Tabla de contenidos para No. 170 en Linux User & Developer

Whether you’re running Ubuntu and Fedora on a dual-boot system, or you’ve got a partition for Windows as well (you might even run a Hackintosh partition too), then you have a definite issue with your setup: rebooting. It can take time to reboot; from shutdown, to your GRUB 2 menu selection, and then booting into the chosen OS can take as long as 5-10 minutes – time better spent being productive rather than staring at a screen. When you consider the number of times that you need to swap operating systems purely to grab a single file, or input just one command, it’s all a bit clunky, really. With a virtual machine, however, you overcome this problem. The alternative operating system exists as software (a ‘guest OS’) that you can…

What we’ve shown you so far is really just the simple stuff when it comes to virtualisation in Linux. Whether you’re using VirtualBox, QEMU, KVM or any of the proprietary alternatives, virtualisation is a tool that works in many different ways, with a myriad of options for each operating system out there. For instance, we’ve alluded to the fact that ARM devices such as the Raspberry Pi can be virtualised using QEMU. Configuration and installation can be tricky, but it is possible, enabling you to install Raspbian and other Pi-centric distros on your desktop PC (although a lack of GPIO will limit the possibilities). Additionally, you may want to run a virtual machine based on Mac OS X. Remarkably, this is possible, and while it was previously limited to VMware…

Resources Tasker bit.ly/1i0IuDw IFTTT ifttt.com SL4A bit.ly/2byqjtf Busybox busybox.net/ Ulti Server bit.ly/19UzN8w TeamViewer QuickSupport bit.ly/1clagJQ IP Webcam bit.ly/1KqZpyq Kodi bit.ly/1G8mSQg joaomgcd bit.ly/2bcKHBu Vodafone Smart Prime 6 bit.ly/2aZeaer An Android phone makes a surprisingly good smart home server. Even a relatively old device will have a decent amount of storage, Wi-Fi connectivity, lots of sensors and, best of all, use a minimal amount of power. From a software perspective, Android is hugely flexible. As well as the option of using trigger/action-based applications such as Tasker, Android – with its Linux base – can use traditional command-line scripts. One of the benefits of building your own home automation system (so far as is possible) using a dedicated device is that you have a lot…

CMus bit.ly/2bSc9n9 Friends of the vi editor can use their well-liked syntax to perform media playback. Deploy CMus to get your hands on a nicely designed media player which behaves just like vim. People who dislike vim are unlikely to be happy with the product, though – if you don’t know vim by heart, another media player with a simpler user interface is likely to leave you happier in the end. mp3blaster mp3blaster.sourceforge.net If CMus is intended for vim heads, mp3blaster is the MP3 player ‘for the rest of us’. Its super-easy user interface is full of hints, which explain the various keyboard shortcuts needed for multimedia manipulation. The developer claims that its design was inspired by traditional CD-ROM players – if you ever handled a CD-ROM, you will not…

"You need to go to Google and enable the API beforehand" “For many people today, a major issue is keeping their time organised and keeping track of scheduled events. This gets compounded exponentially for every additional person that you need to keep track of. That includes children. This issue, we will look at how you can use a Raspberry Pi to display a family calendar and help you keep track of all of the events happening in the lives of your family members. Like the previous articles in this series, we will be focusing on the code you will need to get your calendar information. As for the actual physical display, there are many options you could choose. These include small HDMI displays or small screens that plug directly into…

Top 10 This month Stable releases (16) In development (10) Mint is definitely the flavour of the month currently, and it’s one of the few months we’ve encountered that we haven’t seen any major Ubuntu-based distro releases. Highlights Mint Mint has been steadily growing its userbase over the past few months, and it’s still gaining support thanks to its most recent update. Make sure to give it a download if you haven’t done so already. Elementary Elementary is one of the few distros to gain users this month, but we’re not surprised. It’s still one of the prettiest distributions out there, with some nice graphic enhancements also on board. Arch Arch may have fallen out of favour with people, but there’s some fantastic spin-off distros out there that look to…

Using the right tools for the job is just as important with virtualisation as it is with any other task. For instance, should you wish to virtualise an ARM device like the Raspberry Pi, VirtualBox will prove useless, as it is designed for 32-bit and 64-bit virtualisation. For ARM device virtualisation, you need QEMU, which is also capable of providing virtual machines for 32-bit and 64-bit platforms.This isn’t just about the Raspberry Pi, however, as almost any distro or operating system can be set up and run in QEMU – once you’ve mastered its command-line interface… 01 Install QEMU If it’s not installed already, update your Linux repos, before installing the QEMU package, using the command line. For Ubuntu, this will be: RedHat/Fedora users, go with: SUSE/openSUSE uses: If you’re…

“Given that Bash is Turing-complete, developers could – in theory – use ncurses or a similar library to create custom output” Resources Bash gnu.org/software/ bash Decades of hacker movies have ensured that Joe User has a dedicated bit of respect of all things Terminal. The Bash shell can be combined with a bunch of useful system commands to create nifty scripts dedicated to file system traversal. Given that Bash is Turing-complete, developers could – in theory – use ncurses or a similar library to create custom output. A more practical approach involves the invocation of dedicated programs that handle the selection process and return a result to the caller. As time went by, developers created a large variety of utilities that provide these features for you. Dialog is, by far,…

“Censys holds a huge amount of data that can be parsed by using its own search engine” Resources Zmap https://zmap.io/ Masscan http://bit.ly/1pSDGls Censys Database https://www.censys.io/ Censys API http://bit.ly/2bQpRVI Heartbleed bug http://heartbleed.com/ Heartbleed PoC exploit http://bit.ly/2bIKwMJ Scanning your network in search of well-known vulnerabilities is noisy and time-consuming. Although there are tools that can help you decrease the time it takes to scan an entire IPV4 network address space, such as Zmap and Masscan (covered in this tutorial), you should be aware of some freely available services that perform internet-wide scanning on a regular basis, exposing their results to anyone who cares to use them. This is precisely the case with Censys (see References). Censys holds a huge amount of data that can be parsed either by using its own search…

>_010 What’s in a name? Should you ever wonder about the role of a specific command, entering whatis followed by the name of the command in question tends to lead to further information on the topic. Our example, shown here, tells us what the gcc tool is all about. >_011 Simple help Most shell commands come with an integrated help system providing further information about the syntax. It can usually be accessed by passing in a parameter like -help, --help, -? or --?. If the syntax is not correct, the utility will usually show a little message informing you about the correct help parameter. Be aware that experimenting around with these commands can be dangerous: we would not try to find out the correct help parameter for rm or similar…

Given the tremendous power of the command line, developers and users might feel like controlling a computer remotely via a command line. This is made easy due to the relatively low resource demands – being text-based, streaming a command line works even over a throttled mobile connection. Initially, Unix workstations were accessed via Telnet. SSH – the abbreviation stands for ‘Secure SHell’ – is a more secure version of the protocol, which foregoes simple plain-text transfers for a more or less efficient form of encryption. Get connected Configuring the local SSH daemon depends from workstation to workstation: defer to Google to learn more. Connecting to an instance is really easy – the bickering about the host key can be ignored in most cases: Stay alive By tradition, a job started…

Each competitor will receive the standard race code, manufactured by the Formula Pi team, which has to be used within their robot. However, it’s up to the competitor to explore the ways they can adapt the code to help improve how their robot performs in a race. Essentially these changes can be as simple or as advanced as you see fit. For example, some may want to alter the code to help their robot react better when navigating corners, while others may want to improve how the robot makes decisions when going around the track. What we’re most impressed with is the control that each racer has over their robot’s motors. One particular section of the script relates solely to the motor speeds, and it’ll be up to the competitor…

Visual Studio Code provides embedded Git control for standard client actions. It also has built-in debugging support for the Node.js runtime Resources Fedorainstallation instructions for.NET Core microsoft.com/net/ core#fedora Visual Studio Code code.visualstudio.com C# Extension for Visual Studio Code code.visualstudio.com/docs/languages/csharp Microsoft has released an open source, modularised form of the .NET technology base called .NET Core that is cross-platform and offers support for a variety of Linux distros. The companion, .NET Core SDK, provides the command-line tooling to create simple .NET scaffold code, download project dependencies, compile, package and publish. However, to fulfil the story of .NET Core development on Linux, you need an editor that can support the iterative code-edit-debug cycle. Enter Visual Studio Code, a rich, cross-platform editor that is highly extensible, supports several programming languages, includes a debugger…

Resources A text editor such as Emacs or vi The Go compiler Concurrent programming is a difficult area of computing that requires special care and precision. This tutorial will talk about concurrent programming in Go, which introduces a unique approach to concurrency. Go uses goroutines and channels in order to program concurrent applications but can also support traditional concurrency techniques. Everything in Go is executed using goroutines; when a program starts its execution, its single goroutine automatically calls the main function in order to begin the actual execution of the program. This tutorial will mostly talk about goroutines and channels. However, Go also supports the traditional and well-known concurrency model that uses shared memory. The next tutorial is the Go series will continue talking about concurrent programming in Go so…

>_029 Who owns what? The first step to successfully managing the permissions of files involves finding out who has what rights. Entering ls -l provides you with an expanded version of the normal ls output which also lists owner and accessibility permissions in the form of a table similar to the one shown in the image. Above Each character describes one bit of file system information >_030 Understanding the output As long as the width of the terminal is wide enough to take the entire output, ls generates classic tabular output. The eleven characters on the very left of each line provide information on the rights. After that, the two usernames provide information about the user and the group owning the file: groups are a very efficient way of sharing…

The FriendFeed social media websitemayhavedisappeared beneath most peoples’ radars since Facebook bought it seven years ago, but its great legacy is the non-blocking Tornado Web framework. Designed to cope with thousands of simultaneous connections, its performance remains ahead of other Python frameworks like Django and it’s ideal for sites needing long-lived connections to users – perhaps for your customer support department’s new chat app? The HelloWorld app on GitHub is one of a number of demos which play to Tornado’s strengths and show you the possibilities from websockets to web spiders. Speaking of websockets, Tornado is just the thing if you’ve run up against the limitations of WSGI, which does not support non-blocking requests. Database support includes asynchronous drivers for MongoDB and PostgreSQL, and a choice of drivers for CouchDB.…