to which the iris shutter is open and hence the effective diameter of the lens. For best results you need to use a fairly low ISO setting, say 100, because a high speed requires the camera to amplify the signal more and this generates noise. So we’re left with shutter speed and aperture. Decreasing the shutter speed – say from 1/250 to 1/125 seconds – increases the amount of…

HyperCard has a text-based language – HyperTalk. Click Objects>Button Info>Scripts to edit the HyperTalk code to quickly add features. The syntax is easy to read and is more akin to reading instructions than code. Creating a virtual HDD in BasiliskII can save your work and speed up the emulation process. Multiple hard drives can be used to emulate different systems, including early OS X machines. If you enjoyed HyperCard and want to use it for a project then there’s a modern version for Python. It’s called PyperCard, and this module provides a HyperCard experience and enables rapid prototyping of GUI applications in Python. See https:// pypercard. readthedocs.io/en/latest.…

In the main part of this tutorial, we customised an image by working in a Docker container. However, another way of doing things is to create an image manually from what is called a Dockerfile. Below is a simple example Dockerfile: Create a fresh directory and put the content above into a file called Dockerfile. Create a file called hello.txt and put some text into it. The three lines of this simple Dockerfile tell the build process to use the debian:latest image as the base image, copy a file called hello.txt into a directory called /myfiles/ after having created that directory, and finally, run the commands apt update and apt install nano . From the command line on your host, run docker build -t example:nano . . The dot at…

A CPU has a limited number of registers. For Linux, C/C++ and assembly language programs to play together nicely, you need to know which registers you can change and which you must preserve. You need to know which registers will be changed by the functions you call and which will be preserved. You need to know which registers will be used to pass arguments into your functions and in what order. Your assembly language programs will only work if you obey the same rules that the Linux kernel and C obey. The eight argument passing registers, in order, are X0 through X7. So the first argument is always passed in X0 and the eight (if there is one) is passed in X7. Any additional arguments must be passed on the…

Some of the retro video games we’ve created in this series have been public domain and/or without any image sprites. This game, however, requires bitmap graphics, and with Angry Birds being one of the more recent releases, it’s very much under copyright protection. We’ve made sure to use royalty-free sprite images. It’s important to bear in mind that while this code is a free and open-source recreation of the original Angry Birds game, if we were to use the original images, or code, for that matter, we’d be infringing Rovio’s copyright. Open Game Art is a fantastic resource for finding FOSS graphics for video games. The graphics we used in this project were created by www.kenney.nl. Their collection consists of over 50 material elements in three different variants, which comes…

2021 is the year everyone can blast off with Linux! There’s the aging meme – it’s the year of the Linux desktop! – that’s supposedly a call to arms for mainstream consumer Linux adoption. The irony, of course, is that it hasn’t happened, even though Linux is now running pretty much everything else in the world: from your Android phone and tablets, to the fastest supercomputers and large chunks of the internet. The last holdout is the consumer desktop. There are very good reasons why Linux hasn’t had a look-in here. The Microsoft Windows monopoly ensures consumers only ever get to see Windows pre-installed on systems they buy and, of course, there’s human laziness to factor in. You might not like it but Windows works well, and has all the…

An increasing number of Linux distributions are dropping their 32-bit editions and moving to only supporting 64-bit kit. As a result, a huge amount of 32-bit systems may be in danger of being abandoned. Many 32-bit machines are embedded systems, as well as some Android tablets running on ARMv7 processors, and while 64-bit replacements have generally been brought in, there remains a sizable amount of 32-bit machines out in the world. The problem is that while the manufacturers of these systems are promising continued support, the reality is more complicated. As LWN.net explains (https://lwn.net/Articles/838807), while the OpenRISC project is still active, many of its contributors have moved over to working on RISC-V. Other 32-bit architectures, meanwhile, are just being left to die. Further complicating things is the fact that many…

RESCUEZILLA 2.1 This user-friendly disk imaging software has been updated with a much-requested new feature that enables you to easily mount and open Clonezilla images and access files, along with some important bug fixes and performance improvements as well. Two versions are available – one based on Ubuntu 20.04, the other based on Ubuntu 20.10 – and you can find out more at https://bit.ly/LXF272Rescuezilla. T2 SDE 20.10 A new stable release of this ROCK Linux fork has been released, which makes it possible to build your own Linux distro. This latest version has been a long time coming – after a decade of development! It’s a huge update with over 1,000 new packages, and includes the latest Linux kernel, together with updates to Firefox, KDE, GNOME and lots more. Check…

“ There are many things about 2020 that will go down in the history books. Activities that we used to take for granted were upended in an instant. There was much sadness, yet also optimism about what can happen when we come together, and about how we can adapt to a new normal and persevere. In the year ahead, there’s much that we still don’t know. But we do hope that at least some of the things we used to do will return once more. And there are some things that won’t change. There’ll still be Linux kernel releases, and we’ll still write about them. Over the course of 2021, we can expect five or so kernel releases, taking us up to 5.15 (or even 6.0?). Of the many features…

Computers are supposed to make life easier for us, so performing tasks on time without us needing to intervene seems like a good idea. The program used to do this is called cron. It loads a set of cron tasks that are run at the times specified, all without any need for you to lift a finger, or even remember. There are three ways to set up a cron job. As a user, you run $ crontab -e to edit your crontab file. For system jobs, you can edit /etc/crontab, but this isn’t advised as this file is usually managed by your package manager. The usual way to run system tasks is to either drop a script into /etc/cron. {hourly,daily,weekly,monthly} or add a cron task to a file in /etc/cron.d.…

You’ll find these applications in the software repositories of most desktop distributions, even if the featured version is not the latest. Some programs provide Snap packages, and others provide installable binaries for RPM- and DEB-based distributions. We’ll test the programs on the ease of availability and support for different platforms and devices. We’re running these applications on a quad-core machine with 12GB RAM, without a dedicated graphics card, even though some of the tools suggest the use of one for optimum performance. With expansive projects such as these, users will find themselves at sea in the absence of thorough documentation. We’ll rate the projects also on the feature set, and whether or not you can search for objects and look up co-ordinates in the sky. We’re looking for tools that…

Virtual Moon Atlas is designed to observe the Moon. You can similarly use PreviSat to track satellites, and observe their orbits. If you’re particularly interested in the surface of planets, try your hands at Virtual Planet Atlas, while the Digital Universe Atlas presents a 4D visualisation of the sky. You can access the digital universe using two open source applications. OpenSpace, which is partly funded by NASA and Partview, by the National Center for Supercomputing Applications. If you’re interested in a little out-of-the-box experience, try the Mars Simulation project. It’s aimed at building computer models that simulate different aspects of establishing a human colony on the red planet. Finally, why not try the Fedora Astronomy release, which features many applications aimed at astronomy buffs and astrophysicists? There’s also Astronomy Linux…

YARP is the framework for communications within robotics. It can replace the ROS master as a name server. You can also do this the other way around using the YARP as a name server. The name server will support the nodes and protocols across your system. You can also use both in a single system. One reason why you may want to use this is if you have a single unit that requires a separate underlying protocol. Another reason might be because your project is in transition between the two frameworks. These protocols can be used in other fields. For example, if you have a number of Kubernets nodes you can have them share information using either YARP or ROS. The project is fully open sourced and available on https://github.com/robotology/yarp/releases/latest.…

Elementary OS lands on the Raspberry Pi The world is getting armed and dangerous, as another distro joins the Raspberry Pi army. We get the feeling that people like the Raspberry Pi, because the latest distribution to offer direct support for the tiny computer is Elementary OS, as revealed in a blog post back in December 2020. After all the work it had put into making Elementary OS available for the Arm-based Pinebook Pro it’s decided it wouldn’t be such a leap as to offer experimental builds for the Arm-based Raspberry Pi 4 boards. The dev team is pretty open about performance levels, what you can expect and what doesn’t work. It recommends a Pi 4 with a minimum 4GB of memory, but ideally the 8GB model. It also recommends…

Certbot is a tool from the Electronic Frontier Foundation that automates the generating and updating of free SSL certificates from Let’s Encrypt. This enables you to serve content over HTTPS, which provides encryption, but also some guarantees that you’re in charge of your machine. Anyone can generate a certificate for any domain (you can make one for google.com if you want), but in order for it to be trusted by browsers (and display a friendly padlock) it must be signed by a trusted certificate authority. Let’s Encrypt will do that signing for you, if you pass its verification. Install Certbot and the Apache plugin (which will save you editing any files), and then enable the SSL module: $ sudo apt install python-certbot-apache $ a2enmod ssl Add the following directive (changing…

While we’ve discussed a number of different utilities to manipulate PDF files in different ways, your Linux distribution has still more tools to offer, for still more operations. The poppler-utils package is a collection of tools built on Poppler’s library API. Each of these tools is designed to work with PDF files and even extract content from them. You can install the popplerutils package by running the sudo apt install poppler-utils command if you’re on a Debian, Ubuntu or derivative distribution. Run the sudo dnf install poppler-utils command if you’re on a RPM-based distro such as Fedora. The package includes many different utilities such as pdftohtml that can be used to convert a PDF file into HTML while retaining the formatting of the original PDF file. The command pdftohtml filename.pdf…

Looking to convert videos into a universal format guaranteed to play on just about any device? Then you need a video converter capable of encoding your video in the universal H.264 or H.265 codec, wrapped up in a MP4 file container. You could use the codec’s own command-line tool, but that becomes unwieldy when you realise just how much fine-tuning’s required to compress your video to a small enough file without making it unwatchable. What you need is a point-and-click solution in the form of Handbrake (https://handbrake.fr). The program gives you full control over your video conversions via a more user-friendly graphical front end. However, its vast array of options and tabs can make it confusing for beginners. Never fear: read on for our exhaustive step-by-step guide to the whole…

For years H.264 has existed as the closest thing to a ‘universal’ codec, supported by just about every playback device: computer, mobile and smart box. It’s getting a bit long in the tooth as resolutions continue to scale up, which is why H.265 was developed. H.265 produces better-quality video at higher compression levels, resulting in smaller file sizes This makes it a better choice for hi-def videos of 2K (1080p+) resolution and up. Those advantages stretch to both SD and HD files too, so with this in mind, choosing H.265 seems like a no-brainer, right? Not necessarily. First, H.264 is more widely supported, so if you’re after a truly universal video file that’ll fit virtually any playback device, it’s still the number one choice. That said, H.265 is gaining in…

We’ve focused on manual processing in GIMP because it shows better what’s happening, but many of these techniques can be automated. An obvious contender for automation is aligning mismatched images and here an automated solution will offer results as good or better than the manual method. A well-respected solution is the align_image_stack command line instruction that’s part of Hugin. This describes itself as a panorama photo stitcher, but it also offers a large selection of image-processing tools. Next up is averaging photos, which is a time-consuming process using the manual method if you’re working with lots of images. Unlike other photo-stacking techniques, the process is a straightforward mathematical process and so the results are likely to be just as good as with manual processing. There are lots of packages here,…

If the thought of running an emulator leaves you cold, we can emulate a classic Mac from a browser. Courtesy of https://jamesfriend.com.au/pce-js we can emulate a Macintosh Plus running 7.01 and even play a few games. This emulation is powered by JavaScript and it’s a version of Basilisk II in the browser. This is an extremely easy way to sample the Macintosh Plus. The emulator is powerful enough to play games from the mid-90s and we thoroughly tested the emulator by playing the original Star Wars vector game. Created by James Friend, this web-based emulator is awesome and the source code can be found at https://github.com/jsdf/macemu. James has provided quick links to a pre-configured Macintosh Plus running System 6 and featuring classic applications and games of the era, including Aldus…

Go to https://hub.docker.com, click Explore and check out the fascinating array of pre-made images. The Hub is organised into categories, so you should be able to find anything that you’re looking for, or perhaps, you’ll come up with some crafty ideas you’d never considered before? By default, a command like docker pull debian pulls through the latest version of the image, but we could have specified, for example, debian:unstable to pull that version instead. Browse https:// hub.docker.com/ to see what versions of an image are available. You can often run GUI applications in a container thanks to the networking facilities of X11, the most common Linux windowing system. prince0203/ x11-firefox is an image on Docker Hub that gives you a containerised version of Firefox that you can deploy with a single…

What if you want to take a customised image and transfer it to another computer for use, without using the cloud? It’s a pretty simple process. First we need to create a single tar.gz image containing the image. Start by typing docker save -o ./[filename].tar. gz [name or ID of image] to bundle up our image into a file in the current directory. You can then move this file (using networking or a flash drive, for example) to another physical machine and load it into your Docker setup there. To do this, load the file using docker load -i [filename of .tar.gz file] in the same directory as the file. It’s now installed as an image, and you can verify this by typing docker images. Create and run a container…

FERAL FELINES MIN SPECS: 2GHZ CPU >> 4GB RAM >> 25GB DISK Ubuntu 20.04.1 Yes, we know, Ubuntu 20.10 is out (and it won’t be that long until 21.04 is released, but remember we write from long in the past Covid-covered mid-December). Still, if you’re looking for a swift, stable OS that you can keep relying on till 2025, then this is it. With this August point release the usual huge package upgrade post-install will be a little less huge. If you have the bandwidth though, do check for a second point release. Also on the cards will be the HWE (hardware enablement) packages, which will suit people with modern hardware. Hybrid graphics (the scourge of laptop users) should work much better with this release. If you have such hardware…

THE LXF LIBRARY Advanced Bash Scripting Guide Go further with shell scripting. Bash Guide for Beginners Get to grips with the basics of Bash scripting. Bourne Shell Scripting First steps in shell scripting. The Cathedral and the Bazaar Eric S Raymond’s classic text explains the advantages of open development. The Debian Book Essential guide for sysadmins. Dive Into Python Everything you need to know. Introduction to Linux A handy guide full of pointers for new Linux users. Linux Dictionary The A-Z of everything to do with Linux. Linux Kernel in a Nutshell An introduction to the kernel written by master hacker Greg Kroah-Hartman. The Linux System Administrator’s Guide Take control of your system. Tools Summary Overview of GNU tools. GNU Emacs Manual Six hundred pages of essential information! Producing Open…

Many CentOS users have been left fuming after Red Hat, the distro’s parent company, announced that it’ll be ending support for CentOS 8 by the end of 2021 – a good eight years earlier than initially promised. In a blog post (which can be read at https://bit.ly/LXF272CentOS), the company stated that “the future of the CentOS Project is CentOS Stream,” and that once support for CentOS ends in December 2021, CentOS Stream will serve as the “upstream (development) branch of Red Hat Enterprise Linux.” It means that CentOS will no longer be a rebuild of Red Hat Enterprise Linux (RHEL), which for many people was a key selling point. Instead, it’ll be a rolling release Linux distro, similar to Arch. Rather than having fixed releases where major updates are released…

“So Red Hat has pulled long-term support on CentOS and some of the Open Source community are up in arms about it. They’re wrong to be. CentOS was always the “free” version of Red Hat. Functionally identical, but with the branding removed. A lot of people used CentOS because they wanted Red Hat but didn’t want to pay for Red Hat support. Red Hat is a commercial company and it’s in business to make money. It’s never pretended otherwise. Despite that, the company has made enormous contributions to Linux that we all benefit from. Furthermore, when Red Hat acquired CentOS almost seven years ago, it continued to make the Linux distro available without charge. The community owes the company a huge debt of gratitude. Instead, many are badmouthing Red Hat,…

“ The recent proliferation of multiple ‘Source Available’ and ‘open source-compatible’ licenses for previously open source databases has led to some hefty problems. If you don’t spend time researching and understanding the fine print of these licenses, then you can end up with all the features of a project that you want, along with a new one: lock-in. One of the strengths of open source is the relatively small number of licences. GPL, BSD, MIT and Apache are well understood and account for over 90 per cent of released software. At Percona, we’ve been discussing how ‘Not Open Source, Source Available’ licensing could be more widely understood. One example is the Polyform project. This is a group of licensing lawyers and technologists that have developed a set of standardised licenses…

Maxim Levitsky (Red Hat) posted a patch titled “RFC: Precise TSC migration” that led to discussions on how KVM (the Kernel Virtual Machine hypervisor built into Linux) should handle Time Stamp Counter (TSC) synchronisation between guest and host, and between guest and host on the new host during a live migration. Thomas Gleixner (Linutronix, others) posted further patches aimed at getting some of the core RT (Real Time, aka preempt-rt) code into the upstream kernel. Real Time support has been available since the mid-2000s but never in a Linux kernel, although recent efforts are close to changing that. To make it happen, such things as core softirq needs to be fully preemptable, which was posted in “softirq: Make it RT aware”, among other pieces. Chris Browy (Avery Design) replied to…

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…

If you were wondering, the GNU Hurd is the GNU project’s replacement for the Unix kernel as opposed to an OS using the Linux kernel, the BSD kernel or historically the AT&T System V kernel. It’s a collection of services that run on the Mach microkernel to implement file systems, network protocols, file access control and other features that are implemented by the Unix kernel in a POSIX-compatible way. The aim of GNU Hurd is to create a general-purpose kernel suitable for the GNU operating system, which is viable for everyday use, and gives users and programs as much control over their computing environment as possible. So far the main way of running a live GNU Hurd system was with Debian Hurd (www.debian.org/ports/hurd),but now Guix Hurd can be added to…

Thanks to films, pop culture references in comic books, songs and TV shows, we all know that early civilisations identified celestial objects with gods and spirits. Stellarium ships with four different sets of sky cultures: Western, Chinese, Ancient Egyptian and Polynesian. Stellarium and KStars both have an astronomical calculator; however, the implementation is different for both. This is an advanced featured that might not appeal to novice users, but can be used to compute the movement of different objects such as stars, or even planets, over time. The two applications also do a stellar job of simulating different eye pieces and telescopes, essentially showing you how a particular area of space would look when seen through the selected device. Instead of manually selecting the different bodies or objects that hold…

New year, new Linux. That’s what you promised yourself, right? Maybe not, but it’s what you and your hardware deserve. It’s never been easier to get started with Linux, and Ubuntu, one of the world’s most popular distros, has never been in better shape. If you don’t believe us, try it out risk free from our DVD. Once you’re convinced, and ready to give your previous operating systems the boot (ill-fitting pun intended), we’ll show you how to install it, use it and get the most out of it. And if you read the above paragraph, smug and aloof that you’ve already got your favourite distro installed, but slightly concerned this feature won’t help your new year, fret not. We’ve got some great tips for tweaking and perfecting your install.…

My name is Andrew and I’m an electronics/computing hobbyist and former teacher of computing who has a passion for Raspberry Pi and micro:bit. Like many Raspberry Pi users who grew up in the 80s, for me the Pi captures some of that excitement of the early home computers which felt very ‘open’ compared to modern computing devices. Using PEEK and POKE statements to read and write the I/O registers on my Commodore 64 gave me an insight into how computers work that isn’t so readily available when staring at a GUI. Following the PCB tracks to work out the circuit diagram for my Jupiter Ace gave me a clue as to how computers were built. I feel the Pi brings some of that exploration back to computing. The Raspberry Pi’s…

Manjaro Arm runs well on the Raspberry Pi 4 thanks to its 1.5GHz quad-core CPU. But if we want to squeeze out a few extra MHz, then we can overclock our Pi by editing a single file. You’ll need to cool your Pi 4 – consider a Pimoroni FanShim, which is cheap and effective. Inside the boot partition is a file called config.txt. From within Manjaro we can edit the file via the Terminal: $ sudo nano /boot/config.txt Using the arrow keys, move to the bottom of the file and add the following lines to both increase the CPU speed to 2.1GHz and overclock the GPU. #Overclock arm_freq=2100 gpu_freq=750 over_voltage=6 Press Ctrl+X, then press Y and Enter to save the file. Reboot Manjaro and enjoy the speed boost! To check…

The official Nextcloud mobile app is available from the Apple App Store and Google Play. But if you have an Android device then you really should source it from F-Droid (and be running a de-googled version of Android). There’s also a desktop Linux version that will be in your distros repos (it’s available as a Snap and AppImage, too). Just like Dropbox (only better), it’ll keep the folders of your choosing synced. Once you’ve got that set up, you’ve got a fully functioning location to store files and share photos. Nextcloud has its own internal utilities that do an awful lot more, and some of those have companion mobile applications, too. You’ll find the Apps screen from the menu in the top right when you’re logged with the administrator account.…

According to the statistics released by Adobe as part of the 25th anniversary of PDF in 2018, more than 200 billion PDF files were accessed using Adobe products in 2017. In the years since, and taking into account non-Adobe products, the sheer number of PDF files accessed in a year, or even on a daily basis is practically incalculable. The trusted and popular document format started its journey as a proprietary format at Adobe in 1993, and was released as an open standard in 2008. Today, there are a large number of graphical and command-line utilities that you can use to not only read, but also manipulate PDF files. Here, we’ll discuss everything from splitting large PDF files into smaller ones, or merging multiple small files into a single PDF…

Averaging is often used in astronomical photography. Shooting astronomical objects usually requires long exposures and this will cause noise to build up. With several shots, the object will always be in the same place but the noise will differ. Averaging will reduce noise. For stacking applications that don’t involve settings to be altered between shots, you might be able to use an intervalometer, aka interval timer, to take the photos automatically at a specified interval. Some cameras have this built in or, alternatively, for cameras with Wi-Fi or Bluetooth, a phone app could be used. Apps can also do interval timing on a phone’s camera. Instead of having to take lots of photos, very long exposures can be achieved using neutral density filters. These reduce the amount of light entering…

WEB BROWSER Waterfox Version: g3.0.0 Web: www.waterfox.net Time for a privacy talk. As long as we spend lots of time browsing the web, then that’s largely a web browser talk. Anyone running Linux knows there’s a wide variety of browsers for any taste, but opening the hood reveals a much narrower choice: either the Chromium engine or the much weaker WebKit engine. Thankfully there is a third way: Firefox is a high-quality mainstream browser. Mozilla says it cares about privacy, but there are also third parties developed forks of Firefox with enhanced privacy settings. One of the best of these forks is Waterfox, which all Firefox lovers should definitely give a try. The main difference between the original and its scion is that the latter strips off telemetry, doesn’t ‘phone…

If you don’t already have a 64-bit OS on your Pi then follow the following procedure to install 64-bit Ubuntu. Go to www.raspberrypi.org/downloads and install the appropriate version of the Raspberry Pi Imager on your desktop computer and install Ubuntu 64-bit Desktop. You don’t need a desktop OS if you just want to edit, compile and run assembly language programs, but if you just have the server OS, you’ll have to use scp to copy the files on to the server. Connect the Pi to your router with an Ethernet cable if you’re using the server OS. The desktop OS will enable you to select your wireless IP address as part of initialisation and select a user name and a computer name. For the server OS you must first login…

Try creating more content for the level. Adjust the x- and y-coordinates in the following code, where x=1000 and y=130 and each box is 100x100 in size: box = make_sprite(43, “images/ boxCrate_ double. png”,(1000, 130),self.space) We’re using some pretty basic graphics. You could try replacing our images with original content of your own. We recommend GIMP for image manipulation. Why not take the game to the next level? When the bird defeats the pig, load up a new scenario with a different layout and an increased number of pigs and obstacles.…

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…

Open source game engines Gaming is big business and occasionally fun too. Discover how you can get started with the best game engines around. Do the Samba It’s back-to-basics time as we cover network shares using Samba and Active Directory domain control. Interrogate satellites Look at them up there, orbiting around us like the Sun shines out their antennas. Let’s find out what they’re transmitting. Switch to the ZFS With zetabytes of storage you need the right file system to help you out, but is the ZFS right for you? We have all the answers… Contents of future issues subject to change, much like our waist measurements after Christmas dinner.…