Linux User & Developer的No. 166目录

This issue » Make with micro:bit » Build a web radio » Learn Go » Lock down your online security Welcome to the latest issue of Linux User & Developer, the UK and America’s favourite Linux and open source magazine. We’re incredibly excited about the BBC’s new micro:bit and in this issue we explain exactly what it is, what it does and how it compares against the Raspberry Pi, plus we’ve got five maker projects to get you started, from simple LED hacks to building your own torch, dice and even a compass. Check it out on p14. We haven’t forgotten our beloved Raspberry Pi in all the excitement about the micro:bit though. This issue our experts explain how you can use your Pi as the heart of a web…

Top 10 This month Stable releases (28) In development (6) Mint is on top, while Ubuntu is down, despite dropping its long-awaited 16.04 long-term support release in the last month. elementary is a new entry this month Highlights elementary This Ubuntu-based desktop distro features its own custom desktop environment called Pantheon and is ideal for Linux newcomers. It has a bundle of custom apps including Photos, Music, Videos, Calendar, Terminal, Files, and more, as well as some familiar ones like Midori. Fedora Fedora features custom versions called Fedora Spins built with specific sets of software packages, offering alternative desktop environments or targeting specific interests such as gaming, security, design, scientific computing and robotics. Zorin Zorin is designed to offer an alternative OS to Windows users, and packs in lots of…

We’re giving five lucky readers who are starting out in the world of programming the chance to win a copy of the latest title from Haynes. The Raspberry Pi 2 Owner’s Workshop Manual contains invaluable step-by-step guides to get your own small computer project up and running. The manual covers all aspects of the Raspberry Pi 2, intervening models and the model Zero. Guiding readers through the full process of setup and configuration, computing and programming, the manual offers a series of ‘recipes’ that demonstrate the versatility of the device’s hardware and software. For your chance to win just email your name and contact details to linuxuser@imagine-publishing.co.uk, along with your answer to the following question: What is the successor to Raspberry Pi called? a) Blueberry Pi b) Steak and Ale…

Step Counter http://bit.ly/1T9SwHl Keep track and monitor how many steps you take each day by creating your own simple pedometer. This uses the built-in accelerometer and LEDs. Attach it to your leg or shoe and check the micro:bit’s display for the number of steps you have taken. Musical Fruit http://bit.ly/27j37FY Take some fruit or vegetables and combine them with the micro:bit to create a musical instrument. Touch each piece of fruit to trigger a musical note, drum beat or sound. Football Scoreboard http://bit.ly/1T9SH5a This project combines a few household items to create a goal which when hit, triggers a buzzer and displays a winning animation. Use the setup in this project to build a score board for a football game or any game of your choice. Fortune Teller http://bit.ly/24V4g7O Code…

Code Kingdoms JavaScript JavaScript www.microbit.co.uk/cs A visual drag-and-drop editor where you select blocks of code and drag them into the script area, building up your program. You can switch between blocks and plain text and there are a number of example programs to get you started. This makes this editor the most suitable for beginners. Microsoft Block Editor Block editor http://bit.ly/24PFa72 Block editor is an advanced visual drag-and-drop interface where you snap code lines together. It introduces a wider range of functions and procedures, which enables you to create more complex and customised code. You can also convert the code into fully compatible Touch Developer scripts. Microsoft Touch Developer Touch Developer www.microbit.co.uk/td/contents Touch Developer is both a text-based and ‘touch’ editor, designed for touchscreens. It works across a range of…

01 Set up a simple script This first project covers most of the elements that you will need for creating future scripts. Open your web browser and navigate to the micro:bit website at https://www.microbit.co.uk. At the top left of the page click my scripts and then select the Create Code option. You will be presented with the main programming languages. For all the projects we will use Touch Developer, so select this. You will be presented with the main coding window which contains a random script name and the place holder for a function. This is where the main code sits. Rename the script to something more identifiable such as, “my first script”. 02 Add the button press Now select the middle line between the function start and end lines.…

Mihalis Tsoukalos Mihalis Tsoukalos is a UNIX administrator, a programmer (UNIX & iOS), a DBA and a mathematician. He has been using Linux since 1993. You can reach him at @mactsouk (Twitter) and http://www.mtsoukalos.eu/ Resources Iproute2 https://en.wikipedia.org/ wiki/Iproute2 http://www. linuxfoundation.org/ collaborate/workgroups/ networking/iproute2 The study of TCP, UDP and UNIX socket connections is important for every UNIX and network administrator as it allows you to see how your Linux system is doing. Many command line utilities exist that can help you get statistics on your network connections, including the famous netstat utility, which has been replaced by the more capable ss utility, the subject of this tutorial. As you will see, the ss utility is part of the IPROUTE2 Utility Suite, which will be further investigated in the next issue of…

Nitish Tiwari is a software developer by profession, with a huge interest in free and open source software. As well as serving as community moderator and author for leading FOSS publications, he also helps organisations adopt open source software for their business needs. Resources Amp Project https://www. ampproject.org/ Accelerated Mobile Pages, aka AMP, is a Google initiative that helps you make sure your website is optimised for mobile content and can load instantly everywhere. AMP is a way to build web pages for static content that renders fast. AMP has three different parts that help you achieve this: AMP HTML, AMP JS, and Google AMP Cache. 01 Introduction Most of the tags in an AMP HTML are regular HTML tags, with few of the tags replaced with AMP specific tags…

openArtist http://openartisthq.org/ Optimised with working graphics drivers and stuffed full of tools designed for digital artists, openArtist manages to be a creative Linux environment while simultaneously supporting the open source ethos. Also now with an updated list of new artist tools for Linux. gnuArtist http://gnuartist.linuxfreedom.com/ An artistic distribution based on Xubuntu, gnuArtist features a collection of multimedia software covering everything from creation and editing (3D modelling, animation, video and music editing) to DVD authoring and programming. If you’re creatively inclined, check it out. dyne:bolic https://www.dyne.org/software/dynebolic/ Launched in 2000, dyne:bolic is probably the original creative Linux distro, and includes tools such as Scribus for desktop publishing, Audacity, JACK, and Jammin for audio work, Cinelerra video editor, GIMP, and more. It also features strong data encryption. KXStudio http://kxstudio.linuxaudio.org/Downloads KXStudio is available in…

There are modules available to detect magnetic fields The Raspberry Pi was designed to provide several ways to interact with the world through sensors and activators. In the past, we have looked at using the GPIO interface pins to communicate with several devices at once. This is not the only way to work with the world at large, however. This month, we will look at one of the other mechanisms available, the I2C bus. I2C (Inter-Integrated Circuit) bus was invented by Philips Semiconductor, with version 1 having come out in 1992. The design is for short connection paths, and supports multiple masters and multiple slaves where messages on the bus are delivered using device addresses. Messages have a START section and a STOP section, wrapped around the core of the…

What you’ll need • Raspberry Pi (V2B recommended, V1B possible) • Decent quality MicroUSB power supply • Cardreader + MicroSD Card • Compatible USB-Ethernet adapter (i-tec-europe.eu/?t=3&v=296i-teceurope.eu/?t=3&v=296) • Optional, but recommended: Ethernet switch (no router!) Controlling the interconnects between various devices is paramount to keeping systems secure and safe. Sadly, most router operating systems are closed source – finding vulnerabilities in them is difficult to impossible. Sadly, running dedicated open-source router operating systems is not a solution for the average user, as they tend to demand high-end hardware with prohibitively high prices. OpenWRT is an affordable and efficient alternative. It foregoes some of the complexities found in traditional router operating systems, thereby allowing for lower hardware requirements. The community has ported the system to various routers: with a little care, a…

Clementine has been steadily improving for a while; getting more stable, and carefully improving features. TheAmarokinspired player has always been notable for its quick and easy management of music collections, as the developers stay focused on the core priority of a simple interface to play your digital music. With packages available for all recent versions of Fedora and Ubuntu, it’s easy to install the latest version on any Red Hat or Debian-based distribution. Getting started is easy, whether opening a file or folder of music, or naming a new playlist, and adding files. While you can have multiple, tabbed playlists, the default operations are always available with the fewest clicks, and the interface is also pleasingly responsive. Last.fm integration, visualisations, podcast discovery, and the other bells and whistles like artist…

“What was it like working in technology at a time when computers were transforming so radically? I don’t really think that this transformation has come to a halt: it’s not something that happened 30 years ago, then stopped! Today’s technology is still more exciting that it was only a few years ago, just as it always has been. I notice that the wheel gets reinvented every so often, but probably that’s nothing new either. So when did you first start using the Raspberry Pi yourself – and when did you become involved with the Raspberry Pi Foundation and the device’s inventors? I started using it pretty early on. I was one of the small number of engineers at Broadcom in Cambridge who try to make new chips usable for people…

“Linus Torvalds announced the release of Linux 4.6-rc7 (Release Candidate 7), noting that there was “Nothing particularly scary, and the more people who test this out, the more confident we can be that the final 4.6 is all good.” Traditionally, there are seven release candidate kernels – one per week on a Sunday evening US Pacific time – following the closure of the (roughly) two week “merge window”, for a total of ten weeks of development for each new kernel release. Occasionally, these cycles can go slightly longer, and even more rarely they run short. Linux 4.6 was one such cycle that might have ended after RC6, and Linus did mull that option aloud, but in the end he says it never “got *so* quiet that I would decide that…

Raspberry Pi 2 CPU: 900 MHz 32-bit quad-core ARM Cortex-A7 GPU: Broadcom VideoCore IV RAM: 1 GB (shared with GPU) Networking: 10/100 Mbit/s Ethernet (8P8C) USB adapter on the USB hub GPIO: 17 Ports: USB x 4, HDMI, composite video, 3.5mm audio jack Storage: MicroSDHC Programming languages: Python, BBC BASIC, C, C++, Java, Perl, Ruby, Squeak Smalltalk Extras: SPI, DPI Raspberry Pi 3 CPU: 1.2 GHz 64-bit quad-core ARM Cortex-A53 GPU: Broadcom VideoCore IV RAM: 1 GB (shared with GPU) Networking: 10/100 Mbit/s Ethernet, 802.11n wireless, Bluetooth 4.1 GPIO: 17 Ports: USB x 4, HDMI, composite video, 3.5mm audio jack Storage: MicroSDHC Programming languages: Python, BBC BASIC, C, C++, Java, Perl, Ruby, Squeak Smalltalk Extras: SPI, DPI Raspberry Pi Zero CPU: 1 GHz ARM1176JZF-S single-core GPU: Broadcom VideoCore IV RAM:…

01 Add some text Set up a new script as you did in the previous project, naming the function and selecting the third line down. Next select the ‘input’ block and ‘on button pressed’. The default button A is shown. On the next line, select the ‘basic’ block and this enables you to select the ‘show string’ option. Now add your sentence of text, for example, “I can code a button”. 02 Add the animation Now add button B; this is the same code structure as in step 1. However, before adding this ensure that the previous code line is closed, using the ‘end’ code. The simplest way to do this is to select the plus symbol to add a new line. Click on the ‘input’ block and ‘on button…

01 Calibration The first step is to set up the calibration for the compass. This ensures that it runs accurately. Start a new script and rename it, then select the ‘input’ and ‘calibrate’ blocks. When you run your program, this section of the code runs a little game where you rotate the micro:bit and draw a circle on the LED display. 02 Looping and variables A variable can be thought of as a box in memory which stores data. In this project the compass heading angle is stored. This heading will change as you rotate your micro:bit, so you need to constantly check the heading and store it in the variable. This is known as a ‘forever’ loop. Set the loop up in the function, click the ‘basic’ block and…

Swayam Prakasha has a Master’s degree in computer engineering. He has been working in information technology for several years, concentrating on areas such as operating system, networking, network security, electronic commerce, internet services, LDAP, and web servers. Swayam has authored a number of articles for trade publications, and he presents his own papers at industry conferences. Resources File system administration http://oreil.ly/1SAJuiN The Linux system administration guide http://bit.ly/1rBZWcj The Linux System Administration and Configuration http://bit.ly/1N2N1tt Linux system administration commands http://bit.ly/1SC5fPk File systems provide the structures in which files, directories, devices and other elements of the system can be accessed in Linux. The most commonly supported file systems in Linux are ext4 and NTFS. Some flavours of Linux such as Ubuntu give you an option of either having the installer create a…

Mihalis Tsoukalos Mihalis Tsoukalos is a UNIX administrator, a programmer (UNIX & iOS), a DBA and a mathematician. He has been using Linux since 1993. You can reach him at @mactsouk and http://www.mtsoukalos.eu/ Resources A text editor such as Emacs or vi The Go compiler Go is an open source systems programming language that makes it easy to build reliable and efficient software. Part of its greatness comes from the fact that Go supports many data types and allows you to build new ones easily. The data types that do not belong to the basic data types are called composite data types. Combining basic data types together generates composite data types. A composite data type can also contain another composite data type. Although composite data types look pretty simple, it…

You may know about Blender already, perhaps as a tool for creating 3D figures, or titles… but it can do so much more than that. A quick visit to YouTube will see the software filling in the role of physical modelwork, perhaps as a CGI TARDIS or more traditional spaceships, weaponry, even people. However, it can also be used for less direct elements, such as adding smoke or explosions or other VFX to a video project, and producing set design items that are too expensive to physically build. Unlike most of the other creative tools we’ve featured this issue, however, Blender has a steep learning curve. While it can be relatively simple to get started and find your way, it requires focus to translate this into usable results. Short effects…

The Raspberry Pi has another communication bus available for you to use, called the SPI bus (Serial Peripheral Interface). It is similar to the I2C interface, except it only allows for a single master. The SPI bus is also not active by default.; you will need to activate it, either manually or by using the ‘raspi-config’ utility. You will also need to install the relevant python module with Once you have SPI activated and the spidev module installed, you can initialise the bus with the code The next step is to open a connection to the device of interest. To do this, you need to use the function The two parameters in the open function are the bus and device IDs for the device you want to talk to. When…

What you’ll need • Github repository (http://github.com/alexellis/ pyPlaylist) • pimoroni pHAT DAC £10-12 (pimoroni.com) • Soldering iron, flux & solder We will show you how to create a high-quality networked music player that takes advantage of the UK’s online radio stations, Linux’s popular Music Player Daemon, and a responsive web-server to control it all. The full-sized Raspberry Pis have two built-in audio outputs: audio over HDMI cable and a 3.5mm headphone jack that can suffer interference and noise. The Pi Zero itself has no audio jacks but Pimoroni has come to the rescue and built a high-quality DAC (digital audio converter) using the same chip as the Hi-Fi berry (PCM5102A). 01 Soldering the headers The pHAT DAC comes with a 40-pin header, which you will need to solder. We consider…

Idris is “a general purpose functional programming language with dependent types”. Types can depend upon values; as a first-class language construct they can be manipulated like any other value. What this means in practice is demonstrated in the official tutorial, for example as part of an interpreter, where types are calculated. Although a relatively new language, there are several other tutorials available, with most assuming some familiarity with Haskell or OCaml. Given such a grounding, should you spend time on an even less-used language? Most certainly: functional programming languages of today are the proving ground for features that could in the future be indispensable, as we struggle to adapt our programs for a decoupled, multiprocessor (or multi-machine) world, for example with Idris type-checking against the code’s signature as a sanity…

A state-of-the-art data centre environment enables Netcetera to offer your business enterprise-level colocation and hosted solutions Get your listing in our directory To advertise here, contact Luke luke.biddiscombe@imagine-publishing.co.uk | +44 (0)1202586431 Featured host: www.netcetera.co.uk 0800 808 5450 About us Formed in 1996, Netcetera is one of Europe’s leading web hosting service providers, with customers in over 75 countries worldwide. As the premier provider of datacentre colocation, cloud hosting, dedicated servers and managed web hosting services in the UK, Netcetera offers an array of services designed to more effectively manage IT infrastructures. A state-of-the-art data centre environment enables Netcetera to offer your business enterprise-level colocation and hosted solutions. Providing an unmatched value for your budget is the driving force behind our customer and managed infrastructure services. From single server to…

“One important aspect is simply democratic feature selection. The job that open software does is not dictated by a commercial entity, it is what the users and the developers want. “In principle a lot of contributors means that there are a lot of eyes reading the code. And while that is not the only way to improve the quality of the code, it may improve its quality and, even if it does not, the code is at least available for anyone to correct. So my next important aspect of free software is simply that it is more capable of becoming bug-free than non-free software. “My third and final important aspect of free software is to do with your personal development. Good free software does not go away… the longevity of…

Bluetooth Built-in Bluetooth Smart Technology enables you to connect to other devices such as your phone, laptop or tablet. Or connect the micro:bit to peripherals to create your own Internet of Things. MicroUSB Use the USB connection to power your board when connected to a Windows or Mac computer. This enables you to download or ‘flash’ programs onto your micro:bit. You can also send data from your device back to the computer. Battery Pack This socket allows you to connect an external battery pack containing two AAA batteries to the board. This makes your micro:bit mobile and you can run your programs externally.…

Resources Password Store https://pwsafe.org/ Vaultier.org http://www.padlock.io/ As internet users, a lot of us struggle with log-in forms. Thousands of hours are lost in this quest to recall, retry and reset one’s password on a daily basis. The number of password managers available online is huge, but still the adoption is quite low. This is primarily because users are often not aware of various password managers and their strengths and weaknesses. And even if they are aware of them, security concerns often deter them from using a decent password manager. But with password managers, not only will you be able to create hard-to-guess passwords with ease, but also make sure you have different passwords for all your different accounts and that you change those passwords on a regular basis. In this…

Toni Castillo Girona Toni Castillo Girona holds a bachelor's degree in Software Engineering and works as an ICT research support expert in a public university sited in Catalonia (Spain). He writes regularly about GNU/Linux in his blog: disbauxes.upc.es. Resources GNU Make gnu.org/software/make/ GNU Make Debugger sourceforge.net/ projects/gmd/ GNU Make Standard Library gmsl.sourceforge.net/ Remake bashdb.sourceforge.net/ remake/ Any GNU/Linux flavour has a package manager, full of pre-compiled binaries, which makes installing new software a no-brainer. And yet, sometimes we do need to compile software from its sources, i.e. the package manager does not have a particular piece of software in its repository, we want to use a different compiler, we need to set different compiler flags to generate the binary, and so on. More often than not, this compilation procedure involves some…

Linux doesn’t have its own version of Adobe Creative Suite, but that doesn’t mean that you cannot complete video editing, image manipulation, illustration or audio recording and editing projects on your Linux PC. Over the years, an increasingly wide-ranging collection of tools has been released on Linux, almost all open source, and each being a realistic alternative to its closed source, more well-known brethren. For instance, GIMP has long been used as an open source alternative to PhotoShop, and various video and audio editors can be found on Linux. On the whole, however, the creative world hasn’t really had a good run on Linux. Until now. So, forget about looking wistfully at your colleague or competitor’s Mac or Windows machine, discard the Wine and its occasional usefulness; limit your use…

The trickiest part was capturing the game board accurately David Pride has been working on various Raspberry Pi projects for a number of years, with many of his creations showcased across the UK. Like it? Puzzle-solving Pi robots are always well received, and if you like the look of David’s Connect 4 robot, go ahead and check out this Rubix cube solving robot from Maxim Tsoy. It’ll be a while before it can beat the world record, but it isn’t far off: http://bit.ly/1SvrIQ6 Further reading A large part of the development of the Connect 4 robot stems from the Minimax algorithm. It’s fairly complex, but adaptable to a wide number of projects and useful when mixing motors and servos with the Raspberry Pi. A complete guide to the algorithm can…

What you’ll need Wireshark (www.wireshark.org) PiCam module or USB webcam While you’re settling down to enjoy your latest boxset, there’s always that nagging feeling at the back of your mind – is the baby asleep, or crying down the house? Surround sound tends to get in the way, which means we need to rely on baby monitors. While audio monitors are useful, the trend these days is more towards video baby monitors, in particular those that display footage on an app or by opening an IP address in a mobile browser. Throw in some motion detection and alert software, and you’ve got an incredibly useful tool – which, you won’t be surprised to learn, the Raspberry Pi can do for a fraction of the cost. All you’ll need is a…

“Parsix has changed very little when it comes to the look of the desktop, which, while some may call it lazy, is still functional” Hard drive 1.2GB Storage 4GB CPU Dual-core minimum Available from www.parsix.org Parsix GNU is one of the few distributions that has managed to keep up with the times, consistently changing its feature set in the quest for expanding its user base. Despite increased competition from a number of emerging Debian-based distributions, Parsix GNU continues to dazzle, with its latest 8.5 update once again showing why it deserves new users to check it out. Despite the installer not being particularly beginner-friendly, the text-based Xdialog menu system gets the job done. Root options are available and the ability to partition a hard disk is also included. Of course,…

Audio and video files contain plenty of info about their content, encoding and container formats, and there’s no need to try and play them in order to find out more than the filename and size. MediaInfo is a handy little utility for displaying information about everything from subtitles to container format. Supported video formats include MPEG-1/2 Video, H.263, MPEG-4 Visual (including DivX, XviD), H.264/ AVC, H.265/HEVC, and FFV1. Audio embraces MP3, AC3, DTS, AAC, Dolby E, AES3, and FLAC. Add in every subtitle format we know, and most open containers – including unprotected Blu-ray – and MediaInfo has, well, media info covered. Much of the heavy lifting is done by libmediainfo0, with command line and GUI vesions of MediaInfo both available. These, and libzen0, are on the project website pre-packaged…

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