Linux FormatApril 2019的目錄

Christian Cawley Saving up my pocket money (usually reserved for a Mastertronic budget game) for an Action Replay cartridge and ordering it from the pages of Zzap!64 magazine. A month later it was waiting when I came home from school, ready to plug into my C64 and, um, help me cheat at games. Happy times. Nick Peers I remember the joy of finally knowing I was to get a ZX Spectrum+ for a combined 13th birthday/Christmas present. Sadly I found the present hidden under my grandparents’ bed, and was caught with my legs sticking out as I gazed on it lovingly for the umpteenth time. Les Pounder In the 1980s and 1990s I had an Amiga 500. It’s on the Amiga where I cut my teeth, learning the command line…

“I think the technology sector is an amazing place to work. I’ve done so for more years that I’d like to admit, and it still fascinates me. The relentless march of progress, new areas to explore… it’s never-ending. Most techie people I know have a list of technologies they’d like to play with. There tend to be two goals: let’s understand this, and let’s work out where we can use this at work. Understanding it is good: the broader our knowledge of IT, the more value we can bring to the businesses we work for or with. When it comes to “where can we use this”, though, we need to slow down. Business IT solutions start with a problem that is defined in terms of requirements. Starting with the solution…

System76 has shared initial work to support Coreboot on its Kaby Lake-and Whiskey Lake-based laptops. Coreboot replaces the proprietary firmware that ships with motherboards and CPUs, circumventing most of the controversial Intel Management Engine (ME). The work, by Felix Singer, aims to support the Galago Pro and Darter Pro laptops and is available on the System76 GitHub at http://bit.ly/lxf248core . Also hosted on this GitHub is coreboot-collector, a utility written in Rust for gathering motherboard information to assist with Coreboot installs.…

“I always enjoy seeing the excitement that comes from building your first Linux kernel. Building a kernel can seem like a very daunting and difficult task, filled with many opportunities for painful mistakes, but this need not be the case. To start with, modern hardware virtualisation is now built into almost every laptop, so it is no longer necessary to actually run a test kernel on your bare metal. Whether through KVM, VirtualBox, VMWare or one of many other freely available solutions, you can easily install a throwaway VM running a test distro and build your first kernel inside. In fact, this is a great time to try out one of the bleeding-edge distros, such as Fedora’s Rawhide, or OpenSuSE Factory. These will already include the latest tooling, including compilers…

Borderless boot menu Q As a newcomer to Linux, I have recently installed Linux Mint 19 in a dual-boot system with Windows 7, and have fallen in love with it! However, not liking the basic GRUB screen, I have used Grub Customizer to personalise it, including a rather nice background image – only to find that my image is spoiled by the ugly frame around the choices of OS. I have searched online for a way to disable this, but without success. Then I noticed that the GRUB screen on your coverdiscs looks exactly the way I want mine to look – without a frame. Would you care to share your secret? Roger Read A The frame around the menu is part of the standard GRUB menu and cannot be…

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…

While PureOS comes preinstalled on the Librem 13, it might not be to your liking. For example, Steam is a problem to install, as are several other digital distribution services. The built-in Software tool, meanwhile, offers apps and games that won’t run. This might be down to the reliance on open source drivers, but regardless, it can prove to be a bit of a problem. Our test device proved impervious to any form of serious benchmarking, partially due to PureOS, and partially to the Intel HD 620 GPU. As such, while the hardware itself is powerful enough, it makes sense to opt for an alternative Linux distro. PureOS is based on Debian, which makes this, Ubuntu, and most other members of that Linux family strong replacements. Rather than replacing PureOS…

So-called paint packages are the most commonly used type of graphic editing software. But while they’re perfect for touching up photos, they’re far from ideal for creating diagrams and illustrations. The snag with using paint software for this purpose is that they work at the level of pixels. A much better solution is to use a drawing package, otherwise known as vector-based graphics software, which works at the level of picture elements such as lines, circles, boxes and text. The waters have been muddied by some paint software appearing to offer similar functionality, but if you want full control over the drawing process, there’s no better option than vector-based software. This type of software can used by graphics artists, but our assumption here is that most LXF readers will have…

Although we’re looking at vector-based graphics packages instead of the bitmapped software used for editing photos, there are times when some limited support of bitmaps is useful, say for including photos of staff in an organisational chart. All the software reviewed here enables you to import bitmapped images for this purpose, and the basic editing functions available enable you to move, resize and rotate them. Some software also enables you to crop images but, even if there’s no specific crop bitmap function, with most reasonably featured vector graphics software you’ll be able to find some way of achieving this. While we wouldn’t recommend using any vector-based software for dedicated image editing use – something like GIMP is far more appropriate – some of the packages included here do offer a…

Most 8-bit machines relied on the CPU for audio, making do with simple ‘bleep bloop’ noises, the Commodore was designed to have a strong, dedicated sound chip from the beginning – the SID 6581. The SID (Sound Interface Device) was developed by a musician, Ensoniq’s Robert Yannes. Distinctly unimpressed with the primitive existing computer audio, he designed a multi-channel audio chip that simply destroyed the competition. Sporting three channels, each has an ADSR envelope generator and the ability to apply audio filters. Interestingly, a by-product of hardware imperfections resulted in effectively another channel, allowing for 4-bit digital samples, which was often used to synthesise speech. The SID outlived the Commodore 64 and would become the basis for many pieces of pro music hardware, though since production has stopped any remaining…

SPECIFICATION CPU: Motorola 68000 at 8MHz RAM: 512K (up to 4MB) Graphics: 320x200 with 16 out of 512 colours, 640x200 with 4 out of 512 colours, 640x400 monochrome Sound: Yamaha YM2149F three-voice squarewave plus one-voice white noise OS: GEM, via Atari TOS Storage: 3.5-inch floppy, optional HDD Released: June 1985 Launch Price: £399 (base model) Production: 1985-1993 Worldwide sales: 2.2 million Regarded by many as the first proper 16-bit computer, the ST was a powerhouse bargain for its time. Jack Tramiel wanted to make something that would walk over the Mac and IBM PC for a much lower price. Arriving a month before the Amiga, prices were around $500 cheaper than the upcoming Commodore Amiga 1000 equivalents. For an operating system, Atari rejected Microsoft’s unfinished version of Windows in favour…

Used all over the world, DOSBox is a DOS emulator that runs everything and is available on a zillion platforms. It will undoubtedly be in your distro’s repositories, and you won’t need a BIOS file for it. However, it does take a few steps to get it going like a normal DOS machine. We won’t show you how to use DOS, but we will show you how to set up your C: drive. DOS used a simple file called autoexec.bat to run its startup commands, but DOSBox doesn’t actually have this file, nor does it start with a C: drive. You need to edit its config file to emulate autoexec.bat and assign a C: drive. For this demonstration we’ll assume you’re putting all your files in a folder called /dosbox…

Maplin might have shut up (physical) shop, but there’s now a new store where you can go to sate your hunger for everything Pi and maker-based goodness: none other than the official Raspberry Pi Store in Cambridge. Wander down the Grand Arcade in the centre of Cambridge and among all the Sports Direct buyouts and store closures, it’s refreshing to see a brand opening a high street shop for the first time, from the Raspberry Pi Foundation. Described as an ‘experimental space’, the Pi shop is in Cambridge because that’s where the Foundation is based. It’s also a hub of tech, science and study, so the shop should find plenty of customers. Founder Eben Upton told the BBC it’ll give the computer’s “loyal and highly engaged community” a physical space…

Crontab field separation has the first field holding the minute at which to run, from 0-59. The second field is the hour to run, 0-23. The day of the month is the next field, followed by the month field, limited to 12 numeric values. The day of the week field is next, with values starting at 0 for Sunday. At the end is the command string – in other words, what you want to automate – suffixed with the string >/dev/ null 2>&1. This string of text is used to ensure any output generated by the command has a place to go. Commands run at the CLI have an output. If the command is wordy, it sends the text to STDOUT, ‘Standard Output’ – the screen. The error output STDERR…

While this tutorial has been all about text-to-speech software, at the other end of that spectrum is voice recognition. In a world driven by Alexa, Cortana and the like, it shouldn’t come as any surprise that voice recognition on Linux is also being actively pursued. Unfortunately, there doesn’t as yet exist a perfect solution to serve your every command. The past decade has witnessed the rise, and sad demise, of various voice recognition solutions for Linux. The Wikipedia page on speech recognition software for Linux https://en.wikipedia.org/wiki/Speech_recognition_software_for_Linux has an incomplete list of various projects that are working towards this goal, and although not officially dead, many (see Roundup LXF188) of these applications have not witnessed a new release in several years. One of most popular voice recognition systems today is the…

If the VM isn’t frequently used, the IP address served by DHCP may change. To resolve this, exclude the IP from the router as mentioned. Setting up the IP is as simple as opening /etc/network/interfaces as the root user and modifying the line that ends in dhcp, changing it to static. Doing this also means the server needs to know its IP details. Three lines are needed: to configure the IP address, the network mask, the gateway and the required DNS entries. The first line should be addr= followed by the IP address of the VM. The second line netmask is the network mask. For example netmask=255.255.255.0. The final entry is gateway and this should be the default gateway being used, again in the form of gateway=192.168.0.1, substituting your default…

Spend some time configuring either webcron or cron to automate regular maintenance tasks like database clean-ups, and to periodically send out activity emails – especially when using external storage. Use the External User Support app to configure additional user backends. There’s also the LDAP User and Group Backend app for hooking up Nextcloud with an existing LDAP server. The File Access Control app has an intuitive interface that enables you to define complex rules for accessing files and folders housed inside the Nextcloud server.…

WINDOWS EMULATOR Wine Version: 4.0 Web: www.winehq.org The Wine development team, still being led by project founder Alexander Julliard, publishes big releases roughly once a year, which matches the frequency of our Wine reviews at LXF. In the past we used to admire the possibilities that Wine opens for everyone who needs to run Windows-only productivity applications, and that’s still true today. But while the seamless running of Windows executables in Linux keeps being amazing, the focus of Wine development has long shifted towards running high-end games. Wine 4.0 is a major new version with some tasty news for gamers. It boasts initial Vulkan graphics API, early Direct3D 12 support and Direct3D Multi-Threaded Command Stream (CSMT) enabled by default for better performance. This is definitely a good addition to DXVK…

Nostalgia is a powerful drug. It’s easy to get caught up in whimsical silver-lined memories of the past, forgetting all the advances and advantages the present holds – but when did that ever stop us before? For one issue only, we’re going to bask in nostalgia and go full retro – looking at how open source with the Linux kernel can help us not just relive computing systems of old, but enjoy classic games, learn about historical architectures, revive old languages and run unsupported software. While it’s often retro gaming that springs to mind, retro computing is far more than that and we felt it was essential that we covered the whole, er, spectrum of computing history, including systems that helped establish computing in the home – from the Apple…

Western Digital announced it would be building its own processor, based on the open source RISC-V architecture, back in December 2018. Designs for the SweRV cores are now available on the company’s GitHub at https://github.com/westerndigitalcorporation/swerv_eh1 , under an Apache 2.0 licence. These Register-Transfer Level (RTL) abstractions enable advanced users to model the CPU using the System on a Chip (SoC) modelling tool Verilator. WD stated that its rather ambitious goal is to ship one billion RISC-V cores per year through its comprehensive array of storage products. It also plans to release a FOSS RISC-V instruction set simulator, which will undoubtedly be of benefit to the wider community in the long run. Specs-wise, the SweRV core is a 32-bit in-order affair which can be clocked up to 1.8GHz and is built…

Grants Paragon Software right to furnish drivers upon OEMs. Back in October 2018, Microsoft joined the Open Invention Network, granting it royalty-free access to some 60,000 patents. Missing from this portfolio, however, was the exFAT patent that covers the modernised version of the FAT filesystem which originated in MS-DOS. ExFAT is valuable IP – it’s used for high-capacity USB drives and SD cards, and commonly supported on set-top boxes, NAS boxes, media centres and the like – so it’s unsurprising MS didn’t offer it as a charitable donation. But now it has authorised Paragon Software Group the right to “provide licensed exFAT implementations to their customers without a direct license from Microsoft”, said Microsoft’s VP for IP Licensing Micky Minhas. Paragon and Microsoft already had a partnership in place that…

UBUNTU 18.04.2 Those who prefer to stick with the LTS releases of Ubuntu will be thrilled that the second point release is now available, sporting an all new Hardware Enablement (HWE) stack. Besides the new 4.18 kernel and applications, a number of performance fixes for Gnome are included. Anyone who installed the first point release will get this one without any intervention, but those who installed the first 18.04 release should follow the instructions at http://bit.ly/lxf248ubuntu. RIOT 1.0 Riot, the FOSS flagship chat client for the decentralised Matrix architecture (https://matrix.org), has hit version 1.0. This long-awaited release brings a stylish new user interface, readability improvements and, because no one likes bright and cheery, a dark theme. Riot now features automatic key backups for encrypted conversations, as well as the ability…

Linus Torvalds announced what is likely to be the final RC (Release Candidate) for the 5.0 kernel cycle. Linux 5.0-rc7 includes relatively few driver and platform fixes, typically for this late in the release process. As we covered previously, the new major version numbering is more about convenience rather than some earth-shattering new set of features. In fact, 5.0 is on the smaller side compared to other recent releases. Perhaps the most interesting features added to 5.0 are the Energy Aware Scheduler (EAS) patches. These will particularly benefit mobile device performance, including Android phones. “PERHAPS THE MOST INTERESTING FEATURES IN 5.0 ARE THE ENERGY AWARE SCHEDULER PATCHES” EAS patches have been under development for many years. For a while it wasn’t entirely clear that they would be merged into upstream…

LIVERPOOL MAKEFEST Makers from across the UK will descend upon Liverpool on 29 June. Liverpool MakeFest is one of the largest maker events in the UK and attracts thousands of people to Liverpool’s Central Library for a day of tech, talks and workshops. Being a maker event means that it can offer technology, arts, crafts, Daleks, rockets and much more! This is a free event, and well worth the trip to Liverpool. More details at: https://lpoolmakefest.org. GUILD OF MAKERS The Guild of Makers is a membership organisation for makers and for a yearly membership it offers a range of services, from invoicing to advice on your next professional project. The Guild started in 2018 with its first conference in Birmingham, and it returns there on 22 March. At this event…

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 I’ve just installed Ubuntu (18.10) for the first time in at least 10 years and headed straight to the software update. I can see Main, Universe, Restricted and Multiverse are all selected as default. Also, Important security updates, Recommended updates and Unsupported updates are selected as default. When considering stability and security, is it recommended to leave all of these options as default? I’m sure I remember having Universe and Multiverse de-selected, and to have ‘unsupported’ updates being installed feels a bit risky! Julian Vincent A In the past, Universe and Multiverse were not enabled by default in stock Ubuntu releases, but were in Lubuntu, Lubuntu, Xubuntu and so on, so these are well-used repositories. Distros do a great deal of testing to ensure stability and compatibility with their…

The most obvious differentiator between vector drawing packages is their more advanced graphics features, so it could be argued that any testing strategy should concentrate of these. However, a significant majority of users have little need for many of the more esoteric features; what they really need are just the basic tools for creating illustrations and diagrams for technical, scientific or business applications. This, therefore, has been our emphasis. That doesn’t mean, however, that all software is equal. While the basic drawing tools might be largely similar, products differ significantly in areas related to productivity, so our testing has also considered this aspect. This goes far beyond the design of the user interface. Included under the heading of ease-of-use, for example, is the availability of tutorials and good user documentation,…

There can be no more important features of a vector-based drawing package than the drawing tools it provides. In this paragraph we define the basic minimum, as provided by all our software. Tools are provided for drawing lines, lines with arrow heads, text, and shapes such as squares and circles, and to define the thickness and colour of the lines or outlines, and the colour of any fill. In addition to straight lines and polylines – that’s a line comprising several straight segments – freehand and curved lines are available. Editing enables objects to be moved, stretched or shrunk, and rotated. A snap feature assists in aligning objects, and the order of objects, front to back, can be defined. Several objects can be grouped so they can more easily be…

For general purpose use, we find it hard to believe that one of the packages reviewed here won’t fit the bill, but if you do want to delve a bit further, other free options – which either run under Linux or are accessed via a browser – include Dia, Method Draw, sK1 and SVG-edit. If you have a very specific application, such as creating flow diagrams, organisational diagrams and the like, there are some other programs you might like to consider. While these won’t have nearly as many features as most of the software we’ve looked at here, the features they do have are tailored to their niche applications, which makes them much easier to use. Diagramo, for example, calls itself a flowcharting program, although the samples show other types…

We’d be remiss if we didn’t mention the colossus that is MAME – the Multiple Arcade Machine Emulator. The hardware of older arcade machines could vary wildly between games, so an emulator was needed that covered all these different machines. MAME differs from other emulators in that it uses a modular approach, where individual cores are installed that power and control different machines. This approach is an effective new path that may prove to be more reliable than constantly writing new emulators with different interfaces. MAME has been around since the ’90s and is command-line driven, so you’ll want a GUI front-end for it: MESS has been on the scene for ages, but RetroArch is now the most popular. RetroArch is probably in your repository, but if not, check the…

SPECIFICATION CPU: Zilog Z80 at 3.5MHz RAM: 16/48/128K Graphics: 256x192 resolution, 8 colours Sound: CPU-driven single channel onboard speaker Storage: Cassette and ZX Microdrive OS: Sinclair BASIC Released: December 1981 Launch Price: £125 16K, £175 48K Production: 1982-1992 Worldwide sales: 5 million The Speccy. It had an awful ‘dead flesh’ keyboard, visually offensive colour-clash, and truly disgusting audio, but it was cheap – really cheap. If you were a British kid in the ’80s, this was the machine to fight for, the blue-collared hero that ushered in £2 gaming and earned Clive Sinclair a knighthood. After losing the BBC contract to Acorn, Sinclair had to fight back and did so by targeting the budget market, this time with a machine that could hold its own with videogames. Originally the ‘ZX82’…

ZX Spectrum The Fuse emulator should be in your repositories; install the fuse-emulator-gtk package, as it’s much easier to run and configure. You’ll need a system ROM to get started – our repositories had one, with spectrum-roms being the package. http://fuse-emulator.sourceforge.net Commodore 64 The best emulator is VICE, though it’s not the most user-friendly. Chances are that it will be in your repositories, but probably won’t have a ‘KERNAL’ for licensing reasons. First install your distro binaries then grab the source tarball. Open a file browser (with superuser privileges) to /usr/lib/ vice, compare these files and folders with the data folder in the source tarball, and copy any missing. http://vice-emu.sourceforge.net…

SPECIFICATION CPU: Motorola 68000 at 7.16MHz RAM: 512K (up to 8.5MB) Graphics: 4,096 colours at 320x256, 16 colours 640x512 Sound: Custom MOS Paula chip, 28KHz OS: AmigaOS 1.2 Storage: 3.5-inch floppy, optional hard disk Released: July 1985 Launch Price: £499 Production: 1987-1996 Worldwide sales: 4.85 million At first glance it appears the ST had the Amiga licked for price and power, but look more closely and the picture becomes very different. Both these machines use the 68K CPU, but the Amiga had a large colour palette and a proper multitasking GUI. More importantly, the Amiga was designed around multiple co-processors for handling audio, video and memory access – thereby freeing up the CPU and outperforming the competition. Unlike the ST, the Amiga had a great sound chip, with advanced features…

Out of all the consoles we could have covered, we chose the PlayStation because of its influence on emulator history. Initially emulators for the PlayStation were buggy, unprofessional and just too niche to worry Sony. However, two polished commercial titles would completely rock the boat and re-shape history: Connectix Virtual Game Station and bleem!. In the mid-to-late ’90s, the Macintosh was starved of games and emulators were becoming more popular. Connectix was a small company with a talent for virtualisation, which was working on a PlayStation emulat Mac, Virtual (VGS). Having library would Mac users’ gaming options, PlayStation games at full speed on a relatively iMac G3. Connectix tried to do the right thing by running it past Sony, hoping to license their BIOS and get some kind of endorsement.…

Claire Janisch is a Biomimicry Professional and co-founder of the Biomimicry for Africa Foundation. Her work involves taking inspiration from nature to solve complex problems, from engineering to material science to software development. Whether it’s buildings inspired by termite mounds, or next-generation materials based on spider silk, nature offers all kinds of creative solutions to the world’s exigencies. By studying key principles of life, such as modularity, information exchange and self-organisation, Claire helps people around the world find new and innovative approaches. Open source, it turns out, already embodies these principles, as we found out when we met her at O’Reilly’s Velocity conference in October 2018, at which she was a keynote speaker. Linux Format: For some reason, when I think of mimicking nature, the first thing that comes to…

Linda Kamau is one of Ushahidi’s longest-serving employees and its lead developer. She also developed TenFour, the check-in app. She joined Ushahidi in 2008 as a volunteer while working as a junior developer: “I was really fascinated by programming. I’d just come from school and I wanted to do something interesting and be part of something that changed the world. That was a big selling point for me. I wanted to do something that transformed lives, so that’s how I ended up working at Ushahidi,” Kamau says on a VoIP call from her offices in Kenya. Kamau took that passion for programming and co-founded AkiraChix in 2010, which provides training, mentorship and outreach programmes for women and is where she now works full time. “There were very few of us,…

I got my first Raspberry Pi back in 2012 when it seemed like the whole world was going crazy over these little devices. You couldn’t get hold of one for love nor money, but much like many others I didn’t actually know what to do with it once I did get one. For months it sat in a drawer and gathered dust. I’m pleased to say that situation changed greatly over the years, though, and most of this is down to the amazing wealth of resources and guides available via the community. That original model B is still going strong, and lives under my stairs acting as an OpenVPN gateway. I’d love to brag about how I set this up from my own vast encryption knowledge, but that would be…

First, let’s make this clear. Only work with high voltages if you know exactly what you are doing as you can be seriously injured or killed! In this tutorial we worked with higher voltages, in that we used a 9V circuit to power the fan but controlled the circuit using the 3.3V Raspberry Pi GPIO. But how did we know what to use as our switch? Well, we consulted a datasheet. Datasheets are documentation provided by a company that manufacture components. To find a datasheet for the 2n2222 NPN transistor, we used a search engine and located an appropriate document. Then with a coffee we sat down and read about the voltages and currents that our transistor could tolerate. We learnt that the emitter could be used with up to…

The DNS subsystem supports a local DNS server for the network. Queries are forwarded to upstream recursive DNS Servers. The services supports caching of standard DNS record types such as A, AAAA, CNAME and PTR. Dynamic Host Configuration Protocol (DHCP) is a network subsystem that enables a server to automatically assign an IP address to a computer from a defined scope of values configured for a given network. The DHCP implementation supports DHCPv4, DHCPv6, BOOTP and PXE protocols. The Router Advertisement subsystem provides basic autoconfiguration for IPv6 hosts. It can be used stand-alone or in conjunction with DHCPv6.…

Most people who are new to IR photography will start with the camera they already have, and we saw in the main part of this article how to check that it’s IR sensitive. Fortunately, most cameras and phones are at least partially suitable but if yours isn’t, or it doesn’t allow you to use a more aggressive IR pass filter such as a Wratten 87, it doesn’t have to cost you a fortune to find an alternative. Over the years, the hot mirror filters that block IR have become more effective so some old cameras are, in fact, much better than new ones for IR work – and the good news is that old second-hand cameras are really cheap. You’ll find online discussion groups about IR photography, and these would…

Sadly, since Ubuntu 16.04 was released, updates to SANE appear to have partially broken scanning capabilities in Ubuntu. Many scanners that worked fine in earlier versions of Ubuntu no longer work in later versions, and both our test scanners (Dell B1265dnf and Epson Perfection V370) fell into this category. The first thing to do is visit https://bugs.launchpad.net/ubuntu/+source/sane-backends/+bug/1728012 where you’ll see this problem documented in detail. If you’re lucky, as we were with the Epson V370, the workaround listed in post 25 fixed our problem: Enter the following into the empty file: Save the file, then reboot. Similar fixes have been posted here for Brother and Xerox scanners. As you can see, it appears to be an issue with both permissions and changes to file locations that necessitate the use of…

One of the great features of VirtualBox (and most other hypervisors) is the ability to use snapshots. Snapshots enable you to create a point-in-time copy of the virtual machine state. For example, prior to performing an upgrade step or change (on any VM, not just this one), taking a snapshot enables you to go back to the moment prior to the snapshot creation. It is a really valuable tool that is worth learning how to use. The snapshot management tools in VirtualBox can be found under the ‘Machine tools’ section on the right-hand side of the application. To create a point-in-time snapshot, use the Take button. To go back to that state is as simple as using the restore function. If needed, it’s possible to have a tree of snapshots…

Nextcloud’s installation is well-documented and is fairly easy to follow. However, if you’re pressed for time or aren’t well versed with the Linux CLI, Nextcloud also officially supports installation via the snap universal package format. Installing Nextcloud via snap isn’t just incredibly easy but is also very secure, since it runs in a sandboxed environment. Before you begin, make sure your Ubuntu Server installation has a static IP address. On an older Ubuntu installation, you’ll also have to install snapd with sudo apt install snapd . In any case it’s a good idea to make sure your Ubuntu installation is fully updated with the sudo apt update; sudo apt upgrade commands. When they’re done, install Nextcloud with sudo snap install nextcloud , which will fetch and install all the required…

Many of the programs that use TensorFlow are intended to recognise or qualify images, including the example in this article. TensorFlow isn’t optimised to use your hardware efficiently when analysing images, however, so to make full use of your hardware, use OpenCV. OpenCV is released under a BSD licence so is available both for free and commercial projects. It has interfaces to Python, Java and C++, making it useful for many projects. The library has been adapted to use OpenCL so it can use hardware acceleration in any popular platform. In fact, it even supports Android, so you can use your smartphone for calculations. The focus of OpenCV is on real-time applications, which is why it has been used for stitching maps, advanced robotics and interactive art. The library has…

Proposed changes to Google’s Chromium browser could spell trouble for ad blockers and other content-filtering plugins. The changes, first tabled in October 2018, centre on the Manifest v3 proposal for Chromium’s Extension platform – and thus by (arrg!–Ed) extension, Chrome and soon Microsoft Edge. Manifest files specify the permissions and resources associated with a given browser extension. The salient change is to the webRequest API, which hitherto has allowed extensions to intercept and modify, or block entirely, network requests. Should Manifest v3 in its current form go ahead, webRequest – the modus operandi for some ad blockers on Chromium – will become a read-only API. declarativeNetRequest, a new API, has been proposed; this does allow network requests to be modified, but the key difference is that the modifications are done…

“Following a great show in 2018 in A Coruña, Spain, the annual X.Org Developer’s Conference (XDC) travels across the Atlantic. Taking place at Concordia University (alma mater of yours truly) from 2-4 October 2019, this will be the first XDC to be held in Montreal, Canada. Initially conceived in 2004 at the Cambridge Research Laboratory, Massachusetts, as a meeting for people working on X Window System technologies, it has evolved over the years to become a fully fledged conference, covering all elements of the Freedesktop family, including the Mesa 3D library, X11 and Wayland protocols, as well as the Linux kernel and its DRM. The event is entirely free to attend (although registration is required), and is a great opportunity to learn about the latest developments in open source graphics.…

We try to avoid discussing vulnerabilities by referring to their logos or flashy titles, but when they reference opera-singer-fronted metal band System of a Down, we can’t help but give them a nod. The three vulnerabilities, collectively titled System Down, were found by Qualys and all lie in systemd’s journalling mechanism. Two of the vulnerabilities are memory-corruption bugs, which involve clashing the stack with an attacker-controlled memory region, and the other is an out-of-bounds read. Fedora and openSUSE compile their software with GCC’s stack-clash protection option, but otherwise the vulnerabilities have been present for at least three years. Successful exploitation of all three vulnerabilities can provide a local root shell in a matter of minutes. Fortunately, the issues are all addressed in systemd version 241, and fixes will be backported…

“I’m just back from New Zealand and I must say I’m happier than Vlad the Impaler after he discovered marshmallows. Fans of my writings will know that it was in Aotearoa that I first started using open source software full time. Oddly enough, it was my sordid involvement in the practice of Computational Group Theory that got me into all this Linux. Back then there were two programs for doing this: the proprietary Magma (http://bit.ly/lxf248magma) and the open source GAP (www.gap-system.org).Naturally, the math(s) department wasn’t willing to fork out thousands of dollars on a Magma licence, so I spent my mid-20s running lengthy computations and running various machines out of memory with GAP. If you’re interested in this stuff you should check it out. The modern way to do FOSS…

Ernesto A. Fernández posted an announcement about a new “Read-only APFS module” that provides initial Linux support for the Apple File System. APFS is a relatively new filesystem used on contemporary Mac systems, optimised for use on flash-based memory devices. Code: https://github.com/eafer/linux-apfs. Peter Xu posted a patch series titled “userfaultfd: write protection support”. These ‘uffd-wp’ patches enable applications to tightly control and monitor use of memory, such as by virtual machines. Features like QEMU’s Live Snapshot use these patches to take snapshots of the VM state without having to pause a VM in between. This will likely enable a lot of new use cases. The GNU Compiler Collection (GCC), as used to build Linux kernels and most distros with the exception of Android, is working toward its next stable release.…

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 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 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…

Anti-antivirus With the intention to switch from Windows to Linux I have been buying LXF in my local bookshop for more than a year and I have been trying many distros from the DVDs. I’ve been very surprised to never find a single article about antivirus software. Security is very important today more than ever and it is also true for Linux. Some people say that Linux does not need an antivirus, but certainly since Linux is attracting more users it will also attract more hackers. So would my Linux laptop be better off with an antivirus? Please could we have a review article and a round-up of antivirus software in a coming issue of LXF? Nestor Neil replies What a great question. I’m going to say something crazy like:…

Most of the time, Linux and its software is well-behaved, but there are times when you just want to kill a program. It may be that you started a long and resource intensive task at the wrong time, or it may be that a program has experienced an unscheduled termination (crashed) and left its window(s) on your desktop. If you started the program from a terminal, you can usually kill it with Ctrl+C, but there are other options. Sometimes a program has crashed so that it will not respond to a Ctrl+C – it needs a more brutal approach. The kill command, followed by the PID of the program, will send the equivalent of a Ctrl+C, even if the program was not run from a terminal. How you you find…

Realistically, the only reason to create a diagram or illustration is so that you can display it online or insert it into a document, so it’s essential that you can save or export it in a suitable format. Similarly, if you want to work on a drawing someone has created or, perhaps, include a third-party image in your drawing, the range of supported import formats becomes important. Nearly all the reviewed software uses a proprietary format for saving drawings, which isn’t too helpful – except in the case of LibreOffice Draw, because its native format is recognised by other LibreOffice applications. The one package that can save in a variety of formats is Inkscape, which supports SVG, compressed SVG, PostScript/EPS, Adobe Illustrator and several other vector formats. Separate from the…

Never heard of emulation? It’s when a piece of software mimics another machine in order to run its programs. For instance, you may have seen someone playing old Nintendo games on an Android phone. Emulation is best known for its use in playing old video games on modern systems, but it’s also used in many areas of computing, with many different purposes. The first emulator was developed by IBM in 1965, for the System/360 line. It could run programs written for the older 7070 system and was a hit with customers. Although emulation would continue to develop in the computing industry, it remained relatively niche until the ’90s, when game console emulation on PCs resulted in landmark court cases. Nowadays emulation is entirely mainstream and is used for everything from…

SPECIFICATION CPU: MOS Technology 6510 at 1MHz RAM: 64K Graphics: 320x200 resolution, 16 colours Sound: SID 6581 chip Storage: Cassette, 5.25-inch floppy, and ROM cartridge OS: Commodore KERNAL/Basic 2.0 Released: August 1982 Launch Price: £399 Production: 1982-1994 Worldwide sales: 17 Million Named after its 64K of RAM, the Commodore 64 was designed to be a great games machines from the outset, using custom chipsets to power functions separately from the CPU. The powerful VIC-II chip gave the Commodore 16 colours, hardware sprites, smooth scrolling and a high resolution. The SID sound chip was developed by an actual musician and wiped the floor with the competition – it’s still used by musicians today – see the box opposite for more. While many micros of the time have certain features that are…

Will Doran, Ushahidi’s senior developer, has an Msc in Machine Learning (ML), Data Modelling and Bioinformatics, so ML enhancements to the platform were inevitable.At the moment, Ushahidi has integrated two modules with the help of partner institutions. The first is CREES (https://evhart.github.io/crees), a crisis-event classification system developed with the Knowledge Media Institute at the Open University. CREES analyses text and plucks out the crisis, information and event type. It then makes suggestions, for example, ‘I think these pieces of text relate to a fire’. This is really beneficial if you’re dealing with a large deployment, says Doran. “In the Ushahidi platform you can pull from multiple data sources and get deluged with information. The idea of these tools is that they help people to divide the tasks and get to…

If you want to try your hand at thermal IR photography, add-ons for phones are now available that enable you to photograph heat. They’re expensive, but a lot cheaper than dedicated thermal IR cameras. Before buying an IR pass filter, you might like to try the cheap option of a piece of exposed, developed colour negative film, or unexposed, developed slide film, if you have any knocking about. They work as IR pass filters, but the cut-off wavelength is about 870nm, so this won’t work with all cameras. If you’re up for a challenge, the Raspberry Pi NOIR camera has no infrared blocking filter. It’s intended mostly for night time security applications but, if you’re prepared to build it into a box together with a Pi and an LCD panel,…

When you scan a photo or document, you do it at a specific resolution, measured in dpi (dots per inch). The more dots per inch in your scan, the more detailed – and larger – your image. By default, Simple Scan scans documents at 150 dpi and photos at 300 dpi, which will produce a digital image the same size as the original (typically A4 for documents, 6x4 inches for photos). This is sufficient in most cases, but there may be times when you wish to blow up a photo to a larger size – for example when scanning in smaller photos of the sort often found in family history collections. As a rule of thumb, you should be able to get away with blowing up an image to twice…

The static nature of these files means that plug-ins often wont work. For any sites that must include a comments section, it’s possible to add third-party plug-ins that provide the same facility. That local virtual machine is critical – there is no way to put the HTML back into WordPress. Therefore make sure that a copy of the virtual host is taken; should anything bad happen, restoring the original development machine becomes as easy as copying back the VM folder and reimporting it. Using this system makes security much more robust. This doesn’t absolve the administrator of good security practices, such as ensuring that the web-facing host is kept up to date, direct root login is disabled and public/private keys are being used to protect against hackers trying to brute-force…

While Nextcloud has a well-rounded yet intuitive graphical interface, it also includes a powerful command line interface (CLI) that can be used to control all aspects of the installation. Nextcloud’s CLI is a PHP script that gets its name from its origins in ownCloud and is called occ (for ownCloud Console). To use occ, move to the Nextcloud base directory (such as /var/www/nextcloud), and then run it with the web server’s owner (usually www-data or apache) in order to maintain the correct permissions on the Nextcloud files and folders. The sudo -u www-data php occ -V command fetches the version of the Nextcloud server you’re running. Using the list option such as sudo -u www-data php occ list displays all the supported commands and options. The occ equivalent of creating…

While TensorFlow has a lot of interest and is being developed very quickly, it is not alone. You can also choose between a few other frameworks, one of them being Caffe. You can use this framework when you need a deep learning network to solve your problems. The most common users are in the academic world, which is hardly surprising since it was developed at the University of California, Berkeley. Yahoo! has combined it with Spark and named it CaffeOnSpark, with the hope that it can improve searching on Flickr. Facebook has also released Caffe2 to support its own operations. The main aim of the project is to make it portable in the hope that it can run on mobile devices – which it does. The original Caffe claims to…