Linux User & Developer的Issue 538目录

This issue » Take charge of the command line interface » Protect your servers » Discover Pixel » Configure your desktop Welcome to the latest issue of Linux User & Developer, the UK and America’s favourite Linux and open source magazine. A while back we asked you how often you use the command line interface and what for, and the results were very interesting. While over half of you use it at least half the time, many of you pointed out that given the choice you’ll use the GUI because you’re more used to it, sacrificing the additional control you get from the CLI for ease of use. This set us thinking: what if we could break down the complexities and advanced techniques of the command line and give you…

Solus has gained an ever-increasing user base over the past 12 months, so it’s no surprise to see its latest point update garner a lot of praise. Solus 1.2.1 ‘Shannon’ has stayed faithful to its default graphical desktop called Budgie, but it now introduces a MATE version for the very first time. MATE has proven to be a good choice for low-power machines, offering the same user experience without being overly CPU-intensive. On top of the MATE release, Solus 1.2.1 introduces an updated Software Center application that caters for a wider selection of third-party apps, and provides on-the-spot system updates in real time. The eagle-eyed among you will also find the implementation of the Radeon Vulkan driver, support for the Intel Virtual Button and full compatibility with Microsoft’s Surface Pro…

One of the most startling things about the VoCore2 is its size. In fact at only 25.4 x 25.4 x 2.8mm, it’s touted as being the world’s smallest smart router. Despite its size, it still manages to pack in a lot of tech that closely rivals some of the more recognised brands out there. At its core is a 580MHz MT7628AN CPU, working alongside 128MB of DDR2 RAM. For most users, this will be more than enough power to partake in some basic program developing, but there’s plenty of room to expand on if necessary. Despite some constraints with the available antennae, VoCore’s dual system still manages to transmit 300Mbps wireless internet speeds. Alongside this, it also boasts Ethernet and USB hosting, UART, SD, SPI, I2C and potential for a…

“Java applications exist either in the shape of JAR files or of single classes, both of which must be executed by a virtual machine” Resources Bash gnu.org/software/ bash Eclipse IDE for Java developers bit.ly/2ebTIxH Java SDK bit.ly/2dhL8ed Java Runtime Environment bit.ly/1r2AXKi Connecting Qt applications to shell scripts is greatly simplified by their native nature: once compiled, a Qt application is very difficult to keep apart from a normal Linux program. Java applications are different: they exist either in the shape of JAR files or of single classes, both of which must be executed by a virtual machine. This part of our Bash masterclass will introduce you to interactions between Shell scripts and Java applications. We won't limit ourselves to exchanging parameters this time: the harness can also exchange data between…

Resources A text editor such as Emacs or vi The Go compiler In this tutorial, we’ll look at testing in Go using the testing package, the runtime package, the Go garbage collector and the Go pprof tool used for code profiling. As testing is an ongoing process that happens in parallel with the actual coding, you should not wait until you completely finish coding to start writing tests. This is the last tutorial in the Go series – you are now ready to do many great things with Go. The key to success is practice! Should you wish to learn more about Go, you should read books such as The Go Programming Language (Alan AA Donovan and Brian W Kernighan, Addison Wesley Professional Computing, 2015), Programming in Go: Creating Applications…

Switch to a new file manager File managers should probably be more functional than most bundled options (such as Nautilus). So consider alternatives, such as Konqueror, Midnight Commander, or KDE. Meanwhile if you prefer the simplicity of Nautilus, then consider something a bit closer to it, like Thunar or PCManFM. Change your window manager If you want to control or change the placement and appearance of the windows in your Linux distro, then you need to consider switching your window manager. A vast number are available, from Compiz and Metacity to Kwin and Mutter. Get ready to customise your desktop menus! Get a great looking dock The default Linux panel can be replaced with an OS X-style dock, if preferred, and this can either be implemented via a window manager…

So far we've looked at alternative desktops and distros, and considered re-theming with the help of new icon packs and system tools like the file manager. But what if you're more-or-less happy with what you've got, and simply feel things just need freshening up a bit? Well, if you're using Ubuntu, you'll find the Unity Tweak Tool in Ubuntu Software or you can install via the terminal instruction: Once installed, you'll be able to change the settings of several elements in the Unity desktop, from the number of desktops available to managing the position of the launcher and even tweaking the Dash menu. All in all, the options in the Unity Tweak Tool will enable you to improve the Unity experience, and finally begin to enjoy it… 01 Customise Launcher…

What you’ll need • Raspberry Pi (Ideally a Pi 2 or 3 if you want to use Chromium for streaming video) • If installing from Raspbian from scratch, an 8GB Micro SD card • Access to a computer for connecting via SSH and/or to install Raspbian Jessie with Pixel Pixel (Pi Improved Xwindows Environment, Lightweight), is the latest iteration of the Raspbian desktop. The major changes are apparent the first time you boot up – the multitude of boot messages has been replaced with a simple splash screen with the release number. There are now 16 stunning desktop background images to choose from thanks to Pi Foundation developer Greg Annandale. The icons on the file manager, task bar and menu now have a crisp, professional appearance. Menus are also cleaner…

RAM 2GB RAM Storage 10GB HD space Processor 64-bit Intel x86 Chapeau isn’t a distribution that vast amounts of the Linux community will have some real experience with, but it has long been heralded as one of the better Fedora-based distributions out there. While its core is pure Fedora, Chapeau takes a fairly lax approach to software licensing, choosing to implement software not permitted under Fedora’s licensing policies. It’s a trend that has proven to be a major part of Chapeau’s previous updates, and remains an integral element in Chapeau 24. One of the most pleasing aspects of Chapeau has been its relatively simple installation process. This isn’t a CPUintensive distribution, which is a pleasing nod to older machines, but there’s enough scope here to still cater for those who…

The original vi editor is now 40 years old, and Vim (Vi IMproved) is now 25, but it’s been more than a decade since the last major release, so 8.0 is, if not big news, at least worthy of investigation. Among the improvements are: Asynchronous I/O support, channels, JSON, Jobs, Timers, Partials, Lambdas and Closures, Packages, New style testing, Viminfo merged by timestamp, and GTK+ 3 support. After downloading, all you need to do is unpack, enter the src directory, and run make to generate a new Vim binary - then :help version8 will tell you more about the changes. “Vim isn’t an editor designed to hold its users’ hands. It is a tool, the use of which must be learned,” says the website with painful honesty. Like Emacs, its…

Welcome to the Linux User & Developer DVD. This issue, transform your desktop with a range of tools. Live boot Apricity OS ‘Aspen’ and discover its beautiful Cinnamon and GNOME environments, take a look at Elementary OS ‘Loki’ and its stunning Pantheon desktop, or fire up KDE neon to take the KDE Plasma Desktop for a whirl. Plus there’s Conky and Cairo-Dock to switch up essential parts of your Linux interface, and all the essential tutorial files you need to follow along with the tutorials in this issue. Please note that all the distros on this disc are designed for 64-bit architecture. Featured software: Apricity OS ‘Aspen’ Live boot the stunning GNOME interface of Apricity OS. Once installed, to switch to the Cinnamon version while running Apricity OS GNOME, open…

Network security has seen multiple exploits appear in recent years, but one to come into focus in the past few weeks has actually been in the wild for a number of years. This follows on from a warning from Red Hat, which indicates that the flaw is now being exploited on multiple desktops worldwide. Phil Oester, a Linux security researcher who was the one to initially uncover the flaw, has explained in a very recent interview with V3 that the exploit is actually becoming more widely used and at a rather alarming rate. “The exploit in the wild is trivial to execute, never fails and has probably been around for years – the version I obtained was compiled with gcc 4.8,” he also said. “An unprivileged local user could use…

Top 10 This month Stable releases (18) In development (5) Downloads, by and large, have been up across this month. A new wave of releases and updates has sparked downloads in some of the biggest distributions out there. Highlights Ubuntu Expect Ubuntu to rocket up the download list in the coming weeks. Its latest 16.10 update has improved flaws from previous updates, while also introducing some of the most asked for features by its user base over the past few years. Mint Despite increased downloads from its core competitors, Mint still holds a lengthy download lead over all of them. Linux Mint 18 has actually proven to be one of the most popular updates in recent memory. elementary Out of all the distros making the list this month, elementary has…

While the VoCore2 is an impressive piece of kit by itself, its usability is taken to the next level when using it in conjunction with one of the available docks. The Ultimate Dock is an impressive piece of kit, and dramatically increases the feature set of the VoCore2. Not only does it manage to cram in microSD, Ethernet and USB 2.0 ports into its tiny frame, but it also contains a four-channel AD converter and a single channel DA converter. Both of these converters are able to work wirelessly with a variety of sensors, but they will need to be purchased separately. Eagle-eyed developers will also find an on-board, driver-free serial port to USB, a handy tool to have around. Due to its size, you won’t find any bulky batteries…

You probably remember this from your schooldays: syntax is the rule book that governs the order we put words in to create flowing, well-formed sentences when writing and speaking. In programming, it’s pretty much the same. The only difference is, poor syntax when you’re writing or speaking to other people may cause some confusion but you’re likely to make yourself understood eventually, whereas in programming you’re likely to break things. Humans can make educated guesses as to what you’re on about; machines can’t – you need to explain what you want them to do in a way that they understand. This means learning and using the correct syntax. Each programming language has its own particular grammar and syntax (just like spoken languages). In addition to this, there are also regular…

Resources .NET for ‘any platform’ dot.net Get Started with ASP.NET Core asp.net/get-started Yeoman yeoman.io ASP.NET Core Yeoman Generator bit.ly/2cw2UKx Yeoman Generator for Dockerfile and Scripts bit.ly/2eisgO9 Docker docker.io Docker image repository for ASP.NET Core hub.docker.com/r/microsoft/dotnet/ Kubernetes kubernetes.io Open Weather Map API bit.ly/2dFr6K4 Author’s GitHub project examples bit.ly/2cEk8rP ASP.NET  Core represents the new thing in the world of .NET. Microsoft, together with an engaged open source community, has realised a web application development framework that can be harnessed in a variety of ways, including to develop.NET-based microservices deployed to Linux-based Docker containers. Leveraging the Docker approach and technology stack, a new approach to hosting, deployment and scaling of web APIs developed in C# is now possible. This article will briefly introduce the key aspects of developing RESTful web APIs with ASP.NET…

Resources Censys Engine https://censys.io Gitrob https://github.com/michenriksen/gitrob theHarvester http://bit.ly/1R8DaPr The Google Hacking Database http://bit.ly/1MvODnO Recon-ng http://bit.ly/18Dcs0F WhatWeb http://bit.ly/2dylVdp FOCA http://bit.ly/1eFHHMv Kali Linux https://www.kali.org/ Knowledge is power. Knowledge feeds on information and data, therefore we can increase our knowledge by gathering as much information and data as possible. Once we have all this new knowledge, we can make informed decisions. This is how attackers see our massive interconnected world of computers and networks: as an almost everlasting pool of sensitive information holding data that can be leveraged to gain a foothold on a system. Surprisingly enough, the vast majority of sensitive information that is exposed out there can be easily obtained by means of Open Source Intelligence (OSINT) or intelligence collected from publicly available sources. Data that can be gathered ranges from…

"A pure Python module that is fairly complete is Paramiko" Even with a small footprint, Raspberry Pis can still provide a powerful set of computing resources. This is the perfect combination for projects that are meant to monitor something. We will look at how to code up a system to be able to keep an eye on an important server that you need information about. There are several ways to do this. Since we have limited space here, don't forget to check out other options in case something else might work better in your situation. As with other articles in this series, we will be using Python to write the code that handles monitoring the external server. A properly hardened server should only allow encrypted connections over SSH from outside…

This is another venerable piece of software – Dr Geo is 20 years old! This is an interactive, educational geometry and programming environment aimed at teaching use, helping children to explore geometry. This latest release, in addition to several bug fixes, features “a new French programming API for French speaking kids: [the] programmed sketch can be written in French Smalltalk.” It’s 32-bit software, needing compatibility libraries, and these upset one of our test machines – but to be fair, we overload our boxes with clashing libraries. Installing on a reliable old 32-bit Ubuntu laptop (our Smalltalk test machine) was no problem – and if you have an old PC you keep for your kids to play GNU/Linux educational games on, that’s ideal. Users create and manipulate sketches, altering constraints to…

Live boot Insert the disc into your computer and reboot. You will need to make sure that your computer is set up to boot from disc FOSS Free and open-source software needs to be installed via the distros or by using the disc interface Distros Distros can be live booted so that you can try a new operating system instantly without making permanent changes to your computer Explore Alternatively you can insert and run the disc to explore the interface and content Important information Check this before installing or using the disc For the purpose of this disclaimer statement the phrase ‘this disc’ refers to all software and resources supplied on the disc as well as the physical disc itself. You must agree to the following terms and conditions before…

1 C.A.IN.E Despite its odd name, C.A.IN.E is the distro of choice for those needing to perform computer forensics, aiding detectives throughout their investigations. It focuses on a user-friendly front-end, and can be installed on a hard drive, or run from a live CD. 2 Gentoo The reason Gentoo has a small, but loyal, following, is because it’s one of the few distros that enable users to modify and recompile source code to their exact needs. It isn’t for the faint-hearted, and is reputed to be one of the hardest distros to master. 3 Ubuntu Studio For all you media enthusiasts out there, look no further than Ubuntu Studio. It comes with a plethora of media editing programs readily available to you, complete with workflows to help you manage your…

Intel has recently unveiled its latest venture into the world of the Internet of Things with the launch of its next generation Atom microprocessors. The Intel Atom E3900 has been meticulously designed from the ground up, with the company claiming it offers 1.7 times the computing power over previous versions of the processor. It can also support greater memory bandwidth and faster memory speeds, comparable to some of the higher-band chips currently on the market today. Ken Caviasca, VP of Intel’s Internet of Things group, said: “Built into a compact flip chip ball grid array (FCBGA) and featuring 14 nanometre silicon technology, the Intel Atom processor E3900 series is perfect for a wide range of IoT applications, where scalable performance, space and power are at a premium.” Arguably the most…

“For those who may not have seen VoCore2 before, could you tell us what the product actually is? In short, it is a small Linux computer that also boasts all the necessary tools to work as a smart router. For non-tech users, it can be used as a common router like other routers, just on a very portable scale. For advanced users, it can be used as a building block to connect external devices, such as a webcam, speaker, SD card and USB disk. All of these sorts of devices can expand and alter many of the VoCore2’s core functions and features. For avid developers, they can write code to it and control it to do pretty much anything, just like Arduino. And for business users, it is a Linux…

“Linus Torvalds announced the release of the Linux 4.9-rc2 kernel, noting that Linux 4.9 was “shaping up to be a big release”. This followed a 4.9-rc1 the week prior that had marked the end of the merge window for this cycle. Features that made it into 4.9 include support for memory protection keys (providing support for a new hardware feature introduced into contemporary Intel Skylake CPUs), the greybus subsystem that we covered previously, a new hardware latency tracer (based upon code originally written by this author), as well as the usual round of cleanups, bug fixes, architecture updates, shiny new drivers for various devices, and build and documentation updates (continuing the reworking of kernel docs from 4.8). Rumour has it that Greg Kroah-Hartman may make 4.9 an LTS or ‘Long…

Resources Linux Process Management: Commands You Should Know bit.ly/2eMgXO9 Process Management bit.ly/2edydeP How to Manage Processes from the Linux Terminal: 10 Commands You Need to Know bit.ly/2egkW2Y How to use ps, kill and nice to manage processes in Linux do.co/1kzo3hg Processes are a fundamental concept on any Linux operating system. When an executable program starts up, it runs a process and this process will be under the management of your Linux system’s process table. With the help of the available tools in Linux, you can view and change the processes running on a system. The ps and top commands are very powerful for viewing information about the running processes. Both these commands come with a variety of options that will enable you to view the process information the way you…

“Is there a chance that your productivity and efficiency could be improved, or do you just want your desktop to be more pleasing to the eye?” Perhaps you're a long-time Linux user; perhaps you recently switched from Windows. Whatever the case, while booting up your Linux computer daily, you might have become used to the desktop. It might do the job just fine – but is it really as functional as you need it to be? Is there a chance that your productivity and efficiency could be improved? Or do you just want your desktop to be more pleasing to the eye? Whatever the case, whatever your beef with the default look of your chosen distro's desktop environment, Linux is hugely customisable. The options are considerable, ranging from easily replacing…

The KDE Plasma Desktop is designed to be both attractive and easy to use, thereby encouraging productivity. But how can you install it on your current Linux PC? Two options are open to you. The first is to simply download and install one of the 12 distros that ship KDE software. With Linux Mint, Kubuntu, Debian, Fedora KDE, Archlinux and many more available (head to https://community.kde.org/ Distributions for the full list), you shouldn't have much trouble finding one suitable. KDE neon live-boots from the disc for you to explore immediately. Your second option is to install the KDE Plasma Desktop experience onto your existing (compatible) Linux PC or laptop. This will then sit alongside the pre-installed, default desktop environment. Each time you log in, you'll have a choice of desktop…

What you’ll need • Raspberry Pi 3 • Bluetooth USB dongle (if using an older Pi model) The Raspberry Pi model 3 saw the introduction of embedded Wi-Fi and Bluetooth capabilities. This now makes it even easier to interact with Bluetooth-enabled devices such as mobile phones, tablets and speakers. The Python programming language supports a range of libraries that enable you to interact, monitor and control various elements of a Bluetooth device. This tutorial combines the Pi’s Bluetooth hardware with Python code to create three simple but useful programs. First, build a short program to search for Bluetooth-enabled devices and return the 12-part address of each device. Once you have obtained the addresses, you can then scan and find Bluetooth services that are available on that particular device. Finally, use…

Sometimes, you simply need to interact directly with your remote server. You may register some catastrophic condition and you need to have a real person available to deal with the issue. Luckily, Paramiko includes a helper method that allows you to open an interactive shell session on the server. You can then send and receive data with the remote shell. The beginning of the code would look like: This newly created shell object can send and receive raw data to the remote shell instance. For example, you can get the load average with the following code. Because you are sending everything over this shell connection, you need to remember to add a newline character at the end of any commands that you are sending. Unlike other methods such as exec_…

If you gaze enviously at those hosting static blogs, while your server stutters through serving 5MB pages of CMS containing only a few hundred words of actual content, we think you may have overlooked something. Caching has been around for a while, from Squid proxies in institutional environments, designed as much for filtering, to your web server’s own caching capabilities. Varnish is different, an in-memory store of frequently requested pages and resources, letting Linux manage paging. Varnish arrives in your distro’s repository quickly, with good support for backporting to stable distro versions. Setup, beyond the defaults (such as changing the port and address you’re caching for in the default. vcl file), involves a dive into VCL – Varnish Configuration Language – but this makes configuration simpler than trying to shoe-horn…

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