Linux Format的Summer 2017目录

What part of life do you wish you could virtualise? Jonni Bidwell Can we virtualise our government? And introduce our own changes and use snapshots to determine what is, and what is not, a good decision and berate those responsible accordingly. I suppose they wouldn’t let us do that, but watching virtualised leaders battle it out would make parliamentary debates more interesting. Nick Peers I don’t do nearly enough to keep fit, so perhaps being able to virtualise exercise might help me stay relatively trim without actually having to commit to doing the hard work that’s required. And I’ve never looked that good in shorts, anyway! Plus, I might be able to tweak my football ability stats to make me half-way competitive. Les Pounder Holodecks as found in Star Trek…

“Kubernetes is an open-source system that makes it possible to automate the deployment, scaling and management of containerised apps. It groups containers that make up an application into logical units for easy management and discovery. Kubernetes builds upon 15 years of experience of running production workloads at Google, combined with best-of-breed ideas and practices from the community. As one of the top four highest velocity open source projects, Kubernetes is gaining traction as the standard open source platform enabling deployments across public, private, hybrid and multi-cloud environments. This means more individuals with knowledge in Kubernetes are needed to meet the growing demand. For this reason, The Linux Foundation and Cloud Native Computing Foundation have launched a free Introduction to Kubernetes training course, LFS158x, on the edX platform. LFS158x covers some…

Liverpool Makefest A family day out with rockets and robots Now in its third year, Liverpool Makefest has become a quiet success. Taking place in Liverpool’s fantastic central library, this event sees technology meet art, music, science, special effects and cos-play. The event was organised in 2015 by husband and wife team Caroline and Mark Keep, but for 2017 the organising team was led by Jen Fenner and Mark Sabino. Both are makers in the Liverpool community, with Jen’s specialism in fine art and fashion. In previous years Makefest has seen attendee figures in the thousands and 2017 was no different: it was a packed day with something for everyone. In the Discover library we saw high-tech firing ranges using Arduino and Raspberry Pi to destroy evil aliens. In the…

I’ve been contributing to your magazine since July 2008 and still enjoy receiving each issue ever since. My main interest at present centres on SymPy and matplotliband so far I haven’t found anything in the archives in the way of PDFs or tutorials on these applications. Maybe I wasn’t looking in the right places? I also wondered whether there was any other FOSS, similar in intent to SymPy. Any information you can give me would be appreciated. Alan James, Jonni says: It’s always nice to know people are doing maths on Linux. As far as symbolic computation goes, Octave is king of the open source crop. It works as a drop-in replacement for Matlab most of the time, and can do pretty much anything it can, including having mexs (C++…

There’s no room for bleeding-edge software on a server. Veteran distros like Slackware and Debian put software through a relentless testing phase. As with software, it’s advisable to also use slightly dated and supported hardware for your production servers. Once you decide on a distro, it’s best to find hardware that the distro is certified to run on so as to avoid any surprises. Red Hat Enterprise Linux publishes a list of certified hardware. ClearOS and NethServer recommend users only use hardware from this list. This makes sense considering that these distros are based on CentOS, which is built using the RHEL codebase. ClearOS also retails the ClearBOX server with certified hardware. It’s available in multiple specs, depending on how you plan to use it, the numbers of users it’ll…

“Whether you want to set up a Windows XP VM or try out a distro, it’s easy with VirtualBox” For the casual user, no matter what operating system they may use, the easiest way to get into virtualisation is Oracle’s VirtualBox. It’s free and open source (barring some extensions that provide USB passthrough) and has a friendly and simple GUI that will enable you to set up a virtual machine in just a few clicks. Whether you want to set up a Windows XP VM to practise your hacking skills or try out a new Linux distro (from our cover disc or one that you’ve downloaded), it’s easy and intuitive with VirtualBox. Installing on Linux is just a matter of typing $ sudo apt install virtualbox or whatever is your…

Virtualisation has been around for a long time, and any old machine capable of running desktop Linux can run a guest VM. However, if you’d like that VM to carry out complex tasks smoothly, then something more modern is required. Specifically you’ll want a processor that supports virtualisation extensions, Intel VT-x or AMD-V, which are present on most 64-bit desktop CPUs since 2006. You can check for this by running egrep ‘(vmx|svm)’ / proc/cpuinfo . If the extensions aren’t there then the command won’t return anything. Note that these things can be switched off by default in the BIOS/UEFI, where they’re often named differently. So check for this - the egrep command above will still display capabilities even though they’re disabled. VMs can be a glut on memory, and both…

Not really the sort of thing you’d expect to read in Linux Format, huh? This pretty much follows the guide earlier, except you’ll need a Windows ISO, which you can download from Microsoft and use free for 30 days. In the Overview section, change BIOS for UEFI. You may need to restart libvirtd for this option to become available. In the CPUs section, we need to change the model to hostpassthrough , which probably won’t appear in the drop-down, but it can be entered manually. It’s advisable to use a VirtIO SCSI controller and use a virtual SCSI disk instead of the default virtual IDE disk, but Windows needs extra drivers before the installer will recognise this. Said drivers can be found at https://fedorapeople.org/groups/virt/virtio-win/direct-downloads/latest-virtio and the ISO mounted inside the…

Lennart Poettering recently announced a new project, Casync, which is designed to ease the burden of distributing filesystem images across the network. In an age of containers and atomically updated OSes it’s easy to see that such a tool will be handy. Casync(content-addressable synchronisation) aims to be more efficient than traditional tools (if you want, you can achieve all this with some ninja command line skills), particularly when dealing with images that are frequently updated. The project is inspired by traditional tools such as rsync, git and tar, and aims to do better than current mechanisms. Docker, for example, uses overlay2 layered filesystems, which store differences between layers. Storing these can be an unnecessary burden on the deployment system. OSTree, the git-like model that’s used for distributing/ updating filesystems as…

Another significant difference between Linux and the BSDs is the licencing. The Linux kernel, GNU-based applications, and many pieces of software originating in the Linux world are licensed under the GNU General Public License, more commonly referred to as the GPL. This license is often described as a copyleft license as opposed to copyright. It means that the GPL allows the freedom to view, distribute, and modify the source code, while demanding that all derivative works maintain the same essentials of the license. In essence, the GPL necessitates that Linux developers release the source code of their modifications. BSDs, in contrast use the BSD License which, in simple terms, permits modifications to be kept under wraps if the developer so desires. The BSD license is more permissive than the GPL…

“Smart Coloring can colourise a series of hand-drawn sketches” Image-processing application G’MIC-Qt Version: 2.0 Web: https://github.com/c-koi/gmic-qt This major release of G’MIC is much-anticipated news for those who enjoys editing images in Linux. Users of Gimp are obviously the primarily target group, because GREYC’s Magic for Image Computing has now been tightly integrated with this famous bitmap editor. G’MIC is a fully featured, open-source framework for processing your images, including converting, applying filters, manipulating bitmap datasets and more. Along with the gmic_gimp plugin, the project provides the command line gmic executable (which works similarly to the ImageMagick suite), a C++ library called libgmic, and a few other tools. Version 2.0 G’MIChas since moved to Qt5, although it’s still bound to Gimp and can be found under the Filters menu of the…

My days are spent growing eyes in the lab to study child blindness. But I have big dreams and am always thinking of the next thing that would change the world for the better. I noticed that there’s a huge lack of cross-disciplinary research, so I thought, “Why don’t I bridge the gap between arts, science and tech?” That’s why I decided to learn coding and robotics. My adventures with the Raspberry Pi begin with the launch of the Pi Zero W. In the same week, I successfully confused The Pi Hut with modmypi and Pimoroni on Twitter, and I attended the Raspberry Pi fifth birthday in Cambridge! My confusion led to my first friendship from the Raspberry Pi community. It’s been incredibly easy to learn from Pi enthusiasts by…

Our expert Les Pounder Les is a freelance hacker and maker who loves playing with tech. He support the Raspberry Pi Foundation’s Picademy scheme as a trainer and blogs at http:// www.bigl.es. In this tutorial we’ll explore Node-RED, a powerful visual language that connects flows of “nodes” to create code. We’ll build a Twitter alarm system that alerts us to tweets matching a certain hashtag. When a tweet is received an LED will light up, then the tweet is saved to a file for storage. The tweet is then read to the user using text-to-speech. If we’re away from our desk, an email is sent to alert us. Our hardware build for this project is a solitary LED connected to GPIO21, and to GND via the 330 ohm resistor. Please…

Why display banners on-screen when you can get your computer to read it back to you? eSpeak (https://espeak.sourceforget.net) is a tiny speech synthesiser tool that you can install from the main repos ( sudo apt-get install espeak ). The basic syntax is this: Too quiet? Use the -a flag to alter the volume from 0 to 200 (the default is 100). You can adjust the voice’s pitch using the -p flag (0-99, default 50), and speed things up using -s (measured in words per minute, 175 is the default, with a lower limit of 80 and no upper limit, but around 260 is a good one to aim for). The system default voice is selected by default, but you can change this. First, type espeak --voices to see what’s available,…

Sign up for any Linux Foundation training course today and enjoy a 10* per cent discount off the normal price! The experts at the Linux Foundation have created courses that span the entire range of Linux, from classic Sysadmin courses to emerging technologies such as OpenStack and Open Daylight. If you’ve enjoyed this small sample and want to learn more, we’ve take this segment from the highly popular LFS201 Essentials of System Administration course, that comes with the optional Linux Foundation Certified Sysadmin qualification. The course is entirely online, is self-paced and contains over 80 expert labs with solutions for you to practise your new skills. To claim your 10 per cent discount on ANY course follow these steps: Go to https://training.linuxfoundation.org/linux-courses and browse the complete range of courses. Select the…

While Rescatuxwill save your day more often than not, it does have its limitations. If you’ve run through this tutorial and used the relevant Rescapp option, but are still unable to recover from the failure, then it’s time to defer to the wisdom of the elders. Rescatuxis a ferocious scribbler and creates a logfile for virtually all tasks. The Support section at the top of the Rescapp utility lists the various options that comes in handy when you’re unable to troubleshoot an issue yourself. The Show log options opens the folder that houses all the logs that you can peruse through to figure out the exact reason for a task’s failure. If you’re unable to figure out the solution, you can use the Share log option to copy the contents…

LUKS containers don’t make any attempt to conceal their nature, so if you encrypt a drive this way, it’s obvious you’ve something to hide. Fortunately you can use Cryptsetupin plain mode, which contains no giveaway volume headers. To anyone examining the drive, it’ll simply appear to be full of random data. To get started locate your chosen partition or insert a USB stick, open Terminal and wipe the drive with dd . For example, sudo dd if=/dev/ urandom of=/dev/sdb1 bs=1M . The basic command for using Cryptsetupin plain mode is cryptsetup <options> open --type plain <device> <name> . Take some time to read through the Cryptsetupmain page to see which options are right for you, for instance: This command must be entered in exactly the same way each time you…

While technically you can manually timestamp a file yourself, it’s far quicker and easier to make use of (https://opentimestamps.org) OpenTimeStamps. To get started visit the website and drag the file you wish to stamp into the field named Data to Timestamp, then click Stamp. The website will generate a file with the extension .ots. Save this file to your hard drive. You can verify it at any time by visiting the website again and dragging it into the section marked TimeStamped Data. The website recommends using the opentimestamps-client to verify files, as this is more secure. To get started open Terminal and run git clone https://github.com/opentimestamps/ opentimestamps-client , then change to the directory with cd opentimestamps-client . Install the necessary dependencies by running sudo apt-get install python3-pip then sudo pip3…

Our expert Mihalis Tsoukalos is a UNIX administrator, a programmer, a DBA and a mathematician who enjoys writing articles and learning new things. He is currently writing a book called Go Systems Programming. You can reach him at www.mtsoukalos.eu and @mactsouk. ZFS is a 128-bit file system that can handle zettabytes of data – one zettabyte is equal to one million terabytes! ZFS was designed by Sun Microsystems to be a filesystem that offers protection against data loss and support for extremely large partitions and was originally a proprietary project. However, this changed in 2005 when ZFS became open source software. We’re going to look at how to add a ZFS partition to an existing Linux system that uses ext4 for the root (/) file system, how to delete ZFS…

This tutorial presented the most functional ZFS features along with their administrative commands, but ZFS can do many more things. First of all, ZFS uses checksums behind the scenes to ensure data integrity. You can use one of the following fletcher2, fletcher4 and sha256 checksum algorithms. Although checksums can be disabled, this isn’t recommended because this is a practical feature that protects your data. Additionally, ZFS supports data compression, which is turned off by default. Although compression might slow down the performance of a ZFS filesystem, there are times that you might see an increase on read and write throughput because with compression, fewer blocks are accessed for writing or reading the same data. However, if you have lots of disk space then you might not have any need for…

If you’re going to use pi all the time in a program, or if your program requires a large number of digits, then employing the fastest method is critical. However, even if your method of choice is slow, it might be able to do your job when you’re not after a high degree of accuracy. The main reason for rejecting a particular technique or algorithm is when it can’t give you the kind of accuracy you want – this happens because there’s no substitute for accuracy. Additionally, you might not consider a technique when it gives you pi as a string whereas you want to use it as a number for carrying out further calculations. Finally, if speed is the main concern for you, then saving pi into a file…

Each Linux file has permissions associated with it. Look at the following output: The first column of the previous output of the lscommand shows the permissions of each file. As you can see, the permissions of each file take 10 places, which can also be viewed as bits. Apart from the first bit, which is defined by Linux and declares the type of the entry, the remaining nine places can be collected into three groups with each one having three bits. The first set explains the permissions of the user, the second set is about the permissions of the main Linux group the user belongs to, and the last part is about the permissions of the rest of the users. If you’re familiar with binary arithmetic, it’s easy to understand…

Our DVDs usually contain three or four distros, although we’ve managed to squeeze six separate distros on a single DVD with the application of a large hammer! Historically, four was the norm, but usually we only have room for three distros these day. This month we’re down to two. There can be two reasons for the increase in size of distros. The software they contain – and this includes the desktop applications as well as the core OS – could be getting bigger. Or we could be getting more of them. So is free software getting bigger, or is there more of it? As is usually the case with questions of this type, the answer lies somewhere in between. There’s a lot more free software out there, but it’s also…

Ubuntu Phone post-mortem We take a look into just what went wrong with the Ubuntu Phone and Canonical’s failed convergence. The Linux Multimedia Studio It’s (really) time we made beautiful music together with the pro-level music creation suite known as LMMS. Open source phone dream As one dream dies, many more spring up from the fertile soil the dying body of another leaves behind. Sync, sync, baby We Roundupthe best file synchronisation tools so you can keep your files in, erm, sync wherever you are. Contents of future issues subject to change – our brains may have exploded with all the knowledge!…

We expect virtualisation isn’t anything new to you, our happy reader, but it’s a topic that’s constantly evolving, improving and has become essential to a world that expects the ability to spin up multiple instances remotely in seconds. So this issue we’re holding your hand and taking you through the vital basics of creating a VirtualBox, getting more from managed snapshots to newer Docker Containers and cutting-edge development of GPU passthrough. So by the end of this issue you should feel you know your KVMs from your kernel chroots. Even if you’re just using VirtualBox to keep a sneaky install of Windows hidden away (admit it, you know it’s true), the copious amounts of storage and computing power that even a modest PC offers can happily cope with storing and…

Linux’s advancement into almost every aspect of our lives continues with the news that Toyota will be including an Automotive Grade Linux (AGL)-based (see Interview LXF218) infotainment system to its 2018 Camry model, making it the first car in the US market to do so. AGL is an open source platform based on Linux, and it’ll be used as a platform for Toyota’s Entune 3.0 system. With the increase in car manufacturers producing connected ‘smart cars’, there was a concern that it would give rise to a deluge of proprietary and incompatible systems, which is something AGL has been designed for to avoid. AGL is supported by the Linux Foundation and has a membership of over 100 of the most important names in the auto and tech industries. AGL will…

SHARKLINUX 2017.07 SharkLinux, an Ubuntu-based distro featuring the MATE desktop, and automatically upgrades packages to keep them secure, has a new version out. This new build includes improved hardware support through Ubuntu’s Hardware Enablement (HWE) kernel, and LibreOffice no longer installs the full suite, instead using a slimmer default install. Offline installs are no longer required, which means the install media will no longer disable internet connectivity on a device when the installation process begins. Go to http://sharklinuxos.org/documents/current-release for more information about the SharkLinux release announcement. PROXMOX VIRTUAL ENVIRONMENT 5.0 A new version of the Debian-based distro that specialises in running containers and virtual appliances has been released. This new version is based on Debian 9 Stretch and contains the Linux kernel 4.10. The distro includes a new Proxmox VE…

PyCon UK 2017 Back for another year in Cardiff between October 26 and 30, PyCon UK is a celebration of everything Python. Along with the many talks, workshops and panel discussions covering the breadth of Python, we see the return of the popular education track, supported by the Raspberry Pi Foundation. The education track is open to teachers and educators and is there to help them use Python in the classroom. There will also be a special Raspberry Jam on the Saturday for families to attend. http://2017.pyconuk.org Barents Raspberry Jam The most northern Raspberry Jam has just been announced. This is the first jam for the organisers, so for those eager Raspberry Pi makers in Norway this is your chance to show off your project, and meet others who like…

The choice of a server distribution depends entirely on the intended use. If all you need is a limited or a specific function server, such as to protect your privacy by hiding behind a proxy, or running a firewall to protect yourself, it makes little sense to adopt a multi-purpose server distribution. While you can configure iptables on most Linux distros, specialist distros such as IPFire are quite easy to roll out and configure. If you need more features such as spam filtering, bandwidth control, virus blocker, and such, you can try Untangle. Apart from the ever popular Red Hat Enterprise Linux and its host of community supported derivatives, Ubuntu and Fedora too have launched themselves into the server domain and their respective server editions can be viable options if…

So our VM is up and running, but you might notice it’s running a little sluggishly. If you didn’t notice that, try playing a YouTube video. We can fix this, to some extent anyway, by installing the VirtualBox Guest Additions inside the VM. Many distributions such as Ubuntu include these by default, but Debian isn’t one of them, so we must compile these by hand. Don’t worry, it’s not hard. First (in the VM) install the compiler gubbins and module tools with: $ sudo apt-get install build-essential module-assistant dkms Now from the menu bar in the VM’s window, choose Devices>Insert Guest Additions CD Image. You’ll be prompted to download the disc image, do this (it’s about 60MB). Next, insert this into the virtual drive, which you should do. The disc…

“VFIO enables PCI devices to be remapped and reset from within the Linux kernel” Linux gaming has come a long way in a relatively short time. This is due to various factors: a flourishing indie games scene, major game engines supporting Linux, Valve and their SteamOS play, improvements to display drivers, and porting work from the likes of Feral and Virtual Programming. That notwithstanding, there are titles that will never come to Linux and those that do generally perform worse there. Serious gamers will, in some situations, be forced to resort to Redmond’s OS, and this is unfortunate. It’s long been possible to run Windows in a virtual machine, but even with fast hardware this doesn’t work very well. Virtualbox’s 3D acceleration doesn’t really do anything for DirectX 10, 11…

WORKING WITH BUSINESS IN MIND “You need to make sure that you design an OS that’s fit for purpose” Mike Bell is executive vice-president at Canonical’s Devices and IoT division. Earlier in 2017 we talked to Mike (back in LXF223) about some of what Canonical exhibited at Mobile World Congress 2017, and didn’t have space to print everything. Now we’ve made room with updates… Mike shares his valuable insights about Snaps, Canonical’s secure and distro-agnostic packaging format, and Ubuntu Core, the slimline Linux designed for IoT. Since MWC2017, there have been some changes at Canonical - obviously, some readers will still be sore about Unity being shuttered, but some exciting new partnerships have been made in the area of Edge Computing, where data is processed near where it’s collected/generated, rather…

FreeBSD is the most used of the BSDs according to the BSD usage survey report. The OS had its first release back in 1993 and its popularity has spawned several derivatives. TrueOS (formerly PC-BSD) is one such descendent that’s made a name for itself by extending FreeBSD’s famed stability to everyday desktop users. OpenBSD is seen as one of the safest operating systems. Thanks to its rigorous code audit and security-first development model, it’s a popular option for security-conscious deployments such as firewalls, intrusion detection systems, and general purpose servers. It’s designed for specialised usage so OpenBSD’s hardware supports focuses more on Enterprise-grade hardware and even virtual hardware. True to its tagline which reads “Of course it runs NetBSD”, the BSD distro that’s been around since the early 90s is…

Node-RED is a browser-based editor that uses nodes to connected into a flow, to link the online world with the physical, commonly referred to as IoT (Internet of Things). Editing the flow is a matter of connecting the nodes. Each node has grey dots. Some are on the left, and these are output nodes such as publishing data to the debug console. Some nodes have grey dots on the right - these are input nodes such as subscribing to data via mqtt. Some nodes have the grey dots on both sides, such as delays that can be used to slow down the flow. Other nodes can be edited to provide enhanced functionality, such as the function node, which is used to write custom functions in JavaScript. This node can also…

The ultimate trick with ASCII art is to use it to watch video, and that’s made possible by a combination of the application mplayer ( sudo apt-get install mplayer ) and libaa-bin(see main text) for monochrome renderings and libcaca (installed alongside mplayer) for colour ones. Assuming your video lives in your /Videos folder, use the following command, substituting /Videos/ file.mp4 with the path and name of your file: During playback, you can alter contrast using the 1 and 2 keys, while pressing 3 and 4 does the same with brightness. Press 5 to toggle fast rendering on and off, and 6 to switch dithering mode between none, error distribution and Floyd Steinberg. Finally press 7 to invert the image. Pause playback with the spacebar and press Enter to stop. If…

Our expert Mayank Sharma is a technical author and former contributing editor at Linux.com, but now spends his time playing Linux games all day in his underpants. So many things can mess up your computer. A careless keypress can delete a file, rewrite the bootloader, mess up the login password or cause other dreaded issues. If you find yourself in a similar situation, stop panicking and grab a hold of the Rescatux (www.supergrubdisk.org/ rescatux) distribution. The Live CD offers a rich collection of tools that you can use to address a wide range of problems in your Linux installation. Moreover, Rescatux also comes in handy if you dual-boot and can fix several common issues with the Windows partitions as well. The distribution bundles all the important and useful tools to fix…

One of the oldest and simplest ways to colour Bitcoins, known as EPOBC, is to alter the nSequence field when sending Bitcoin transactions (normally it’s unused). Because this doesn’t affect the size of the transactions, sending coloured coins in this way is no more expensive than sending regular coloured coins. However, nSequence is only a 32-bit integer, which doesn’t allow for sending large amounts of metadata about your chosen asset. You also need to pay a certain minimum amount of Bitcoins for each transaction. The OpenAssets Protocol (https://github.com/OpenAssets/open-assets-protocol), used by CoinPrism, seeks to improve on EPOBC by modifying the Bitcoin Script opcode OP_ RETURN. Metadata is stored in the Blockchain and can link to elsewhere on the web, such as to CoinPrism’s servers. The Colu Colored Coins (http://colu.co) implementation also…

Generally speaking, the more RAM you have installed in your computer and the faster its processor is, the better the performance of ZFS will be, which is indeed true for almost everything that’s computer related! However, as a rule of thumb, you’ll need about 1GB of RAM for each terabyte of storage that you have and you should start with a Linux system that has at least 4GB of ECC RAM. Additionally, you’re advised to use fast hard disk drives. Finally, you’ll need at least three physical hard disk drives in order to create a RAID 5 ZFS partition. However, if you just want to test ZFS, you can use a Virtual Machine and create as many virtual drives as needed for your testing purposes. Please remember that you should…

Our expert Mihalis Tsoukalos is a UNIX administrator, a programmer, a DBA and a mathematician who enjoys writing articles and learning new things. This issue’s challenge is to calculate Pi without using a library or a module. Although the problem looks easy, you might find it more interesting when you realise that you have to calculate Pi with a specified degree of accuracy. This means that using a simple calculation isn’t enough: you’ll need a method that’s both fast and precise. The real benefit of dealing with programming puzzles is that you pick up interesting bits of knowledge along the way. So for example, in this tutorial you’ll learn Go, Perl, Python 3 and C concepts as well as how to typeset complex equations in LaTeX. Fun times lie ahead!…

Here, I’ll be showing how to implement the cp command line utility in Python 3 – and our Python version will be called pycp.py. All operating systems offer at least one way to copy files and Linux is no exception. To understand how essential the cpcommand is, you should know that it is located inside /bin, which is available even if you boot your Linux machine in single user mode. Using cp The following output shows various uses of the cp utility: The first command copies the cpexecutable into the current directory – as you can see, the new file belongs to the current user, whereas the original file belongs to the root user. The last cpcommand illustrates the use of the -i option of cp. You can check the…

Many open source projects have evocative, amusing and iconic mascots – including the beloved Tux the penguin, the mascot of the Linux kernel. Now LibreOffice is keen to get a mascot. The plain white document icon that it’s associated with (and which will remain) is a minimalist and concise representation of the software, but it doesn’t inspire much affection. So LibreOffice is running a competition to design its mascot – with the winner receiving a Slimbook Katana ultrabook, as well as having their design immortalised. find out more at http://bit.ly/LXF227libre contest ends 31 August! Let’s Encrypt, the free and open automated certificate authority, has reached a new milestone, with over 100 million certificates issued. This is certainly an impressive number, and bodes well for Let’s Encrypt’s worthy goal of a…

“Last June, Debian 9 was released. One of the oldest Linux distributions around (almost 24 years), Debian is still purely community driven and has tallied some impressive numbers over the years: over 1,000 developers, over 25,000 source packages and 10 different hardware architectures officially supported. However, one aspect I really enjoy is its flexibility to be moulded into so many different shapes and sizes. At Collabora, not only do we run our servers on Debian, we also use it in a range of projects, from the smallest embedded systems to laptops and desktops. Debian keeps a Derivative Census on its wiki, which provides an interesting grab bag of things that have been done using Debian as a baseline, some of which Collabora has even helped start. There are the usual…

Linux? Due to terribly slow performance of Windows 10 I’m strongly considering Linux. Will installed Windows programs run in Linux? What else do I need to know? Bob Beyerlein, via email Neil says: The easy answer is no, installed Windows apps won’t run on Linux. Linux would run/install as its own OS either beside Windows 10 or as a replacement. You’re able to run many standard Windows EXE using a system called WINE, but this doesn’t extend to the new Windows Store Apps. Though frankly I’d advise you to seek out open source replacements where you can - they’ll be more stable, faster and respect your freedom as a user. If you want to get started see LXF226 for our ‘Install Linux’ in-depth guide. C the Answers Where is the…

A familiarity with Linux internals and mastery of networking may be all that you need to install a server, but an installed distro does not a server make. Even a seasoned operator needs a little help getting all the services to play nice together. This is why documentation is an important factor in choosing a server distro. All the distros on test provide similar set of aids for users. Each hosts forum boards that serve as comprehensive repositories on configuration tips for various services and best security practices. Even a small amount of time spent on the forums would reveal the pitfalls to avoid. There’s also the wiki-hosted tutorials and how-tos, and user and administrator guides. For its community edition, Univention provides forums and a host of detailed tutorials and…

“However you use Linux, the chances are there’s something to be gained from virtualisation” Running an operating system on real hardware is so passé. All those hours making sure your hardware is set up and behaving correctly, gently massaging each component’s quirks away with udev rules, modprobe options and demon-exorcising incantations. Yawn. Then so many more hours installing and configuring all the required software so that everything’s just right. It can seem like an awful lot of effort just to, say, try out a Linux distribution. And it can also present you with a whole lot of extra work if something goes wrong and it wipes out your everyday Linux install (this should never happen, but never say never). In an enterprise scenario, one also needs to figure out a…

Virtual what? What does hardware virtualisation do? The AMD-V and VT-x systems added virtual MMU modes to greatly speed memory operations, later specific instructions to trick guests into thinking they’re on native hardware and more recently virtual I/O modes for peripherals via AMD-Vi and VT-d. We’ve just seen that VirtualBox is easy to get to grips with. It’s cross platform, which makes it handy for people familiar with other OSes. It’s also open source, including (since 2010) the Guest additions. The fact that it’s made by Oracle gives some people the heebie-jeebies though, and we know that many of our readers prefer to do things at the command line. QEMU (Quick Emulator) isn’t just a hypervisor (see later), but also a machine and processor emulator, and we’re going to be…

For this trickery to work some vaguely modern hardware is required, and even with modern hardware you may run into issues. The graphics card used by the host can be anything, even integrated graphics. If you have two discrete GPUs, then you’ll want to be familiar with the key combination for entering the BIOS/UEFI as, due to Murphy’s law, your machine will try and boot from the wrong graphics card. The guest’s graphics card will need to support UEFI (the motherboard needn’t) since we’re booting with OVMF. It’s possible that an updated GPU BIOS is available from the manufacturer (some people have reported success by just asking them), which you can pass to QEMU via the -romfile option, rather than flashing your graphics card. Generally, anything manufactured after 2012 will…

Towards the end of the last decade there was an industry-wide trend towards virtualising everything. People realised that there were potential savings to be made by stuffing a machine full of VMs, rather than the traditional “one server, one task” approach. This is to some extent reasonable: a mail server might spend a lot of its time idle, so maybe there’s enough spare resources to run some kind of database backend on the same machine? However, running both services on the same OS is risky since a failure of one service could bring down the whole system, or maybe we can’t trust the OS to handle the resource contention, should both services become simultaneously very busy. So we virtualise both services and thanks to hardware advances neither suffers any tangible…

There are many open source as well as commercial products based on BSD, due to its technical prowess and permissive licensing. Popular open source products include NAS distros like FreeNAS and NAS4Free and firewall projects such as the embedded m0n0wall distro and its fork for regular computers, pfsense. Then there’s the open source Darwin project by Apple, which produces the core components upon which the company’s proprietary OSes, OS X and iOS, are based. Darwin uses code that’s derived from BSD, which is also used as the basis for the file systems and networking facilities of OS X. There are other commercial products based on BSD by multinational hardware and software companies, such as Dell’s iSCSI SAN arrays. Silicon Graphics International also uses FreeBSD in their ArcFiniti MAID (standing for…

Our expert Stuart Burns works as a systems admin for a Fortune 500 company. He specialises in non-Wintel platforms and in his spare time often tinkers with anything technology related. Since the original Raspberry Pi arrived there have been many changes from the original, including more cores, more functionality and more RAM. All these features are good, but the Raspberry Pi foundation is going back to minimalism with the new Pi Zero W. The Zero W is all about mobile computing in a tiny package with built-in wireless networking (hence the W monicker) and for a bargain price at around £11. While the Zero W may not be as powerful as the new Pi 3, its performance is good enough for tinkering, thus staying true to the original Raspberry Pi…

Our expert Nick Peers has enjoyed playing with ASCII art and generally getting up to silliness with the Terminal’s help this month. It makes a pleasant change from the norm. So far in our ongoing series examining the Terminal we’ve focused on the practical side of things. But there’s more to life than being sensible, so with this in mind, let’s go on a tour of some of the more frivolous commands and tools you can add to your repertoire. Have fun with mistypes Ever accidentally typed sl instead of ls ? You’d expect a Command not found error, but Ubuntu will prompt you to install the cryptic sltool instead. The sl stands for Steam Locomotive, so instead of being told about the tool you next time you mistype ls…

Our expert Jonni Bidwell isn’t very good at time keeping. But that’s okay, we have cron jobs that can do that. Too bad he doesn’t understand the syntax. Linux systems are capable of using a variety of filesystems. This is accomplished through the Virtual File System (VFS) abstraction layer that stands between the software and the on-disk filesystem. Advanced journalling filesystems have become standard in enterprise distributions. Applications read and write files, rather than dealing with physical locations on the hardware where files are stored. Files and their names are an abstraction camouflaging the physical I/O layer. Directly writing to disk, ignoring the filesystem layer, is dangerous and is only done by low-level operating system software, never by a user program. Local filesystems live within a disk partition, which can…

Many problems with the Grub2 bootloader can be resolved with the touch of a button thanks to Boot-Repair. The program has an intuitive user interface, it can scan and comprehend various disk layouts and partitioning schemes, and can sniff out and correctly identify operating system installations inside them. The utility works on both traditional computers with MBR as well as the newer UEFI computers with the GPT layout. Boot-Repairis available under the Expert Tools category in the Rescapp utility. When you launch it, the app will scan your hard disk before displaying you its simple interface. Most users can easily follow the tool’s advice and simply press the Recommended repair button, which should fix most broken bootloader. After it’s restored your bootloader, the tool also spits out a small URL…

Our expert Nate Drake Nate is a freelance technology journalist specialising in cybersecurity and retro tech. He uses LUKS to hide his copy of Captain Kidd’s treasure map. Any grizzled yet privacy-conscious Ubuntu users may remember that back in the day, keeping your data safe was far from easy. The steps involved either supreme mastery of the command line or using an alternate installation CD to encrypt your Ubuntu installation. Things have changed. When you insert a DVD of Ubuntu and its variants, the graphical installer now offers you the option to encrypt your system using LVM (Logical Volume Manager), which manages disk drives on LUKS (Linux Unified Key Setup), the standard for Linux Hard Drive encryption. For most users this is a great way to save time, protect your…

Our expert Nate Drake After creating a pizza-based currency, Nate amused no one but himself by offering friends a “pizza the action”, claiming that he “kneaded the dough.” In May 2016, an Australian named Craig Wright claimed to be Satoshi Nakamoto, the elusive creator of the Bitcoin. One of his key claims was that he could link his identity to one of the very first Bitcoin transactions ever sent. Bitcoin transactions are managed by a Blockchain – a blob of data that exists across thousands of servers around the world. Each Bitcoin user has a private key used to sign outgoing transactions, as well as a public Bitcoin address that they can share with others to receive payments. In most cases, people use wallet software to automatically generate these addresses,…

RAID stands for Redundant Array of Independent Disks and is a technique that enables you to store your data on multiple hard disks, in order to protect your data when one or more hard disks fail. There are many RAID configurations including RAID 0, RAID 1, RAID 5, RAID 6 and RAID 10, which is known as RAID 1+0. RAID 0 offers no redundancy because it just makes it possible for you to treat many disks as one, which increases the performance of most operations because most take place across multiple disks in parallel. However, if one of the disks fails then you’ll most likely lose all of your data. As a result RAID 0 should never be used for storing critical data. In RAID 1 each pair of disk…

So, the code challenge of this issue is to calculate pi with the desired number of digits, which means that the technique you decide to use should not have a limit in the number of digits that it can compute. One thing that you should definitely consider is whether your programming language of choice supports floating point numbers with a large number of digits. This is because you might be asked to calculate pi with 1,000 or even 1,000,000 digits, which as you can imagine is no walk in the park. As an example, C has no support for very large floating point numbers, unless you want to search for an external library that implements its own datatype that is suitable for the task. The list of techniques that enable…

The strace utility enables you to see what happens behind the scenes when you execute a program or a script. Strictly speaking, strace traces the system calls and signals of an executable program and displays them on your screen. Using strace against pycp.py displays the following type of information: The aforementioned output reveals that your pycp.py script is executed as C functions and C system calls because this is the only way to communicate with the Linux kernel. Nevertheless, writing the same program in C would have required many more lines of code and many more hours of debugging.…