Índice para January 2019 em Linux Format

Jonni Bidwell Today we have desktop Linux being written about (favourably) in Forbes, people being paid to make Linux gaming more viable and a whole bunch of crafty maker-y types using FOSS to power their creativity. Even Notepad supports Unix line endings nowadays! Neil Bothwick The two outstanding occurrences in the desktop world have been GNOME 3 actually becoming usable, to the extent that even Ubuntu is using it, and KDE upgrading a major version, 4 to 5, without massive breakages. Are developers finally learning from the past? John Knight Linux has always been growing steadily, but the two most disruptive developments have been Steam and Steam Play. Gaming has been a major hurdle in desktop Linux adoption, but now for the first time many people will genuinely have no…

“Well I’ve had fun this month, what with all these lovely toys ModMyPi generously loaned me. I’ve learned how to solder, how to light up LEDs in time to music, and all sorts. Having spent the month knee-deep in sensors and desolder wick I can recommend these kind of activities. Apart from the practical side, you get a real taste for how Linux works with strange hardware and in a constrained setting. Meanwhile in European politics, we’re faced with Articles 11 and 13. Both terrible solutions to real problems. Article 11 requires that press publications be compensated when other platforms publish snippets from, or link to, their stories. That seems reasonable, until you think about what those other platforms might be. The intended target is aggregation sites, in particular Google…

The latest version of the Nextcloud desktop client brings end-to-end encryption to Nextcloud users on Linux, Windows and Mac, bringing it in line with its iOS and Android mobile clients. As the release announcement for the Nextcloud Desktop Client 2.5.0 explains (http://bit.ly/LXFNextcloud), this means that users can no longer access or share the encrypted data through a browser (due to the insecure way a browser executes code coming from the server and decrypts it). However, as the release announcement says, the Nextcloud team has worked hard to ensure that the client is now a more user-friendly experience, with server-side activities integrated better, while notifications are more prominent and easier to open and resolve. The release announcement also explains how Nextcloud’s implementation of E2EE differs from typical use cases. It now…

“Prometheus is an open source monitoring system and time series database that’s especially well-suited for monitoring dynamic cloud environments. The project has seen growing adoption over the past couple of years, leading The Linux Foundation to design a new training course for software engineers and systems administrators who want to gain a deeper understanding of using Prometheus as a means to gain better insights into their systems and services. The 25-hour course takes new Prometheus users through many of its major features, best practices and use cases. Students will be able to monitor their systems and services effectively with Prometheus upon completion on this course. This course contains 55 labs that can be completed locally, on a virtual machine or in the cloud. Because this is a hands-on course, participants…

GUILD OF MAKERS Formed in early 2018, the Guild of Makers is a world-wide group of artists, makers, creators and educators who share their skills and knowledge to better their communities. Its next conference will take place at the Auto Trader Technology Centre, Birmingham on 22 March 2019. To take part in the meeting sign up at the website: www.guildofmakers.org. SOUTHERN CALIFORNIA LINUX EXPO SCALE, as it’s more commonly know, is the largest community-run open source and free software conference in North America, and next year’s event takes place between 7 and 10 March in Pasadena, California. It features classes and seminars for everyone from beginners to experts. Now in its 16th year, SCALE is home to 150 exhibitors and 130 sessions across the four days. Visit www.socallinuxexpo.org for more…

Begin here… I read the letter from Keith Rider in the August 2018 issue and Neil’s reply with interest. I too get confused with all the gobbledegook that’s used in some articles. I’d like to put in a plea for plain English to be used whenever possible. A beginner’s section in Linux Format sounds like a good idea. I’m in my late 70s and am only interested in Linux as a productive operating system to accomplish everyday tasks. Although I’ve been using Linux for many years now I still consider myself to be a beginner. I use Linux Mint which I’ve found to be excellent. For me it just works, it’s easy to set up and I far prefer it to Windows. I assemble my own computers and find your…

For our performance tests, we used the browser and the Apache Benchmarking tool. The browser tests were quite simple, we right-clicked on our page, selected ‘Network’, refreshed the page and clicked the line which showed our URL. Once we clicked the line, we had access to the request and response headers. The headers enable us to see some performance stuff such as the server itself (that is, Nginx, Apache or Lighttpd), Keep-alive, gzip and cache control. As far as the Apache HTTP Benchmarking tool goes, we used it to test retrieving an image 25,000 times, since this is a good way to gauge a rough of idea of the requests per second that each server was capable of. To put each through their paces with set them running to fetch…

Amazon’s Kindle range may have cornered the eReader market, offering devices with lengthy battery lives and the magical ability to beam titles from their giant library in the clouds, but if you don’t want to buy into that proprietary ecosystem, you can make your own. There are a huge number of DRM-free books online. Project Gutenberg hosts thousands of classic titles that are out of copyright. There are also licenced works (for example by Cory Doctorow – see interview LXF222) that are redistributed there with permission. DRMfree ebooks can also be bought from humblebundle.com. Getting PDFs to display on the e-ink screen is likely to be a major effort, but the Epub format is widely used, and Project Gutenberg enables you to download books as plain text too, which will…

Having a portable power supply for your Pi or other devices is a great idea, and there are a few options. Of course, a standard USB powerbank (and they can store a whole lotta Coulombs these days) is fine for many applications, but there are alternatives. If you have a lot of batteries lying around check out the ModMyPi’s BattBorg. This enables you to power your Pi with four AA batteries. For more demanding situations eight AA or 9V battery attachments are available. The BattBorg defends against voltage drops, regulating power as batteries become weaker and refusing to turn it on if they’re too weak. The Ultrasonic sensor we used earlier can also be used with the Pi, but we need to be careful because the Pi’s GPIO pins don’t…

A consortium of groups that includes the Raspberry Pi Foundation has successfully secured £78 million in funding to ensure that every child in England has access to a world-leading computer education. Partnering with STEM Learning and the British Computer Society, a new National Centre for Computing Education will be established with the aim of delivering a programme to support computing teachers in primary and secondary schools. Resources from the new programme will be available for free. Furthermore, face-to-face training for teachers at priority schools will be free and at a low cost to teachers in other schools. The consortium has been tasked with three goals: establish a network of computing hubs to support teachers and schools; build a teacher training programme; and build a programme to help AS- and A-level…

We’ve covered two of the most popular tools for transforming simple text, but there are still other tools that you can use. If you use the Vimtext editor, you’ll really appreciate the DrawIt! plugin. It can be used to draw basic shapes like lines, boxes and ellipses within the text file with quick key strokes. It’s ideal if you wish to create a flowchart, or similar basic diagram. Download the DrawIt! plugin from http://bit.ly/2OHnpUm. Now navigate to the directory where you downloaded the DrawIt.vba.gz file and run the vim DrawIt.vba.gz command. This will open Vim, so press Esc and type :so % followed by :q , to install the plugin. When you now open a text file with Vim, you can start the DrawIt plugin by typing \di . The…

1 Solid background GIMPis the image editor used by Scribus. First, make sure your image has a solid background colour that can be easily differentiated by the computer from the rest of the image. White is good, or green for any users of green screen digital effects. 2 Colour to Alpha With your image open, from the main menu click Colours>Colour to Alpha, and click OK. If all goes well it should detect everything automatically and separate the object from the background. If not, you may need to use the Color Picker tool. 3 Exporting ’ your image If you don t have the option to choose Colour to Alpha, change the image to RGB mode by clicking Image>Mode> RGB. Note that you have to save your image as either…

When you’re developing your own software, it’s useful to have templates for all the commonly used constructs, such as the if statements. This is available in snippets packages – search the package list for snippets. In there you will find what you need, if not: contribute! To edit on a remote system that doesn’t have Emacs, you need Tramp. Tramp will connect to a remote system and load the file. It will also execute any shell on the remote system. When you start to open a file, the mode line shows nothing. It’s helpful to get a hint about what files you have. Install and activate idomode and your mode-line will show the files and directories at your disposal.…

By default, on most distributions, you use the elpa repository. This repository is not the biggest one though. This honour goes to the Milkypostman’s Emacs Lisp Package Archive, MELPA. The entire repository is updated every two hours, and you can see the exact time it was last compiled on the website. For the opportunity to use the huge collection that MELPA offers, you need to change your .emacs file. The code you need to add is easy to read even if you don’t know elisp. In the top of your default file, you have a (required ‘package statement). check out starts a section in the file that defines where you get your packages from, and the section ends with the (package-initialize) statement. In between, you will find the defining statement,…

In our hands-on analogue computing simulation using OpenModelica, the basic functional elements were treated as black boxes, much as they were to the original analogue computer programmers. If you want to delve a bit more into how these circuit elements work, however, you can do so by wiring up a few electronic components on a piece of breadboard. Potentiometers are trivial because you can buy them as single components. However, summers and integrators are more interesting. Both are built around an electronic circuit called an operational amplifier (op-amp) which is a high-gain amplifier that you can buy as an integrated circuit. A single op-amp is available as an eight-bit chip, while larger ICs containing multiple op-amps are available. The diagram on page 75 shows typical circuits for a three input…

Linux has a vibrant community. We’re not just users – we’re advocates. And we believe Linux is better than competing options, at least in some regards. If you’ve been around for some time, you’re probably thinking that this statement hasn’t always held true. Sure, there were always (and probably always will be) areas where Linux shone and areas where there’s been room for improvement. However, 10 or 15 years ago a side-by-side comparison with competitors didn’t often go in Linux’s favour, especially on desktops. Of course, some of these missing features were quite minor or of niche use, but the point is it was difficult to beat a commercial counterpart solely in terms of a feature set. Back then, we were using other arguments: “Linux may be missing something your…

DESKTOP ENVIRONMENT Pantheon Version: 5.0 Web: https://github.com/elementary A lot has been written about the release of Elementary OS 5.0 ‘Juno’ in general, but little about its killer feature – the shining and adorable Pantheon desktop environment (DE). In the meantime, this DE is not soldered in to eOS, but instead is available as an independent software stack for everyone. Pantheon has gained many devotees thanks to its sleek, lightweight and fully-featured DE with its own file manager, control panel, bars and panels. It was forked from Gnome 3 but evolved into an original thing with its own GUI library (Granite) that extends GTK3. The key components of Pantheon are: the Plank dock; the Switchboard settings panel; the Wingpanel top bar; the Slingshot app launcher; and a bunch of crafted accessories…

Get the full source code on the DVD or head to https://linuxformat.  com/archives?issue=245 and download it. CI/CD tools such as Jenkins ( https://jenkins.io  ) and Semaphore (https:// semaphoreci.com) will automate your builds and show you whether a Sudoku puzzle is correct or not much faster, which will make your life that much easier. To install Go, you can either use your favourite package manager or go to https://golang.org/dl/ and follow the instructions. You can find out about the version of Go you’re using by executing go version .…

I’ve been in the Linux Format hotseat for five years and it’s frankly been a wonderful, enjoyable whirlwind of a time. It’s only fair to say I entered the dingy LXF Towers as something of a Linux novice and it’s been nothing but a joy to embrace and discover the GPL’d world of the Kernel. Doing some distro hopping from Mageia to Fedora and Ubuntu, tussling with fun Nvidia proprietary drivers, rediscovering compiling programs from source, running through some LPIC and Linux Foundation sysadmin courses, constantly scratching my head at Mihalis’ coding tutorials, and meeting and chatting with readers, contributors and all manner of open source enthusiasts; there’s never been a dull moment, especially so, as the Linux kernel and its ecosystem is always evolving. A recent core movement has…

SiFive (www.sifive.com), a San Francisco-based fabless semiconductor company, has announced its lineup of its second-generation SiFive Core IP 7 processors, which are based on the open source RISC-V architecture. According to SiFive, the IP Series Cores “offer efficient performance and optimised power consumption, appropriate for supporting smart offloads of data center workloads as well as those of extremely power-efficient edge devices.” The new processors include two Linux-ready designs. The first is the U74, a single-core, Cortex-A55 processor with 128KB of L2 cache. There’s also the U74-MC, a quad-core chip with 2MB L2 cache and an S7 monitor chip. The IP 7 lineup also includes the single-core, Cortex-M7 like E76, a quad-core E76-MC, the Cortex-RB like S76 (single-core) and S76MC (quad-core). Each chip provides 64-bit memory addressing, and supports 8+1 cores…

“I’m often impressed by how complex the Linux community has become in the 22 years that I’ve been involved. Early on, it seemed that you could “know it all”. Those days are long gone. While it’s still possible to know and understand key Operating System components (virtual memory, scheduler and so on) at a reasonable level of detail, it’s no longer remotely possible to keep track of everything. I’ve found this particularly true lately because I’ve been playing catch-up with understanding the internals (from the kernel side) of containers. This is something that turns out to be pretty fascinating, and which I’ll probably devote column space to in the not-too distant future. This column acts as a prompt for me to stay up to date. It encourages me to read…

“Do you have a written plan for how your business’s Linux infrastructure will evolve over time? If not, then you should have. Let me explain why… A documented review every six months will help you spend any IT budget more effectively. When we’re reactive – that is, solving problems because they’re hurting us right now – we seldom implement a considered solution. Here’s a common example. When Server A is short of disk space, we fit a bigger disk. Problem solved – next! But when you review your infrastructure and you note that three servers will require more disk space in the next year or so, you may consider consolidating all disk storage to one place. More scalable. Easier to back up. This is joined-up thinking in action. Of course,…

Bitwarden, the popular platform-agnostic open source password manager, which has versions available for Linux, Windows and Mac, as well as Android, iOS and even the command line, hired Cure 53, a security company from Germany, to run an audit on the security of its software and the technology it uses. In the interests of transparency the developer has released a PDF document (which you can view at http://bit.ly/LXFBitwardenAudit) that lists Cure 53’s findings. The company did find several issues, which are highlighted in the PDF, and which the Bitwarden team has addressed, which includes changing how login URIs work and limiting permitted protocols. The software was also criticised how the application accepts any master password, with the only demand being it has to be at least eight characters in length.…

Linux Mint 19 Q I’ve recently decided to try Linux and installed Linux Mint 18.3 in a dual-boot system with Windows 7 on a Lenovo ThinkPad T410. I’ve not got around to using Linux apart from doing a couple of updates and now we’re presented with Linux Mint 19, so I thought I might as well upgrade now before I had accumulated any personal files. I read the instructions published by Clem on the Community channel and decided that I was too ignorant to carry out the full upgrade and thought I would just use the disk provided with LXF240 and do a fresh install. However, on booting up the hard disk it recognises that there are two existing operating systems, but offers to install Linux Mint 19 in addition…

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…

Send your thoughts to the Linux Format dungeon server at linuxformat@futurenet.com and secure your chance to win an amazing 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.…

The Manjaro project occasionally produces limited-edition hardware for its ardent community of users. The latest of these Manjarocertified devices is the Bladebook Fall 2018. These devices sport a 13.3-inch FHD IPS display and are powered by the Intel Celeron N3450 processor along with Intel HD Graphics 500. They use a 64GB eMMC disk as their primary storage device and come with 6GB of DDR3L RAM and an 8000mAh battery that can power the portable computer for up to eight hours. Manjaro has put up 100 units of the Bladebook in its online shop and you can get one for CHF 259.05, which is just a shade under £200. Surprisingly, instead of the marquee Xfce edition, the Bladebook runs the KDE-flavoured Manjaro. This is the KDE edition that ships with Plasma…

“We’re going to test varying examples of content from the most basic to more elaborate websites” Much of the the World Wide Web is used to display readable web pages. From a typical web development point of view, most websites and web applications are built with a combination of web coding languages; like HTML, CSS, JavaScript, PHP, Java and mySQL to name but a few of the most common ones. Going into details a little deeper, web pages can be basic, speed optimised web pages, or complex web applications with lots of bells and whistles like slideshows, data reporting and e-commerce featurest. As websites comes in all shapes and sizes, it cannot be stressed enough how essential it is to know which web server delivers the best performance for the…

Since most websites will use a server-side language, such as a WordPress installation or basic code to handle a contact form from HTML, let’s have a look at how easy that is to implement. Extending web servers is easier with some than others. However, from a simplicity standpoint, both Apache and Lighttpd make it very easy to check modules and enable them as needed. For example, one such module that is not enabled by default in Apache is mod_cache. Nginx, on the contrary does offer plenty from the first go, but single commands to enable and disable them are not part of the program. With Nginx, adding and configuring modules runs beyond novice usage. Openlitespeed is not as straightforward as Apache or Lighttpd either, but they both can at least…

Sometimes it's good to talk to the Arduino from Python, rather than trying to do it all in the IDE. Having a Raspberry Pi work in tandem with an Arduino is useful. We still need the IDE to upload sketches to the Arduino, but we can do more with the data from the Python side. All we need to do is connect the two boards with a USB cable. We communicate via serial link over USB. On the Python side we need the serial module (installed by default) and the device name of our serial link (check the output of ls /dev/tty* ). Set things up with: We can then read from and write to the Arduino using the object s1 . The following reads a single byte and then…

Thanks to most smartphones in the world standardising on micro-USB connections (except those made by a certain fruity company), it’s easy to pick up a power supply for your Pi. It's powered by the same thing after all. However, one should be careful: many of the cheaper phone chargers aren’t capable of providing the voltage required to reliably power the Pi. The same thing is true for the USB ports on your computer. This is especially true for the Pi 3s (and newer 3 B+s), whose faster SoCs and wireless chips need extra voltage. Many unsuspecting users of these devices have been traumatised by the appearance of a lightning bolt in the top right of the screen. This signifies a low voltage and that the Pi has throttled its CPU…

Part of the power of Kubernetes is the abstraction it offers. From a developer’s perspective, they develop the application to run in a Docker container. Docker doesn’t care whether it’s running on Windows, Linux or some other operating system. That same Docker container can be taken from the developer’s MacBook and run under Kubernetes without any modification. The Kubernetes installation itself can be a single machine. Of course, a lot of the benefits of Kubernetes won’t be available: there will be no auto-scaling; there’s an obvious single point of failure, and so on. As a proof of concept in a test environment, though, it works. Once you’re ready for production, you can run in-house or on a Cloud provider such as AWS or Google Cloud. The Cloud providers have some…

Thanks largely to the Raspberry Pi, Python has seen a surge in interest and has been used to put together projects as simple as flashing LEDs, to making strides in machine learning and artificial intelligence. The power of Python is twofold. The language is accessible and easy to read, which means that new users can understand the flow of an algorithm. But more importantly, Python has a passionate community of communities. Did you think that Python was just for system administrators? Well, think again. Python is truly for everyone. From the schoolchild or young students taking their first steps with a typed language, who need the clarity and ease of use in order to learn and see the results of their labour. To the Makers who aren’t necessarily coders and…

For this issue’s project we shall use Pushover, a notification service for all devices along with the humble Raspberry Pi to create an intrusion system that will detect movement using an infrared sensor and take a picture of the intruder using the official Raspberry Pi camera. And all of this will then be sent to all of our devices using the Pushover software. Our first step in building the hardware is to connect the official camera to the Camera port, located between the HDMI and Ethernet port (Pi Zero W users, your camera connection is on the edge of the board.) With the Raspberry Pi turned off, gently lift the tabs until the port is open. Then insert the ribbon cable of the camera so that the blue section is…

To cast to your Raspberry Pi from your Android phone or tablet (a reliable iPhone or iPad alternative has yet to be released), you’ll need Raspicast, from the Google Play store. Once installed (with all permissions granted), ensure your phone and the Raspberry Pi are connected to the same network. You can’t use Raspicast to stream media from your phone to a Raspberry Pi otherwise. Within the app you’ll find standard controls (play/pause, and stop) a file browser, Cast button, and some options that will change how Raspicast streams your content. For example, should you want to replay the current file, open the menu and check the Repeat box. Meanwhile, tap Audio output to ensure that the audio is streamed in the correct way. For video, this will typically be…

Guides are a tricky thing in Scribus. If you open the main menu and click View> Show Guides, it turns on the big ugly lines that show where everything goes. This may or may not be enabled by default according to the whims of the document. Turning them on or off will probably result in nothing with a brand new document, as they are generally things you need to define yourself. For new documents, Page>Snap to Guides is less useful than Snap to Grid, because it will only snap to the page borders and not the columns – one would assume Snap to Guides would work with columns from the outset. Unfortunately, if you want to have your frames snap to columns, you will need to enter these manually in…

Vimgolfis a way to practise editing tasks in Vim. This article covers Emacsso what does this have to do with it? Well, you can run Vimgolf against Emacs. The exercises will be the same and you can compare against other Emacs users. You can also compare to the Vimscores and see which is the best editor. To participate you register on www.vimgolf.com and use the command line tools to get started. The package is available on MELPA or you can download the vimgolf.el file from GitHub and start it using M-x vimgolf . The minibuffer will ask for a challenge ID. Pick it up from the webpage – the number is in the address bar when you’re viewing the challenge. When you’re in the mood, it will be more direct…

An important difference between the two is that any problem can be solved on any digital computer, but the computing time increases with the number of differential equations. Using analogue techniques, the computing time is independent of the number of differential equations but the size of the computer – that is, how many summers and integrators it has – increases with the size of the problem. Back in the 60s and 70s, large analogue computers were used for large problems when digital computers were too slow. Another key difference is ease of use. Writing software is comparatively quick compared to wiring up analogue computers; take into account the job of scaling circuits to ensure that voltages are never exceeded. Changing the operation of a digital computer is a simple matter…

There are some rules about benchmark writing in Go. First, the go test subcommand is responsible for benchmarking a program. Then, it’s considered best practice for benchmark functions to be included in Go files that end with _test.go. All benchmark function names should begin with Benchmark – a function that begins with a lowercase B isn’t treated as a benchmark function by Go. Additionally, benchmark functions must have a given signature, which means that benchmark functions should accept a *testing.B parameter only and return no values. Finally, the package that contains benchmark functions must include the “testing” standard Go package. Benchmarking functions are executed with commands similar to the following: The value of the -bench parameter specifies the benchmark functions that will be executed using regular expressions. The . value…

OUR EXPERT John Schwartzman is a software engineering consultant to business and government. He also teaches computer science at a local college. Bash does a great job keeping track of all the commands you’ve entered on the command line. Combined with grep, you can usually manage to find that elusive command you want to reenter. Using a GUI program to help manage your command history may be anathema to those who pride themselves on doing everything on the command line. (If that’s you, stop reading now!) In this tutorial, you’re going to work with Qt’s (pronounced cute) graphical user interface (GUI) creator, Qt 5 Designer. If you use KDE, Qt is what powers its GUI. Qt works on Mac and Windows, as well as Linux and Unix. The point of…

Note how you spell your widget names. The Push Button widget that closes the dialog is named ‘pushButton Close’. The List Widget is called ‘listWidget’. The Line Edit widget is named ‘lineEditTrim’. Make sure that the names you use in Qt 5 Designer match the names in the code you add to your Python program. Python depends on proper indentation. The standard is to use four spaces per tab and to have the tab key emit four spaces. Your code editor knows all about this. Don’t mix tabs and spaces in your code: the Python interpreter will get confused and will tell you so with cryptic messages. If you set your code editor so that the tab key emits spaces, that won’t be an issue.…

At the 2018 OpenStack Summit in Berlin (www.openstack.org), Mark Shuttleworth, the CEO and founder of Canonical, announced that Ubuntu 18.04 LTS, the Long Term Support release of Canonicals’ popular Debian-based distro, will now have support for up to 10 years, double the usual length of time for Ubuntu LTS releases. As Server Watch reports (http://bit.ly/LXFServerWatch), Mark announced the 10-year support window and said that, “In part because of the very long time horizons in some of industries like financial services and telecommunications but also from IoT where manufacturing lines for example are being deployed that will be in production for at least a decade .” Ubuntu 18.04 LTS was released on 26 April, so anyone with it installed can expect support until 26 April, 2028. The Canonical CEO was effusive…

“Zink is an OpenGL implementation on top of Vulkan. More specifically, Zink is a Mesa Gallium driver that leverages the OpenGL implementation in the Mesa 3D graphics library to give hardware accelerated OpenGL, when only a Vulkan driver is available. With the well-established OpenGL being around since 1992, and Vulkan becoming mainstream, Zink aims to simplify the graphics stack, and cut through the growing complexity of two APIs for essentially the same hardware functionality. In addition, Zink should hopefully lessen the workload for future GPU drivers, enable more integration, as well as support application porting in Vulkan. Zink has only been tested on Linux; however, it should run on any other OS that supports Vulkan, apart from the fact that some window-system integration coding might be needed. Zink currently requires…

Recent development kernels include support for a processor feature known as STIBP (single threaded indirect branch predictors). This is part of the x86 mitigation for Spectre-v2. As a refresher, Spectre-v2 affects a part of modern microprocessors known as the indirect branch predictor. This is hardware that attempts to guess the target address of branches (jumps), such as through function pointers (C) or virtual methods (C++). Many x86 processors implement what’s known as SMT (Symmetric Multi-Threading) in which they create the illusion of having more cores by duplicating some processor resources into pairs of “logical” threads. In Intel and AMD designs, there are two threads per physical core. Together, they have the same performance as one core, but logically are seen by the OS as two separate ones, and careful scheduling…

PALE MOON 28.2.0 A major update for this open source Goanna-based web browser that’s available on both Linux and Windows, has been released. Pale Moon has been designed to focus on efficiency and customisation, and was forked off from its Firefox code a few years ago. The new version brings a number of bug fixes, as well as general improvements to the user experience. You can find out all about the new version from the change log at http://bit.ly/LXFPaleMoon. VOYAGER LIVE 18.10 This latest version of the Ubuntu-based distro ditches the Xfce desktop in favour of GNOME, and uses Ubuntu 18.10 as its basis. According to a translation of the release announcement, the switch to GNOME 10 years after the project dropped it is that the GNOME Shell is now…

Build Brighton Thursday evenings is open night. www.buildbrighton.com Cornwall Tech Jam Second Saturday of the month alternating between Bodmin and Camborne. www.cornwalltechjam.uk Huddersfield Raspberry Jam Meet every month at Huddersfield Library, typically on the fourth Saturday of each month. https://huddersfieldraspberryjam.co.uk Horsham Raspberry Jam Park side, 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 rLab Reading Hackspace Unit C1, Weldale ST, Reading, Open Sessions Wednesday from 7pm. http://rlab.org.uk Glasgow Makers and Hardware Hackers Mitchell Library, Glasgow. https://m.facebook.com/groups/115303729096198 Teesside Hackspace Tuesday Evenings at Teesside Hackspace. www.teessidehackspace.org.uk…

D isk space is one of those things you always think you have plenty of… until you run out. Sometimes disk space can disappear for no obvious reason so you need to be able to find what’s using it. The du(disk usage) program is the standard tool for this, but it’s a bit fiddly to use in this situation. Enter ncdu, a curses terminal program that displays the disk usage of a directory, sorted by size, and enables you to drill down through the directories until you find the culprit – possible a runaway log file. It also makes it possible to delete it. Simply pass it the path you want to examine, although it’s worth adding the -x flag to keep within the current filesystem. This is especially true…

I’m Mad-geia! Feeling the need to experiment with different operating systems, I installed Mageia 6 on a spare hard drive and now I’m writing this partly as a warning to others… If you install this system, as soon as you’ve rebooted, locate the System Lock screen and untick the two pre-ticked boxes. If you don’t and you leave the screen unused for more than five minutes the system will lock up and there’s no reactivate option. A message will even appear telling you it’s a known problem and suggesting a roundabout way out, which didn’t work for me. The next problem is that you can’t install updates. The reason is that the system can’t locate the required update software due to two pre-ticked boxes telling it to look in the…

Since our Linux box has the ability to build and setup web servers in minutes, our local machine is the device we used in this tutorial to test our servers. In order to complete our testing, all we really need is access to the Internet while installing our building and testing software. Once that has been done, we can manage without it for our testing needs. Since browsers are the main way users experience server performance these days browser-response times will be a key test, we can test loads and delivery to produce some very useful numbers. In addition to browsers, we’ll use the Apache Benchmark test suite, which delivers some very useful data, this will help us gauge the efficiency of our servers and why some are better in…

Web servers will be installed via the command line. Some installations are very simple one-liners that use apt-get install while others need to be installed from source using a few extra commands. Once installed, the servers can be used to quickly display a default web page. Since we will test our servers with the server-side language PHP and mySQL, we will see how easily they can be used with each server. Looking into details, we will see which software works easiest with basic commands or with the aid of very basic text editing to config files. On top of that, we will look at configuring each server so that it runs more efficiently and helps us get the results we need: a fast-loading website that won’t leave potential viewers so…

When choosing our list of servers, we wanted to compare the most popular web servers, as there are very good reasons they’re used; such as reliability over many years. However, there is a very long list of other web servers that can be used for testing web apps and deploying live websites such as Tengine, Cherokee, IdeaWebServer, Cowboy and Monkey. Although we were hoping to find some gold in the smaller players, our search came up empty. Almost all of the others we tried were not worth the effort. In many cases, vendor websites looked abandoned and instructions failed. Often, the packages did not exist and files were missing when building from source. When a package did work, it would have taken too long to configure to be useful. We…

Pulse-width modulation is a method of encoding information as digital signals. Using the frequency of the clock generator we can encode data based on how much time the signal is low, compared to how it is high. If we send a sequence that sends a 1 then a 0 (for the same time period) and repeats, then that looks like a value of one half. This is known as a 50 per cent duty cycle. By changing the duty cycle we can achieve a variety of in-between values, so we can approximate an analogue signal. This method is used to dim LEDs, to adjust the position of a servo or any number of other things. PWM can also be used to mimic an analogue signal, for example having an output…

1 Mount the sensor Carefully bend the bracket to form a 90 degree angle. Try to apply the force evenly so that the bottom edge doesn’t twist. You’ll be lucky if you get away with bending this back again. Screw in the ultrasonic sensor with the connectors facing upwards, and secure with the four small bolts provided. 2 Fit to servo Attach the circular fixture to the top of the servo and then screw the mounted sensor in place. Don’t worry about it facing straight ahead here. The servo may not be at its resting position and it’s relatively straightforward to align it from the Arduino IDE and then adjust the sensor to look dead ahead. 3 Connect the cables Attach the cable to the sensor and connect the jumper…

If you’re not familiar with Docker (also see tutorials in LXF237) start here: https://docs.docker.com/get-started. There’s an interactive, tutorial on deploying and scaling an app here: https://kubernetes.io/docs/tutorials/kubernetes-basics. And see https://kubernetes.io/docs/setup/scratch for how to build a cluster. You can play with a free Kubernetes cluster at https://tryk8s.com. Finally, you can pore over a long, technical paper with an excellent overview of Google’s use of Borg and how that influenced the design of Kubernetes here: https://storage.googleapis.com/pub-tools-public-publication-data/pdf/43438.pdf.…

In this project we created our own Pushover application that sends alerts to a waiting Android app. But there are other ways to interact with Pushover. There are apps for Android, iOS and for Chrome, Firefox and Safari. We tested the Chrome application, which can be installed from https://pushover.net/clients and it worked flawlessly. There’s also a dedicated system tray application that works pretty well with Pushover. The unofficial Pullover application is handy to receive the alerts from our device, but sadly it can’t display images. That said, the app is handy for receiving text alerts, for example remote sensor triggers such as temperature, pressure and light levels. Pullover can be found at https://github.com/cgrossde/Pullover and it works with Linux, Mac and Windows devices. Pushover has an extensive API (Application Programming Interface)…

If you click View>Show Grid, an overlay in the style of technical graph-paper will appear, with big cubes (the major grid) containing smaller cubes (the minor grid). You can either use this grid as a simple visual guide, enabling you to still draw freehand and place things where you like, or you can make objects rigidly “snap” to it. If you’re making a garish magazine with free-flowing objects then leave it as it is. But if you’re making something quite conservative with many pages to produce, you want the snap function. By default the grid will simply act as a visual guide, but if you want to enable the snap function, from the main menu choose Page>Snap to Grid. However, the default grid sizes are a bit weird and the…

The big flame-war about editors is usually over Vim vs Emacs. Where do you belong? The Vim camp may feel a little lost when using the Emacs editor. Remember, though, that even on the Vimgolf site, you can see that in some cases Emacs has superior scores but not always. This is where evil mode comes in! In evil mode the key-bindings works just like in Vim. To get it running, you need to install the evil mode and activate it. The easiest way to do that is to open the package list in Emacs, find evil, hit Enter and click or choose Install. There are two issues: the first is that this requires the MELPA package (see boxout, above right), and the second is that you have 68 versions.…

Analogue computers played a key role in sending man to the moon. They were used for lunar landing simulations during the Apollo programme and continued to play a role at NASA until the early 80s. The earliest known analogue computer is known as the Antikythera Mechanism. It was found on the seabed off the coast of the Greek island Antikythera and is about 2,000 years old. It was able to predict astronomical events, including eclipses. If you fancy getting to grips with a real analogue computer and you’re handy with a soldering iron, there are several designs available online for amateur experimenters. For example, the one at www.grappendorf. net/projects/ analog-computer/provides  full circuit diagrams and links to PCB layouts.…

Keeping programs running once you log out is perhaps the most common use-case for tmuxand the GNU screen. These aren’t the only options for achieving this, however. When you log out, Linux closes the terminal, or more likely these days, a pseudo terminal device. Processes that had it as a controlling terminal – that is, interactive programs you started during the session – then receive a SIGHUP. By default, this signal causes the process to terminate. There are ways to override the default: either ignore the signal if you’re the program’s author; or just prefix the invocation with nohup . This simple tool redirects standard I/O streams from the terminal (the output typically goes to nohup.out ) effectively preventing SIGHUP from being sent. Start the program with & to make…

OUR EXPERT Mihalis Tsoukalos is the author of Go Systems Programming and Mastering Go. You can reach him at@mactsouk. Struggling with your Sudoku puzzles? Then we’re here to make the life easier, although you’ll have to do some Go programming along the way, so… Although the difficulty of a Sudoku puzzle depends on how many numbers you have when you are solving it, this tutorial won’t be dealing with that aspect of designing Sudoku puzzles. We’ll be coding two versions of the Go program, but both versions read the Sudoku board from a text file. The main difference between the two will be the way they access the elements of the Go slice that stores the Sudoku puzzle. Our final step will be benchmarking each to find out which one…

Although this tutorial presents code that deals with verifying Sudoku puzzles which have already been solved, there are algorithms and techniques that can help you solve an unsolved Sudoku puzzle or create a new Sudoku puzzle. As you can imagine, these algorithms and techniques are much more sophisticated than the ones presented here, require more computing power and have more rules and conditions. The main difficulty when creating a new Sudoku grid is making sure that the Sudoku puzzle is solvable. Therefore, you shouldn’t just put some numbers on a Sudoku board and expect it to be solvable! Generally speaking, one way of solving a Sudoku puzzle is to keep trying to solve it until you have a deadlock. You should then go back, pick a different value and keep…

On the DVD, you’ll find HistoryDlg5.ui, historyDlg5.py, HistoryDlg6.ui , historyDlg6.py and historyDlg7.py. They all had their starting points in Qt5 Designer because it’s so much easier to use a GUI tool than it is to create a GUI manually. It’s probably not even practical to create anything much larger than historyDlg6.ui manually. HistoryDlg6.ui was created by disabling a few push buttons and adding a widget to HistoryDlg5.ui using Qt5 Designer . HistoryDlg6.py was creating by using the pyuic5 utility on HistoryDlg6.ui ( pyuic5 -x -o historyDlg6.py HistoryDlg6.ui ). This file contains an enhanced version of what you’ve done in this tutorial. historydlg6.py enables and disables buttons as appropriate, and capitalises and restores the newest to oldest history order with a toggle button. The screenshot on page 95 shows the…

Your package manager probably has PyQt 5 available. It may show up in your package manager as the installation pattern Qt 5 Development. The packages you want are python-qt5-utils, python3-qt5, python3-qt5-devel and if you’re using Python2, python2-qt5 and python2-qt5-devel. And, of course, you’ll need the Python language as well. Python is a powerful and easy to learn programming language. Many colleges are now using Python as their introductory programming course. Python has a “batteries included” philosophy: it comes with a large library of useful modules. historyDlg5.py is written so that it will run on both Python 2 and on Python 3, so that it doesn’t matter which version you’re using. If you’re not currently using Python, look for the installation pattern Python 3 in your package manager. Python 3…