Indholdsfortegnelse for No. 168 i Linux User & Developer

This issue » Multi boot your system » Master virtualisation » 10 best boards for makers » Run Linux on an Android device Welcome to the latest issue of Linux User & Developer, the UK and America’s favourite Linux and open source magazine. Wouldn’t it be nice to be able to run every operating system or distro you fancied? The trouble is, affording the hardware to do so might be a bit of a problem – unless, of course, you multi boot your machine. Partitioning your hard drive allows you to run two or more distros or operating systems on one computer. Each one gets to take full advantage of the system’s resources, and you can flip in and out of them with the flick of a restart switch. In…

One operating system doesn’t always cut it, especially when a computer is used professionally. Some applications are available only for Red Hat, while other developers choose to support only Ubuntu. In addition to that, CAD, EDA and the infamous Visual Studio product families are available for Windows only – let’s not even get started on games. Installing all of these operating systems on one workstation is both cost- and space-effective: having to purchase motherboard, RAM, CPU and GPU multiple times tends to add up quite quickly. Furthermore, simply adding a few hard drives is not a problem with most workstations – this text was written on a 16GB RAM octacore AMD behemoth hosting five HDDs. However, having access to multiple hard drives is not necessary for multi-boot systems. This guide…

After power-up, the BIOS of the workstation performs a quick self-test and passes control to a special bit of code called a bootloader. This is what is responsible for passing execution to one or more operating system ByteStreams that actually bring the station up. While Linux initially started via a bootloader called LILO, the GNU Project’s GRUB has since become the standard for most distributions. It was initially intended to boot GNU’s Hurd operating system – while that platform competes with Duke Nukem for the vapourware throne, components of it have since been reused in various other Unix operating systems. Why GRUB? GRUB compares favourably to LILO for a variety of reasons. First of all, the loader is not limited to residing in the traditional MBR – in fact, it…

The following tutorial assumes that a newly commissioned single-disk workstation is to be populated with a variety of operating systems. Our first candidate is a preview version of Windows 10, which can be downloaded from the Windows Insider program (https://insider.windows.com/) after signing up and agreeing to the terms and conditions. Next, proceed to burn it onto a DVD or an USB stick. Finally, insert it into your workstation and set it as the start-up medium. 01 Set up language and more Windows 10’s setup process starts out by asking you to specify the language and keyboard settings: this is important as it makes sure that the keyboard behaves correctly during the setup process. Next, click “Install Now” to start the actual deployment process. At the current stage of the proceedings,…

Ubuntu is a great everyday operating system. It’s often the default distro used for introducing new users to Linux. Many development and enterprise products have started supporting Ubuntu recently, making it a great overall distro, and it can be installed with minimal effort. Linux installs are at somewhat less risk from ransomware than Windows (simply because malware authors tend to focus their efforts on large userbases running homogenous code), so performing regular tasks (browsing, social media etc) on an everyday Linux distro can help add a thin but useful extra layer of security. 01 Get started Just like Windows, Ubuntu comes in the form of an ISO file, which must be burnt onto an USB stick or a DVD (it’s also on this issue’s disc and FileSilo). Keeping this installation…

One of the disadvantages of open operating systems is the emergence of multiple solutions for one problem: for example, CentOS and Ubuntu use widely varying bootloaders. If a Windows machine forces an update (hello, Windows 10) that you hadn’t planned for, this can sometimes hide your bootloader at startup, although fortunately it doesn’t delete the data itself. Happily, restoring the venerable GRUB is not particularly difficult if you have not overwritten the actual partitions. 01 Fire up Ubuntu The aforementioned USB stick or this issue’s disc containing Ubuntu’s installation media comes in really handy at this point – ram it into your workstation and boot from it. Next, select the option “Try Ubuntu” when prompted. After a few seconds, make yourself at home in a version of the Ubuntu desktop…

Resources SuperSU bit.ly/1fpnTbt Root Checker bit.ly/192fWqN Complete Linux Installer bit.ly/292jnRw Linux Deploy bit.ly/297WGh4 Ubuntu Touch wiki.ubuntu.com/Touch/Devices Why would you want to run full Linux on your Android device? That’s the question we’re often asked when we mention that we have a full Debian install accessible on our phone. Actually, it’s more useful than most might think (although, as a Linux user, you know better anyway!). Being able to run up a full LAMP stack is handy, we can get quick and easy access to all our favourite Linux tools and even use the Linux build as an option for syncing content to and from the device with good old rsync. In order to be able to run Linux in a chroot environment on your Android device, there are a couple…

Resources A text editor such as Emacs or vi The Go compiler This tutorial will talk about creating and using Go packages. Packages offer a very convenient way of grouping related functions and variables and using them as a set instead of individual components. Other programming languages call packages modules or libraries. The main purpose of packages is to make the design and implementation of software easier to understand and maintain. Pay special attention to this tutorial because sooner rather than later you will need to create and distribute your own Go packages. Additionally, make sure that you thoroughly understand the part that talks about Go environment variables, because using them correctly will make your life easier. The next tutorial is the Go series will talk about File I/O in…

£13/$17 • Microbit.co.uk After delays with the production of the Micro:bit, the BBC’s pocket-sized microcomputer was finally made available in 2016. Although it was initially handed out to every Year 7 schoolchild in the UK as an educational tool, it’s now one of the more sought-after computers out there. While its design may look a little different from many of the boards featured here, it’s similar in functionality. There’s built-in Bluetooth, five sensor ports and power comes from two AAA batteries. One of the key reasons behind the Micro:bit’s popularity is its web-based editing environment, which allows for budding programmers to seamlessly switch between different programming languages – something that many leading boards lack. The 32-bit ARM processor does perhaps lack the firepower that the Pi offers, but in terms…

Wood does not affect the gesture detection of the Skywriter HAT Where did the idea for the remote control stem from? When I come across interesting parts online, I tend to buy them, even if I don’t have a specific project in mind yet. That was the case with Pimoroni’s Skywriter HAT. I knew I’d be using it in a project at some point in time, but didn’t know what at the time. Later on, my children were asking to see a certain show. My daughter, five years old, started swiping on the tablet looking for the show. It was a TV show, however, and wasn’t available on the tablet. Using the remotes was too difficult for her: you have to turn on the TV, then the decoder using a…

What you’ll need An old/new toy Resistors Small disc motor LED A radio Small webcam Female-to-female jumper jerky wire Combining an old toy and a Raspberry Pi, you can embed a selection of components to create your own augmented toy that responds to user input. For example, take a £3 R2-D2 sweet dispenser, light it up, play music and stream a live web feed to your mobile device. Part one of this two-part tutorial covers setting up four basic features: an LED for the eye, a haptic motor to simulate an electric shock, a webcam stream from a hidden camera and the Star Wars theme tune broadcast to a radio. You may choose to combine these with your own hacks or use them as standalone features in other projects. Don’t…

etcd is a “distributed, consistent key-value store for shared configuration and service discovery,” whose stored data is automatically distributed and replicated. The Raft consensus algorithm, which is very efficient for small clusters, provides automated master election and consensus establishment. The new release’s API brings improved scalability, thanks to a new storage engine, and supports Multi-Version Concurrency Control (MVCC). Installation for most will be a matter of unpacking the pre-built binary and running it – or following the Docker instructions. etcd is written in Go – the language that seems, ironically, to be designed to be difficult to Google for – and is rigorously tested, as well as proven in some very large scale deployments. The included etcdctl is a command line interface for exploring your cluster or running scripts, but…

Welcome to the Linux User & Developer DVD. This issue we’ll help you multi boot your machine. Whether you want to combine Windows and Linux or several distros, we’ve got everything you need, including essential backup software, the best open source partitioning utility and a choice of distros. Follow the instructions to live boot or install your software and distros from the disc. Featured software: Ubuntu 16.04 The perfect everyday distro for all-round use, the latest version of Ubuntu offers unparalleled convergence across your desktop and mobile devices. This distro live boots from the disc. Arch Linux Want to explore a command-line interface on your Linux PC? Arch Linux offers you exactly that. It’s the perfect introduction to command-line computing as it aims to offer a lightweight and flexible distro…

Top 10 This month Stable releases (18) In development (10) While there’s nobody particularly new in the top 10 this month, the latest Linux Mint update has seen it rocket to the top of the download list. Highlights Mint The beta release for Linux Mint 18 ‘Sarah’ launched to a lot of fanfare, promising widespread changes in its design and overall usability. For new users, it remains one of the easiest distributions to get your head around. Fedora Expect Fedora to dramatically go up the rankings over the coming months with the release of Fedora 24. As usual, there’s three different editions to test, with each bringing a unique set of features. elementaryOS The stylish elementaryOS also released a big update this month, with its Loki beta providing a plethora…

Spark plays just a small part in the grand scheme of things when it comes to the Apache community. The Apache Software Foundation (ASF) provides a series of open source software projects, aimed at providing high-quality software that leads the way in its field. But it’s the community part that resonates the most, as many of these projects are purely community-driven, with many sharing the same developers and end users. The ASF currently has a high number of volunteers who help develop and steward over 350 open source projects that cover a wide range of technologies. The choice is so vast, there’s something there for everyone. How about Jena, a Java framework for building semantic web and linked data applications? Or maybe SpamAssassin, providing a quick way for administrators to…

Even though repartitioning tends to be a very safe operation, it’s important to perform a backup before following any of the steps shown in this guide. Power outages, typing mistakes or the infamous lab aide tripping over a power cable can all cause problems that are almost impossible to fix without the (pricey) services of a data repair lab. The safest way to get into the fray involves the use of an external hard disk. Replicate a hard disk image, or copy a selection of important files and – this is crucial – disconnect the external HDD from your workstation. Some IT security professionals even go so far as to recommend the purchase of multiple external hard disks, one or more of which are stored off-site and which are updated…

While power users will probably want to stick to the instructions for manual customisation, average owners of GRUB installations are better served with an automatic installer. Sadly, the GRUB Customizer is not part of the official Ubuntu distribution at the time of writing. Instead, it must be downloaded from a third-party PPA, which must be added to the apt-get repository list. Simply feed a terminal with the following commands one by one, and follow the instructions on the screen: Next, open the Dash and look for the search string “GRUB Customizer”. Starting the program yields a threetab interface – the List Configuration tab lists the various operating systems configured, while the General settings tab allows you to customise the waiting time and the default entry selected after machine power-up. Change…

Dedicating one hard disk to each operating system is the most efficient approach. Sadly, both workstations and notebooks can mess up your plans – most notebooks smaller than 17 inches have just one hard disk bay, while modifications on workstations can turn out to become an annoying bit of work. As a complete reinstallation of the operating system is also tedious, reducing the size of partitions becomes an attractive alternative. This step is the most risky one of all outlined in this tutorial – please make sure you perform a backup at this stage. Line me up Moving partitions tends to wreak havoc with bootloaders. Due to this, we usually shrink them by cutting parts off their back – a process which requires that all relevant information must be at…

“Scripts will be able to reject invalid input on the fly, keeping clumsy or technically uninitiated users safe” Resources Workstation with Bash shell DOS-based Bash files have resulted in a spoilt generation of programmers: their largely linear execution entombed the perception of shell scripts as uninteresting simpletons. This could not be further from the truth. Bash provides script coders with a set of control structures that justly deserve a comparison with the ones found in programming languages such as JavaScript or C. When using them intelligently, scripts can be customised on the fly: manual rewrites are replaced by the analysis of the execution environment. Even more advanced possibilities are opened up by the usage of the input handling features of Bash. After having worked through the entirety of this tutorial,…

“Though time tracking is crucial for a project it is also very time consuming to enter data manually after each task” Resources Ganib http://www.ganib.com/ Software development is one of the fastest growing fields in IT, but it has its own problems. There are remotely distributed teams, working on the same code repository. There are changing priorities and deadlines. There are changing requirements and new technologies coming up. In addition, with its intangible outputs, software development proves very difficult to measure. So how do you manage all this while making progress? Agile development methodology has given us some hope. Agile focuses on the end product, while ignoring trivial things like lines of code written or man-hours spent, thus eliminating the need to measure effort and rather measure the completion of the…

£38/$49.90 • Udoo.org CONNECTIVITY One USB 2.0 Type A port and one USB OTG (micro-AB connector), plus fast Ethernet RJ45 – 10/100Mbps, Wi-Fi 802.11 b/g/n, Direct Mode SmartConfig and Bluetooth 4.0 Low Energy DIGITAL I/O PINS 32 extended GPIOs (A9 dedicated); 22 Arduino GPIOs (M4 dedicated). Arduino-compatible through the standard Arduino pins layout; compatible with Arduino shields PROCESSOR Freescale™ i.MX 6SoloX applications processor with an embedded ARM Cortex-A9 core and a Cortex-M4 core While the UDOO NEO may look like a fairly standard microcomputer, it is in fact one of the few that really looks to do things a bit differently. Its primary unique feature is its heterogeneous processor, which combines the power of a 1GHz Cortex A9 processor with the added power of a Cortex M4 processor as well.…

£37/$55 • Beagleboard.org HDMI video out, double the RAM and an improved processor that takes it over the all-important 1GHz bar. It’s also one of the better choices when it comes to project creation, with a total of 92 connection points on hand for your projects, which will appeal to both new and seasoned users. But if you’re stuck for ideas, there’s a thriving development community behind BeagleBone, which lists a wide number of beginner projects you can attempt. Simplicity is key when it comes to the BeagleBone Black, and everything from the initial setup process to attaching external devices is all made as pain-free as possible. It boasts that you can go from zero to Linux in under ten seconds and be developing on the board within five minutes.…

The first step is to open a serial connection to the Arduino “The Raspberry Pi is a truly amazing single-board computer that gets used in lots of DIY projects. That has been the basis for this whole column and the previous several articles. While the Raspberry Pi has a GPIO and can communicate with sensors and actuators, you may have cases where you want to use your Raspberry Pi as the brains of your project and offload the interactions with the physical world to another system. This is usually handled by one of the many microcontroller boards that are available. In this issue, we will specifically use the Arduino board and see how to connect it to a Raspberry Pi and how to handle the communications between the two. As…

What you’ll need Wireshark Another computer, laptop, or even a Raspberry Pi Large SD Card or mounted HDD storage Compilers from Most of the time when you install an application in Linux, you do so via a package manager, which enables the download and installation of binary packages, built from source packages. These include the default options, general features and parameters so that a wide portion of users can install without any problems. However, if you’re developing code, you first need to create a source package, and on a Raspberry Pi this can seem to take forever. One option is to copy the code to a desktop or notebook computer running Linux, but wouldn’t it be far more convenient to just let the Raspberry Pi deal with it… but give…

Major Tim’s months on the ISS have seen an increase in interest in all things space-related. If you’ve got that old telescope or binoculars out, dusted them down, and started searching the heavens, you’ll know the real difficulty is finding anything, and knowing when to look. An ephemeris – from the Greek word ›››››››› , a diary – gives the position of heavenly objects (natural and artificial) at a given time, and given the calculations involved to project the positions of astronomical objects, it’s no surprise that they’ve been computerised from the very earliest days. Nowadays there are online services, but having an ephemeris on your laptop frees you from data connectivity worries when out with your telescope. wxEphe is a wxWidgets-based application – easy to install given a few…

“Apache Spark is a fast and general engine for data processing, used primarily by data engineers, data scientists and business analysts. It provides high-level APIs in Scala, Java, Python, R and SQL. It also supports a rich set of higher-level tools that make it attractive for machine learning, graph computation, stream data processing, ETL and business intelligence. In a way, it’s the Swiss army knife of data processing. Spark was originally started by Matei Zaharia at UC Berkeley in 2009, and was donated to the Apache Software Foundation in June 2013. Spark became an Apache Top-level Project (TLP) in February 2014. Apache Spark has seen rapid adoption by enterprises across a wide range of industries. Internet powerhouses such as Netflix, Yahoo and Tencent have eagerly deployed Spark at massive scale,…

“Linus Torvalds announced Linux 4.7-rc6, traditionally the penultimate candidate prior to final release of a new kernel. Not too much stood out, other than that Linus was a little concerned by the growth in size of RC6 vs prior RCs. Generally, each release candidate should get smaller as the bar to pulling in fixes grows higher and higher toward the tail end of a cycle. Disruptive changes should instead come in via the next merge window: the couple of weeks during which well-tested changes are incorporated at the beginning of a cycle. Linus asked aloud, “one-time fluke or bad pattern emerging?” We’ll find out next cycle. Perhaps the most interesting feature that will be available to readers in Linux 4.7 is that of parallel directory lookups. The various filesystems (such…

Graphical disk overview GParted provides a diagram of the partitions as they appear on the hard disk. This is interesting, as partitions usually can only grow “backwards” – if a partition structure looks irrecoverable, starting over can be the best choice Choose your file system wisely Partitions can be formatted in a variety of file systems. If a partition is intended to be used by different operating systems, the primitive FAT32 tends to be the best choice This space is empty The partition of the example workstation is not used fully. Unallocated space is not used by anything, and should be allocated to a partition to make it accessible for file storage How partitions work The most basic installation – well known from Windows – consists of one partition per…

01 What’s what? GRUB finds its settings at runtime by parsing the file /boot/GRUB/GRUB.cfg. Editing it directly is, however, considered an antipattern – instead, the settings found in /etc/default/ GRUB are to be transpiled into a .cfg file using the sudo update-GRUB command. While not adhering to these rules does not usually lead to a non-working system, be aware that GRUB and kernel updates sometimes cause a complete recompilation of the GRUB config. In that case, any changes applied by hand will be lost and cannot be recovered easily. 02 Get editing The user-facing settings – think waiting times, backgrounds and the like – are stored in the file /etc/default/GRUB. It can be opened by entering sudo gedit /etc/default/GRUB into a terminal window of choice – the editor will then…

Everyday Ubuntu You might not love Mark Shuttleworth’s operating system. It, however, has done more for desktop Linux than most other distros and is excellent for everyday use. It’s also great for beginners. Everyday Debian Being the distribution that brought the world the apt package manager definitely earns Debian a place in this list. It is a decent everyday Linux for all who dislike Mark Shuttleworth... Oddball Chromium The operating system powering Google’s feature-reduced micro notebooks can also run on your workstation of choice – but be aware that this distro limits you to web apps! Enterprise CentOS Take Red Hat’s legendary reliability and remove the commercial support to end up with CentOS. If you ever felt a need to effortlessly deploy advanced enterprise software, this might save you a…

01 Install media Just like with all other operating systems, the life of a CentOS installation starts out with the downloading of an ISO file. It must then be burnt onto a DVD or a USB stick (you can get the Minimal version via our disc this issue), which finally serves as boot-up media for your workstation of choice. Use the up and down keys to select Install CentOS 7 when prompted – the live mode feature of the installation medium is not particularly useful for this tutorial. 02 Pick language and keyboard CentOS’s installation process is squarely aimed at professionals. Even though the user interface tends to update quite quickly after selecting language and keyboard layout, users are well advised to wait until the callout symbols next to Installation…

“If you compile legacy code in a newer GNU/Linux distro, chances are that it will be built without protections” Resources Smashing the Stack for fun and profit http://bit.ly/29p2p1F Debian Hardening https://wiki.debian.org/ Hardening GDB Quick Reference http://bit.ly/290eCIn Running shell-code http://bit.ly/295jT3a Relocation Read-Only http://bit.ly/2947QnV Software security is a complex area of expertise. We’ve left behind the heyday when smashing the stack for fun and profit was, so to speak, a piece of cake. Nowadays GNU/Linux distros ship with modern protections against memory corruption out-of-the-box, rendering these sorts of attack more improbable. And yet, security researchers are always finding obscure ways to exploit software flaws even with these protections on. Hardening your binaries can help you prevent most of these attacks. The GNU C library and the compiler offer some of these protections,…

“A virtual machine can be running Windows, Fedora, another Linux system or just about any other operating system you want” Resources Beginner Geek: How to Create and Use Virtual Machines http://bit.ly/1m5yDms All about virtualisation http://bit.ly/29elzoY Setting Up a New Virtual Machine http://bit.ly/29ekfmd Using the Ubuntu system as a virtualisation host, you can run multiple operating systems on a single computer. The systems you create on the host are referred to as virtual machines (VMs). A VM can be running MS Windows, Fedora, another Linux system or just about any other operating system that can run directly on the computer architecture of the host. Once a VM is installed, you can work with it in the same way as you would work with the operating systems installed directly on computer hardware.…

£108/$139.99 • Solid-run.com One of the new microcomputers to hit the market, the SolidPC Q4 can boast that it’s one of the first microcomputers sporting an Intel Braswell processor. For end users, it provides all the tools for hooking up a monitor and keyboard, while developers can experiment with the scalability of the Braswell chip. Other features include a microSD card interface, dual Ethernet ports and DisplayPort support for two displays. Stock of the SolidPC Q4 is relatively low, so to get your hands on one you’ll need to be quick.…

While you can write your own code to run on the Arduino, there are several projects that can be uploaded to it to make interacting a bit easier. One of these is the Firmata project, which includes a Python module to help you talk to the Arduino. The first step will be downloading the Firmata Arduino code and uploading it to your Arduino, most easily done with a desktop computer. The code is available at github.com/firmata/arduino. There are a few different versions available, but for these examples you should upload the StandardFirmata sketch with the Arduino IDE. There are client libraries available for many different programming languages, including several for Python. The one we will look at using is pyFirmata. You can install it on your Raspberry Pi with: You…

What you’ll need ArticlesGithub repository ( Raspberry Pi Zero microSD Card All other kit is listed in step 1 In part one in the previous issue we read Wikipedia’s definition of a robot as a machine capable of carrying out a series of actions automatically (paraphrased). We then gave an overview of all the considerations you may have for your build, from the chassis to the motors to the sensors you may want to add for autonomous tasks. In this issue we invite you to join us as we build our own model robot. If you follow along, you should have everything to get you started especially if this is new territory for you. We are going to build your explorer robot from scratch running through each step…

This is a bit of fun: a media player framework, written in Bash, that will use various players as a back-end. It also has a serious use in embedded systems, where resources are scarce, but for those who spend most of their time using a virtual terminal, the appeal will be a player with some useful features, yet written in that most humble of scripting languages, Bash. PlayShell, when first started, will search your system for media players. It works with VLC, MPlayer, SoX and FFPlay, and is capable of using some more minimal players like amp, aplay, gst123, madplay, mpg321, mpg123 and splay. As a Bash script it can be run directly where it’s unpacked, but it also comes with an install script, which gives you configuration files and…

“They are simply dedicated to providing customers with the highest quality VPS service with exceptional uptime and competitive pricing” Featured host:   sales@bhost.net About BHost BHost specialises in one thing and doing it right: Linux Virtual Private Servers (VPS). BHost doesn’t sell extras like domain names or SSL certificates – they are simply dedicated to providing customers with the highest quality VPS service with exceptional uptime and competitive pricing. BHost’s customer focus means that their team always goes above and beyond to help. Their platform successfully hosts a whole variety of services, including game servers, office file storage servers, email and DNS servers, plus many thousands of websites. BHost is confident that you will love their service. However, if for any reason you’re not completely satisfied, they will provide…