Linux FormatMay 2019的目錄

Jonni Bidwell More and more I find myself focusing on the not-so-smart things, so this is a really tricky question. I dunno though, Vernier calipers are pretty smart. Oh, and the people that do the Royal Institution lectures. Christian Crawley Sorting out the kids’ dance lessons, telling me where I need to be (and where to go) while working to resolve the concerns of residents as a local Councillor, the smartest thing in my life is without doubt my wife, Ceri. John Knight I don’t have any ‘smart’ gadgets at home, but I have ideas for an off-grid cabin powered by renewables. A collection of Raspberry Pis would be excellent for regulating power and lighting, and their low-power consumption would be perfect for computer usage without draining watts. Les Pounder…

Application services company F5 Networks has acquired Nginx for the princely sum of $670 million. Gus Robertson, CEO of Nginx, commented that “F5 shares our mission, vision, and values… they bring to bear a tremendous amount of additional resources and complementary technologies”, and assured Nginx customers that “F5 is committed to keeping the NGINX brand and open source technology alive. Without this commitment, the deal wouldn’t have happened for either side.” You can read his full statement at http://bit.ly/LXFNginxBlog. Any fears that F5 Network’s purchase will simply assimilate Nginx seem to be unfounded, with the Nginx brand remaining a separate entity. Robertson will join F5’s senior management team and continue to lead Nginx alongside Igor Sysoev and Maxim Konovalov, Nginx’s founders, while Nginx’s operations will continue at its existing offices…

“The standard IT support model of yesteryear was ‘wait until it breaks’. Support departments were event-driven, where an event was a user calling them to report a problem. Today, we should distinguish between user support – helping someone to use IT effectively – and system support, where we keep things running. The events that drive system support should come from a monitoring system, not the users. Why? There are three reasons. Firstly, waiting for systems to break implies an impact to the business before you fix anything. That’s not acceptable. Secondly, your users won’t tell you that the MySQL replication is five hours behind the master, or that the second disk in a RAID set has failed. You’ll only find out when more things break, and you’ll almost certainly have…

The EU Radio Equipment Directive (which can be read at http://bit.ly/ LXFEURadio) has an inclusion that has worried many people, at this early stage. It requires manufacturers of routers, and other devices sending and receiving radio signals, to place a block on allowing customers to install software that has not be certified by the original manufacturer. This effectively means any third-party developed router firmware such as the Linux-based OpenWrt (https://openwrt.org), which offers additional features and greater control, could no longer be installed. Worryingly, this won’t just be limited to preventing custom OS installations on routers, but potentially any other devices such as GPS, smartphones and more. The FSFE published a Joint Statement against Radio Lockdown which has been signed by many organisations and businesses concerned about this. You can read…

“I’ve lately been playing a lot with different computer architectures that interest me. An architecture describes the kind of fundamental instructions that are understood by a family of computers; for example ‘x86’ for Intel and AMD, ‘arm’ and ‘riscv’. For example, nearly everyone reading this has an x86 laptop computer, and maybe an Arm-based Raspberry Pi or three for various projects. But for other kinds of computer, it’s much harder to get one at home. In some cases, this is due to cost. Few people have the space, power budget or building structural support, let alone the money, for a personal mainframe. In other cases, scarcity is a factor. Older computers are hard to come by, some are so new that they haven’t been made yet. The latter case includes…

Chances are that you discovered Linux many years ago and since that day you have enjoyed the fruits of what was initially a laboured introduction. Moving from Windows to Linux introduces a new way of thinking and working – software from a central repository versus a random EXE download being the first hurdle. But what if you’re new to Linux? Well, on Linux Presentation Day you can meet like-minded individuals (how do you know what I’m thinking?–Ed) who want to help everyone to enjoy using Linux. Originally begun in Germany in 2015, Linux Presentation Day takes place twice per year in locations across Europe. The events are free of charge and are a way to introduce Linux to the public via installfests, lessons and social events. The main goal of…

Q Document scanning workflow After using Linux for technical work and development for a while, I’d like to completely move all office-related tasks to Linux (Manjaro KDE) as well. Besides some minor issues with printers, the main impediment is how to set up my document scanning workflow. Currently I scan all incoming documents in one go, manually ‘staple’ them into individual multipage PDF documents and store them to Evernote. Could you recommend document scanner hardware and corresponding software to manage the workflow and store the documents? Roland Stadler A As far as hardware is concerned, any scanner with an automatic document feeder (ADF) that is supported by Linux should do the job. Check the list of supported hardware at http:// sane-project.org and pick a device that suits your needs and…

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…

Managing a network of computers is an involved process. The constant barrage of repetitive tasks such as running checks, troubleshooting errors, replacing dead hard disks and doing fresh installations over and over again can sap the energy out of any system admin, irrespective of the size of your realm. Even before you can tackle the problem of actively monitoring the machines, you have to install an operating system on each of them. This is a time-consuming task even for a small network with, say, 10 computers. Computer cloning involves setting up the operating system, drivers, software and data on one computer, and then automatically replicating the same setup on other computers. The technique, also known as ghosting or imaging, is used by system admins for rolling out multiple identical machines…

Voice recognition is reasonably taxing CPU-wise, so you’ll need at least a Pi 2 to run Picroft. Even that will struggle and the official word (see https://mycroft.ai/documentation/picroft) is to use a Pi 3. That way you also won’t have to worry about getting Wi-Fi working. Since the Pi’s onboard audio doesn’t have any kind of analogue input, you’ll need a USB microphone. We hit up our friends at ModMyPi and got the reasonably fancy Seeed ReSpeaker mic-array, which has four microphones so can determine the direction of an audio source. You’ll also need some kind of speaker; this could connect either to the 3.5mm analogue output or via USB, or via HDMI if your display has speakers. Bluetooth audio may work, but users (that’ll be me–Ed) have reported problems with…

We’ve barely scratched the surface of what openHAB is capable of, but it’s just one of a number of platforms that can interoperate to one degree or another among themselves and indeed Mycroft. For example, there’s a Minecraft plug-in for openHAB, so you can control actual devices in your house from the voxellated world of the game. It uses the popular SpigotMC plug-in – look it up. You can also use openHAB to communicate with Nest devices and Amazon Echo. We could actually write a whole feature spanning the diverse selection of robots and circuits it’s capable of interfacing with (well, if you’re offering… – Ed). There’s also a Mycroft skill for controlling devices connected via the popular open source Home Assistant platform (www. home-assistant.io), which can talk to all…

It’s hard to overestimate all the fine-tuning that goes into Ubuntu, Manjaro or any other desktop-centric distribution. Recreating some of those tweaks in Arch is tricky, but some of them are small things that make surprisingly big differences. For example, your command line life will be markedly improved if you install the bash-completion package, which provides tab completion for most commands. Note that you get filename completion in Bash as standard – this package intelligently completes command options, which is tremendously useful if you’re delving into unfamiliar systemd or Qemu incantations. In our Arch-based distos roundup in LXF246, we found some great features in Antergos, ArchLabs, KaOS, Netrunner Rolling and Manjaro. Some of these would be hard to recreate from scratch, like ArchLabs’ stylish Openbox/Polybar/tint2 combo. But some are easy.…

Shadows can ruin even the best stop-motion animations, yet this problem can be easily avoided with a bit of forward planning. Lighting is the secret, but you need to avoid relying on daylight or a standard ceiling light. This needn’t cause you to break the bank, either; small LED lights perfect for this can be bought for just a few pounds. Positioning the lights to the left and right of the animation ‘stage’ enables you to cancel out any shadows cast by you or the camera. If you’re animating with objects, toys or modelling clay, a third light from above will also help to cancel out shadows. With the shadows banished, you should also ensure the white balance is set correctly. If you’re using the recommended PiCamera software, auto white…

You would think that the knowledge that a straight-through connection, or a null modem connection, is required for a bit of kit to work would be provided in the documentation. It’s my experience that this knowledge, more often that not, is lacking, however. With the demise of COM ports as computer hardware, a lot of knowledge about serial communications has been misplaced. The belief now seems to be “Just hook it up and it’ll work!” We need to restore the lost knowledge to troubleshoot connection issues. One caveat to keep in mind is not to apply both connection methods at the same time. If the manufacture has switched the pins and a null modem cable is installed, two rights in this case make a wrong. Think about it: pins 2…

Digital photography has been become both a blessing and a curse. It’s almost inconceivable to remember the time when every photo was precious, eagerly awaited with a mixture of anticipation and dread. Nowadays, digital clutters up your hard drive with dozens – if not hundreds – of photos for every major life event, never mind the rest. Thankfully, there’s a tool that can help bring order to your chaotic collection. Shotwell doesn’t simply bring your photos into a single library: you can use it to organise them a myriad of different ways, from date-based events to keyword tags. It even offers a selection of handy image-editing tools to help lift lacklustre photos through creative use of colour and light correction, cropping, straightening and even removal of the dreaded red-eye. Shotwell…

You can also import directly from your camera – Shotwell uses gPhoto 2, which supports most models (visit http://bit.ly/ lxf249gphoto for a list of over 2,500 models). Connect your camera to your PC with a USB cable, then with Shotwell open, switch the camera on. After a short pause you should see your camera’s pictures fill the Shotwell window – look in the left-hand menu where you should see a new Cameras submenu with a ‘Mass Storage Camera’ entry indicating it has been recognised. Tick the ‘Hide photos already imported’ to prevent accidentally importing the same photo twice in future, then either click ‘Import All’ to bring them all across to your photo library, or Ctrl-click those photos you wish to import before clicking ‘Import Selected’. Wait while Shotwell imports…

Because Audacity cuts out the complex audio buses that underlie big editing suites, adding effects is incredibly easy. Just select whatever audio you want to apply an effect to and choose it from the Effect menu – and if more input is required, most effects have a settings window with a handy Preview button. As for the effects included by default, you will want to pay particular attention to Fade In and Fade Out, Amplify, and Equalisation. Note that Amplify is useful for making things both louder and quieter, as you can simply enter a negative value if you want to turn something down. While Audacity has a number of effects pre-installed, we recommend installing extra plug-ins. Audacity supports LADSPA, LV2, Nyquist, VAMP and VST plug-ins, and you should be…

It’s not the most riveting topic, but there is an important need to perform a good backup. Critically, make sure you have a backup of the source VirtualBox machine. Losing this would be catastrophic because there is no way to put the HTML output back into WordPress – or at least, not without a lot of manual effort. Luckily, backing up the VirtualBox server is as simple as ensuring the virtual machine is shut down and then copying the folder and its contents to a backup location, ideally an external drive or such. Restoring the VM is as simple as copying it back to your local system and then importing it into VirtualBox, from the menu. Backing up the HTML code is important, as mentioned, for version control. Assuming you’re…

If you’re dedicating a Raspberry Pi entirely to running Steam Link, and you’re mostly aiming for sofa gaming, it might make sense to remove the need to manually launch the program when the Pi powers on; that way, you can do away with the mouse and keyboard entirely. Raspbian Stretch has a number of methods to run apps automatically, but editing /etc/rc.local is the simplest way to do it. Open up a terminal and run sudo nano /etc/rc.local to begin tweaking, then make a new line just above exit 0 . Add the text sudo -u pi /usr/bin/steamlink & . The ampersand is important, because without it, the Pi’s boot process won’t properly complete. Then save the file by hitting Ctrl+X followed by Y. Reboot your Pi and it should…

Git is a version control software system that keeps track of all of the changes you’ve made to your source code and enables you to revert to a previous version at any time. It’s important to keep Git up to date by checking in (committing) your source code frequently – whenever you have made changes that you’ve tested and are happy with. This is particularly important in continuous integration/ deployment environments. This git-checking script stemmed from a current C++ project has seven different source directories, with a single Git repository that spans all the directories. To put these projects under Git source control, we’d open a terminal in the project’s base directory, ~/Development/UDS (the ultimate parent of all of the source directories) and issue the Git init command. This makes…

The Cargo tool is very powerful and can help you develop Rust applications. Let’s look at most popular and useful commands of this tool, along with a small explanation in order to help you remember them while learning Cargo. The cargo new command creates a new project – by default, that project will lead to a binary executable. Should you wish to create a library, you should execute cargo new --lib instead. cargo build compiles a debug version of the local package along with its dependencies. On the other hand, cargo build --release generates an optimised binary executable or library. The cargo clean command removes artefacts that Cargo has generated in the past – it will enable you to build a project from scratch. The cargo run command runs the…

USING THE LXFDVD Using Linux for the first time can be very confusing. It’ll be unlike anything that you’ve likely 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) 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 boot from a…

Sat up here in our ivory Linux Format Tower, it’s easy to pour scorn on those lesser non-Linux-using types, hopelessly switching their lights on and off with their phones, asking little round speakers what the weather is like outside their windows and checking if their milk has gone off by looking at their smart-fridge display. But why shouldn’t someone be able to remote-control their lights, control their heating or ask a system what the weather is in complete digital safety? We’re exploring how open source can solve the IoT problem by combining the Mycroft and OpenHAB projects to create a smart, secure voice-controlled open source home. Heck, it even ties into Google Home and Alexa, if that’s your thing. But digital Luddites of the world fret not, if having a…

Purism, the team building the much-anticipated Librem 5 open-hardware smartphone, has announced that its open-source operating system PureOS will be a ‘convergent operating system’ that can run on both the smartphone and laptops. A few years ago, convergent operating systems like these seemed to be all the rage. While some software makers have dropped their convergence plans – most noticeably Canonical ditching its plans for a single version of Ubuntu to run on PCs, phones and tablets, back in 2017 – Microsoft, Apple and Google are all continuing to look at ways to have one OS on many devices. According to Jeremiah Foster, Director of PureOS, Purism has beaten its big competitors to the punch. In his blog post at http://bit.ly/LXFPureOSConv, he says PureOS’s “future applications [will] run on both…

Firefox has announced that one of its most popular Test Pilot experiments, Firefox Send, is getting an official launch. Firefox Send (https://send.firefox. com) enables people to quickly and easily send files with end-to-end encryption. You can drag and drop files onto the web page and a link is created that automatically expires, so nothing is kept online permanently. The service is free to use, and if you sign in you can send files up to 2.5GB in size. It has an impressive list of features, enabling you to specify when the link to the file expires, how many downloads of the files are allowed, and whether or not to add an additional password for extra security. The people to whom you send the link simply need to click it to…

SWAY 1.0 The first stable release of Sway, a “consistent, flexible, and powerful desktop environment for Linux and FreeBSD” as creator Drew DeVault calls it, has been released. In a refreshingly honest release announcement (http://bit.ly/LXFSway1), DeVault explains how “nearly 300 people worked together, writing over 9,000 commits and almost 100,000 lines of code” for this release, which has been completely overhauled for a much better experience compared to Sway 0.15, which was, by DeVault’s admission, a “buggy, frustrating desktop to use.” Download it from: http://bit.ly/LXFSway1Download. REACTOS 0.4.11 A new version of the open source operating system that enables you to run Windows applications has been released. As the release statement notes (http://bit. ly/LXFReactOS), this new version brings substantial improvements to the kernel that improves performance and addresses a number of…

Linus Torvalds announced Linux 5.0, and with it the opening of the merge window (period of time during which disruptive changes are allowed ahead of 5.1). In his announcement, he detailed a few last-minute fixes, and that he was happy overall with having extended the 5.0 cycle by a week, following the atypical 5.0-RC8. The new kernel includes many new features, among them the Energy Aware Scheduler covered in last issue. “PHYSICAL MEMORY QUICKLY BEGINS TO FRAGMENT AS IT IS ALLOCATED AND FREED” It also gains support in the AMD GPU drivers for FreeSync, a technology popular with gamers that smooths the display by aligning the transition of the frame displayed with the vertical blanking interval of the display. A complete summary of what’s new in 5.0 is provided (as…

MANCHESTER MAKEFEST 2019 Taking place on Saturday 25 and Sunday 26 May at Manchester’s Science and Industry Museum, this two-day event celebrates the various groups and skills in the maker community. From Arduino to artisan crafts, this weekend is packed with lots to see and do. You can take the family for a fun day out and learn a new skill. We’ve been to previous years and this is a great venue. so spend the day there! Tickets and details can be found via: www.scienceandindustrymuseum. org.uk/take-part-makefest-2019. MIXIT Taking place on 23-24 May in the French city of Lyon, this event is truly a mix. There are talks and workshops covering Ethics, Makers, Design and Lifestyle from the world of technology. The whole ethos of the event is to “discover new…

Send your thoughts to the Linux Format dungeon server at linuxformat@futurenet.com, be picked as Letter Of The Month and win* a 32GB Nitrokey Storage 2! The Nitrokey is worth a cool €149, has 32GB of hardware-encrypted storage, supports hidden volumes, secures your online accounts with onetime passwords, can encrypt emails, files and hard drives and is an open source, open hardware solution. Protected with AES-256 and RSA keys up to 4,096! Learn more at www.nitrokey.com.…

Q Do you know if there is a Linux driver for my Minolta QMS PagePro 1200W laser printer? Anna Brand A As with most things printer-driver-related on Linux, the answer can be found on openprinting.org, specifically www.openprinting.org/driver/ min12xxw. This is a third-party driver for your printer, so don’t expect support from the manufacturer. On the plus side, this driver has been around for a good number of years and has been reported to work well. Download the relevant file for your operating system: 32-bit or 64-bit according to your processor, DEB or RPM according to the package manager used by your operating system. If you aren’t sure of the package format, Debian and its derivatives, such as Ubuntu, Mint, Peppermint and others use DEB. Fedora, openSUSE and Manjaro are among…

A disk cloning tool requires quite a bit of hardware to be tested effectively, particularly hard disks. This is why virtual hardware is ideal for testing their capabilities. For this Roundup we’re using several virtual machines with multiple hard disks of various sizes. We’ll use them to image a small disk to a large one, which is one of the most popular uses of a disk cloning tool. Secondly, we’ll clone a large disk with lots of empty space to a smaller one with enough room to accommodate the used sectors of the larger disk. The Clonezilla, G4L and FOG Project tools have been tested on Manjaro, Fedora and Ubuntu installations. WereSync was installed on Manjaro and Deepin Clone was tested atop a Deepin 15.9 installation for best results. The…

Yep, we’re pretty cynical about voice assistants here at LXF Towers. Our (nameless) sister magazines rant and rave about the latest Alexa additions and how they make ordering tat from Amazon even easier. They quietly forgive the chaos that ensues when Siri’s name is spoken on the television, as all the fruity phones within earshot frantically start offering to help. Tech pundits wax lyrical on the importance of shoving a network stack deep into every single appliance in your house so that it can be ‘smart’, so that the ‘smart’ appliances can all chatter among themselves about their dumb masters. If you’re in the isolated enclave known as the UK, your utility providers would dearly love you to have smart meters installed. They tell you this will help monitor your…

Each issue we write a new Raspberry Pi project and each issue we try to be inventive and unique. But there are times when inspiration is not with us, and in those moments we turn to searching Google with key phrases or words, and often they are quite ridiculous. These ‘mashups’ are there to fire the imagination; just as a child given construction blocks can make anything they dream of, we can use these silly searches to think up new and unique ideas. In reality this project is really just three for loops and two lists that store and iterate over user input while it searches Google. Then it opens a random page in our web browser. Let’s get mashing! Before we can write any Python code we first need…

Finding something to animate in your stop-motion movie project might seem tough, but really you can use anything. It could be household objects, or it might be toys. Check toy shops for Plasticine character kits or Lego packs specifically designed for stop-motion projects. It’s almost always more convenient to use a Raspberry Pi without the display. However, for a camera project like this it’s wise to have a monitor connected. Using the preview feature will ensure the shot is lined up and in focus. What type of display you use is up to you, although the larger, the better.…

What sets FFF apart from other file managers is its non-conventional user interface… and its name, of course. It’s not every day one comes across a tool with an expletive for a name, which we won’t repeat here for obvious reasons. You will have to point your browser to the project’s home page at https://github.com/dylanaraps/fff for that. FFF doesn’t exactly have an interface to speak of. Instead it provides a directory or file list, and lets you perform various file operations such as copy, paste, cut and so on. As a shell script, the project also doesn’t have large dependencies, and you can set it up on any Linux distribution – and even BSD and macOS – without any hassles. For all of its file operations, the tool relies on…

If files in the Shotwell library are moved, deleted, or – with removable media – disconnected, they become ‘missing’ and disappear from the main view. You can check these under Library > Missing Files. Either restore the file(s) manually, or select them all and click ‘Remove from Library’ to delete them. Not all date-and timestamps on photos are correct – for example, if you scan in old family history photos. Edit these by selecting the photo and choosing Photos > Adjust Date and Time. Tick ‘Modify original files’ to amend the actual file datestamp. Want to back up your Shotwell library? Because thumbnails are generated automatically, all you need to do is back up the database file – you’ll find this hidden away under ~/.local/share/ shotwell. Visit the FAQ at…

Shotwell’s capabilities can be increased through the use of plug-ins, some of which are provided with the program. These are managed via the Edit > Preferences > Plugins tab, and you’ll see there are three categories: Data Imports, Publishing and Slideshow Transitions. These are the only plug-ins currently published and available for Shotwell, and they do change over time – for example, an option to publish to Facebook was recently removed as it no longer works. You can see the current status of Shotwell’s plugins by taking a trip to http://bit.ly/lxf249shotplugs, where you’ll discover that the obsolete Picasa Web Albums plug-in is in the process of being updated to support publishing to Google Photos instead. If you fancy writing your own plugin, visit http://bit.ly/ lxf29shotplugs2 for a complete guide to…

Running Audacity with JACK rather defeats the purpose of its simple interface, but maybe there’s some kind of effect chain you want to create, or some kind of MIDI program you need to use, and the only way to do it is JACK. First, you need to make sure JACK runs properly. We recommend installing QjackCtl, which provides a straightforward GUI for starting and configuring JACK. If you try to start JACK and get an error, first try specifying your soundcard by clicking Setup, and in the Settings tab will be the Interface drop-down menu. Change the setting from ‘(default)’ to your soundcard’s actual device name. If this doesn’t work, make sure Driver is set to ‘alsa’ instead of ‘dummy’, and if it still doesn’t work, try disabling ‘Realtime’. To…

Most technically savvy readers will know that HTTPS is the way forward, but historically it has always been tricky to configure. Enter, stage left, EFF’s Certbot. This is designed to implement HTTPS easily, and really is super simple. To implement it, do the following: The above provides the dependencies, but to actually run and implement the configuration use the following command: It will take a few moments to run but will configure everything for you. Once it’s complete, assuming that you’ve followed the main guide it should be as simple as reloading the page, simply swapping HTTP for HTTPS. Do note, however, that Certbot only approves certificates for a period of three months. This isn’t too much of an issue because it gives you the option to log in periodically…

Dimensioning shows the sizes of objects as they appear on the page – so nothing larger than 210mm horizontally on an A4 page. This isn’t very useful if you’re designing a kitchen, so use the scale options to adjust this. LibreOffice Draw offers options for editing bitmaps. As you’d expect, you can adjust brightness and contrast, and this basic functionality is enhanced with control over the three primary colours and gamma. Use the Gluepoints feature to add extra attachment points to objects.…

IMAGE ORGANISER DigiKam Version: 6.0 Web: www.digikam.org One of the reasons why digiKam evolves so rapidly is its constant participation in Google Summer of Code, which is hard to underestimate. We’ve extolled the enormous power of digiKam in the past, and it’s only getting better. Its key feature is the ability to mark images with tags and create sorted catalogues of photos. Tagging is incredibly useful; it lets you navigate huge image libraries to quickly find the desired files. digiKam is also very capable at importing photos from various sources. The import window has dozens of options, but perhaps the key one is automatic creation of albums based on dates. This way you can turn a single folder with thousands of files into a much more appealing set of subdirectories…

JavaScript has been the dominant programming language among web developers for a long time now. WebAssembly wants to become the new king of web development – not as a programming language, but as a virtual and portable compilation target. Therefore WebAssembly is not here to replace JavaScript entirely, but to work with JavaScript. The two biggest advantages of WebAssembly are portability and good performance. This tutorial is about writing Rust code, compiling it into WebAssembly and using that WebAssembly code. At the time of writing, the latest Rust version is 1.32.0. However, you should not have any problems executing the code of this article even with older Rust versions. At the end of the tutorial we’ll see how to create WebAssembly code from Go, so we can compare the Rust…

WebAssembly (aka Wasm) is a machine-model and executable format targeted for a virtual machine, designed for efficiency – both in speed and file size. That means that you can use a WebAssembly binary on any platform you want without a single change. It also means that WebAssembly binaries tend to be quite large in size, though this shouldn’t be a problem with modern computers. WebAssembly comes in two formats: a plain-text format and a binary format. Plain-text format WebAssembly files have the WAT extension, whereas binary files have the WASM file extension. A WAT file uses S-expressions, whereas the binary format can be executed by Wasm virtual machines. An S-expression is an older textual format used for representing trees. In the case of WebAssembly, an S-expression is used for describing…

READING MATTER 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 Source…

“Just a few weeks ago at the Game Developers Conference (GDC) in San Francisco, the Khronos Group released the OpenXR provisional specification. And that same day, Collabora announced Monado, a free and open source XR platform, and first OpenXR runtime for Linux. OpenXR is an open standard that aims to unify and simplify the creation of experiences in augmented reality (AR) and virtual reality (VR), collectively known as mixed reality (XR). Monado enables applications and game developers to target GNU/ Linux without having to worry about hardware enablement. Monado also helps the hardware developers add support for their devices on GNU/Linux. My hope is that Monado becomes an ecosystem composed of key XR industry players and enthusiasts in the open source community. Going forward, my goal is to create a…

Microsoft has been making some welcome and well-received overtures to the open source community lately, but when announcing the latest version of Skype for Web, among a number of new features Microsoft let slip that its browser-based version of Skype will no longer officially support ChromeOS or Linux. Users of those operating systems who try to use the new Skype for Web will now be faced with an error message saying that their device is not supported–though some users are reporting success with Chrome browser or changing the user agent to Windows on ChromeOS. Thus if you’re a Skype user on Linux or ChromeOS, you’ll need to use the native app instead.…

“So GNOME 3.32 came out, and to celebrate I finally switched over to Wayland. Of course, it wasn’t all smooth sailing. As is well documented, I am fond of Guake, the drop down terminal. Unfortunately Wayland has no truck with programs that want to grab keystrokes without focus, so its handy F12 hotkey didn’t work. Since I spend most of my time writing in LibreOffice (we both know that’s not true – Ed), pressing this key resulted in the current paragraph becoming the first item in a list. Frustrating, but of course this is expected behaviour; it’s just that under X, that F12 keystroke could be intercepted to prevent this unwanted listifying. The future of tech journalism may well sadly be listicles, SEO-friendly headlines and simplification beyond recognition. But such…

David Howells posted a Request For Comment patch series titled “Containers and using authenticated filesystems”, intended to start a conversation about containerising the kernel’s support for crypto keys that it can manage on behalf of filesystems and other subsystems. The patches introduced a new, explicit notion of a container in kernelspace, which has not previously been the case. These ideas were rejected for a variety of reasons, but they may just start a new dialogue about in-kernel container representation. Sasha Levin proposed a discussion at the upcoming Linux Storage Filesystem and Memory Management Summit about the preferred tests that should be run against patches destined for -stable kernels. Stable kernels are those released by Greg Kroah-Hartman and based upon existing Linus kernels with various fixes and backports, intended for those…

Build Brighton Thursday evening is open night. www.buildbrighton.com Cornwall Tech Jam Second Saturday of the month, alternating between Bodmin and Camborne. www.cornwalltechjam.uk Glasgow Makers and Hardware Hackers Mitchell Library, Glasgow. https://m.facebook.com/groups/115303729096198 Huddersfield Raspberry Jam Meet every month at Huddersfield Library, typically on the fourth Saturday of each month. https://huddersfieldraspberryjam.co.uk Horsham Raspberry Jam Parkside, Chart Way, Horsham. www.facebook.com/hackhorsham Leeds Hackspace Open night every Tuesday 7pm-late, open day second Saturday of the month, 11am-4pm. www.leedshackspace.org.uk Medway Makers 12 Dunlin Drive, St Mary’s Island, Chatham ME2 3JE. www.medwaymakers.com New Jersey Linux User’s Group Last Tuesday of every month, at Panara Bread, 165 Route 4 West, Paramus, NJ. http://njlnux.org PLUG – Perth Linux Users’ Group Once a month, at Spacecubed, 45 Saint Georges Terrace, Perth, Western Australia. www.plug.org.au rLab Reading Hackspace Unit C1, Weldale ST,…

Getting RC with the Pi My ongoing project is to take old RC cars and replace the receiver/controller IC with a Raspberry Pi. I have tried a number of different solutions such as WebIOPi and Wyliodrin, but Les Pounder’s article on Flask in LXF229 gave me another solution that I have got working and which I really like. Another aspect is to untether the car from the access point, and I wonder if Les could do an article on setting up a peer-to-peer ad-hoc network between an android tablet and a Raspberry Pi? [Peter found a solution at http://bit.ly/LXF249point. For the benefit of other people who don’t like doing things the easy way, I have discovered that each of the three scrap RC cars have a different receiver/control IC, but…

Linux is usually stable enough to survive misbehaving software, but it is possible for a program to lock up the whole computer. Before you reach for the power or reset button and risk corrupting your filesystems, there is a better way to get out of it. You can send commands directly to the kernel by holding down the Alt and SysReq (aka PrtScr) keys and pressing certain letter keys. As the kernel listens for these directly, they work even if X is completely locked and accepting no input. The keys normally used to get out of a lockup are R, to reset the keyboard – this occasionally fixes the problem on its own. Next press E to send a TERM signal to all processes, asking them to shut down cleanly,…

Two of the tools featured in LXF in the past, but not included this time around due to them not showing any signs of life, are Redo Backup & Recovery and Mondo Rescue. The former is by far the easiest bare-metal cloning option we’ve run into. Its downside, however, is that it takes away a lot of the control over the cloning process in lieu of convenience. The only real alternatives for cloning disks besides the ones we’ve already covered in the Roundup are the command-line ones that do the grunt work in the background. The two that are really worth mentioning are Partclone and FSarchiver. They both support a large number of filesystem formats and can quickly roll disks and partitions into movable archives. The real CLI veterans, however,…

The Mycroft Mark 1 launched in 2016 and was powered by a Pi 2, but things have moved on and it now ships with a Pi 3 at its heart. It’s a stylish device, and with its friendly ET-style face you could almost forgive it for listening in to all your living room conversations. Actually, non-creepiness is part of Mycroft’s design – any feature you find invasive or unnecessary can be disabled thanks to its open source nature. Mozilla’s Privacy Not Included site has a favourable write-up at http://bit.ly/lxf249mycroft1 . The Mark 1 device is still available for $180 (we couldn’t find a source for it in the UK, unfortunately), but it was always designed with hackers and hobbyists in mind. A successor is on the way, and the Mark…

The Seeed ReSpeaker 4-Mic Array Pi HAT is, as they say in the business, a nifty bit of kit. As well as four microphones, it has twelve LEDs which can be used to indicate audio direction of arrival, or just to flash randomly and concerningly. It has GPIO and I2C connections so that other devices can be daisychained to it, or it can stack directly onto Seeed’s GrovePi hub, allowing even more sensors to be connected. It uses the AC108 codec which at present isn’t supported by the Raspbian kernel, so we’ll need to install a custom one. Connect to the Pi, either by SSH or keyboard, and quit the Mycroft CLI. Run the following commands: The install script will chug along for a while, and eventually you’ll be able…

ON HER TALK… “It’s a new vision for the global brain – deep learning with humans instead of machines.” Omoju Miller is a Machine Learning Engineer at GitHub. She holds a PhD from the University of California, Berkeley (which, apart from its academic excellence, she chose for its proximity to Skywalker Ranch). While studying for this part-time, as well being a mother, she worked as an expert at Google for its non-profit fund for Computer Science Education. We were lucky enough to catch up with her at O’Reilly’s Velocity conference in London, October 2018. Linux Format: Tell us about your data science work at GitHub. Omoju Miller: At GitHub I am part of the Machine Learning team, which is a part of the Platform Engineering team. I work on building…

Installing Sudo is just a matter of: but for it to be useful we’ll need to give our user sudo access. This involves editing the /etc/sudoers file, which for safety we’ll do using the visudo wrapper. This will check any modifications that we make, since a typo here could result in us losing sudo access. This isn’t an issue on Arch (at least while we still have root access), but can be catastrophic on other distros. Also, don’t worry if the ‘vi’ part of visudo sent a shiver down your spine – you can use whichever editor you want to edit the file (hey, I’m an editor – Ed). Let’s use Nano, for instance: There’s a whole complicated syntax to this file (the Arch Wiki will tell you all about…

In 2012 I first held a Raspberry Pi, little knowing how much it would change my life. Over these seven years, the Raspberry Pi has disrupted the market, brought the cost of a single board computer down to £35 and kept it there for all that time. But this is where the story of this generation of Raspberry Pis will end. With the release of the Compute Module 3+ we reach the end of what can be achieved with the current platform, which relies on 40nm CPUs that can only work with a maximum of 1GB RAM. For the Raspberry Pi 4 there will be a newer ARM CPU, possibly 28nm or less in size. With this new CPU there will be of course be more RAM, but what else…

If you have been hacking around with the Pi for a while, you will know of guizero, written by Laura Sach who works for the Raspberry Pi Foundation (https://lawsie.github.io/guizero). It’s a great library which simplifies the way in which we can create Tkinter-based layouts for many types of GUI application. We used it in LXF242 to create our barcode scanner/Amazon book search app. So you might be thinking, why did we choose easygui over guizero for this project? Well, it comes down to our needs. We just needed a few dialogue boxes to capture user input, and display the output from the Google search. We can do this with guizero, but it would not be three simple lines – there would be a few more lines, but still with simple…

One important element to keep in mind is stability: it’s all too easy to knock a camera, especially one mounted on a tripod. An overhead camera can also be subject to vibrations and wobbles. The result of these bumps can be a jarring distortion in your finished movie. While repeating the shot is one solution, it can be time-consuming to arrange. A better solution is to ensure that the camera is secured to a sturdy piece of gear. A tripod should have a heavy, reliable base with a low centre of gravity to avoid topples. An overhead camera should be securely connected to the base, or whatever rigging is being used to support it. You need to minimise any vibrations that might occur during the capturing of your stop-motion frames.…

Text-based file managers aren’t new; in fact, graphical managers could be considered the new kids on the block. Two of the most popular file managers for Linux users, Midnight Commander and Ranger, are command-line utilities. Unlike FFF, these feature a multi-pane interface, and some even more advanced features. For instance, you can use Midnight Commander to recover deleted files, and search for files or the content of a file as well. Unlike FFF and Ranger, however, Midnight Commander uses Emacs-style keybindings. As with FFF, you can also create bookmarks, called Hotlists, and can also connect with remote FTP clients and browse contents of archives such as RAR and ZIP – something FFF can’t do. If you’re running Ranger or Midnight Commander in a terminal emulator on top of a graphical…

1 Adjust exposure The Exposure slider creates the effect of changing a photo’s exposure time – push the slider right to lighten an underexposed photo, or left to darken it. The Contrast slider helps counter washed-out photos (push right) or narrow the range between dark and light (push left). 2 Tweak colour balance Photo looks washed out? Try pushing the Saturation slider right to inject more colour. Drag it all the way left to remove the colour so it becomes greyscale. If your camera has incorrect white balance settings, use Tint to correct them by adding more red (move it left) or green (right). 3 Additional adjustments Use the Temperature slider to make cold-looking photos warmer (or vice versa). The Shadows slider is useful for bringing out…

Do you have some pesky audio that only runs through one speaker? You can fix it by clicking the track’s drop-down box and choosing Split Stereo to Mono. A cool feature veterans may not know about is the Wave Color entry in the drop-down menu, which has four different colours, and is meant for easily differentiating between instruments. To make a split in the audio, choose the Selection tool, click where you want the split, and click Edit > Clip Boundaries > Split. Now you can move sections of the wave independently.…

Without this function working correctly, the whole export process will fail. Mod-Rewrite is used to rewrite URLs on the fly. Signs of it failing to work may be seen if the administrator clicks on a link and they get the well-known ‘404 page not found’ error. The entire permalink setup relies on mod_rewrite working correctly. If mod_rewrite fails, so will the export of the WordPress posts and therefore the final set of web pages will not work correctly. Mod_rewrite is very configurable and provides great functionality. One example is to enable URLs to be rewritten to send data to a PHP script that can use the input as part of the data to process, and the script then outputting the PHP. Also, mass migrations can use mod_ rewrite to deal…

In the walkthrough on page 78, we create a line and a circle and then make several copies of that combination for use elsewhere in the diagram. If you’re doing this sort of thing, when you’re moving a group of objects around it’s notoriously easy for them to become separated because you’ve accidentally forgotten to select one of them. It’s simple to prevent this, however. The secret is to convert those objects into what LibreOffice Draw considers to be a group. To do this, select the objects to be grouped and then select Modify > Group. Once a combination of objects is grouped in this way, it will be treated as a single object – as you’ll discover if you try to select just one constituent part of the group.…

Get the code for this project on the LXFDVD or visit www. linuxformat.com/archives and grab teh code pack. The Go way of generating WebAssembly code is much simpler compared to the Rust way, this does not mean that Go is a better language than Rust. It’s up to you to decide whether to use Go or Rust. Although creating a WebAssembly binary from Rust is a relatively straightforward process, serving that WebAssembly code using HTML and JavaScript might be challenging, especially if you aren’t familiar with JavaScript. Therefore be extra careful with your code. You can learn more about WebAssembly by visiting WebAssembly: https:// webassembly. org and https:// developer .mozilla.org/ en-US/docs/WebAssembly.…

PEN-TESTING DISTRO Kali Linux 2019.1 64- & 32-bit Once again we have only a single distribution this month, but this time we’re not neglecting our 32-bit users, with 64- and 32-bit versions of Kali Linux. It’s been a while since the last Kali release – the end of October 2018, in fact – and we like to encourage our readers to hack all the things (in a totally legal and responsible way, of course), so here we are. The main event in this new release is version 5.0 of Metasploit Framework, released in January 2019, but there’s all sorts other goodies. We’ve gone for the MATE release this time, because we like it. This is the full-fat edition with all the tools ready to go. There’s only so much you…