Linux FormatNovember 2018的目錄

Jonni Bidwell I had some bad habits when I was a student, one of which was computational group theory. They locked the lab at night, which is when I do my best (ahem, overdue – Ed) work, so I learned about SSH and forwarding X traffic and, eventually, installed Gentoo. The rest, as they say, is a rewarding role on a leading magazine for Linux enthusiasts! John Lane I’d been honing my unix-fu on an early Slackware for my day-job coding X/Motif front ends when I first saw Windows 95 and its increasingly familiar blue screen of death. I knew the world had changed enough for me to go out and buy a Linux CD set. I still have it somewhere… Nick Peers It was the perfect storm: more usable…

Valve, the company behind hit games like Half-Life, as well as the all-conquering Steam game store, continues to impress us with its forays into open source. First of all, eagle-eyed Michael Larabel of the Phoronix website spotted that Valve had created a Git repository (which you can visit at http://bit.ly/LXFValveGit) for its Moondust virtual reality technical demo. By creating a Git repository and starting to fill it with files, including an MIT licence, it looks like Valve could be open-sourcing the VR tech of Moondust, hopefully making it easier for developers to create virtual reality games and experiences. You can read Michael’s report at http://bit.ly/LXFMoondust. Meanwhile, GamingOnLinux has an illuminating interview with Philip Rebohle, developer of DXVK (http://bit.ly/LXFDXVK).DXVK is an open-source project that provides a Vulkan-based D3D11 and D3D10 implementation…

“This is my very first column with Linux Format. I’m one of a number of excited authors who have moved over from Linux User & Developer. I look forward to continuing my coverage of Linux kernel development and am grateful to Neil and the team for the opportunity. Please get in touch and let us know what you like (or don’t like) about the content. Most importantly, let us know what you’d like to see covered here! I’ve been using Linux for about 22 years, since beginning university studies in my early teenage years. I remember it taking two weeks to download Slackware 96 onto about 100 floppy disks as I only had “high speed” internet access once a week. It took two sets of disks as the first set…

“Oooh, four and a half years and over half a million words, and they finally give me my own column. So I’m just going to tell you about some Linux-themed activities of mine lately before the boss starts tapping the desk in an unsettling manner. I CAN RUN GTA V ON LINUX. I have dreamed of this day for five years. I saw other people were doing it with DXVK (before Proton was announced), but until recently I couldn’t make it work. The trick is to disable esync, spoof its video card detection, install some windows fonts and add a DLL override. Elementary. It may be unplayable because the mouse behaves like it’s stuck in a window, but don’t tread on my dreams. I also have the Steam Play-approved Nier:Automata…

Lenovo’s support of Linux on its laptops now includes a new BIOS update for its ThinkPad devices, which has an optimised sleep state for laptops running Linux. The fact that the world’s largest vendor of computers isn’t blocking Linux installs, but is instead openly supporting and improving its support of Linux is very welcome. The new feature was spotted by Twitter user @hdevalence (http://bit.ly/LXFLenovoBIOS),which shows a new BIOS option for a Linux Sleep State. According to the user, their ThinkPad X1C6 is running v1.30 of the ThinkPad BIOS. This can be installed with sudo fwupdmgr update .…

“So Linus has been taken to task over some of his responses on the Linux Kernel Mailing List. He’s apologised, and is taking steps to behave better in future. We can learn from this. This is about professionalism, which is an attitude of mind rather than anything to do with money. Managing Linux systems and associated software isn’t a straightforward task. If it was, most Linux support staff would be out of a job. Those of us who support users are there because we know more about the subject than those users do. However, I believe that too many support staff are disrespectful of their customers. There’s even been TV comedies based on that tenet. But they’re users, not “lusers”. They come to us seeking help, and we should be…

Send your thoughts to the Linux Format dungeon server at linuxformat@futurenet.com and secure your chance to win an amazing 32GB Nitrokey Storage 2! The Nitrokey is worth a cool €149, has 32GB of hardware-encrypted storage, supports hidden volumes, secures your online accounts with onetime passwords, can encrypt emails, files and hard drives and is an open source, open hardware solution. Protected with AES-256 and RSA keys up to 4,096! Learn more at www.nitrokey.com.…

FOSDEM 2019 The beautiful city of Brussels plays host to FOSDEM on 2-3 February 2019. It’s where open source projects big and small rub shoulders and share ideas, all working to produce the best software and products. At FOSDEM you can become accredited, attend workshops and talks, and take part in a series of fringe events. This event is awesome and attracts over 3,000 people each year. You’ll find more details at https://fosdem.org/2019. RASPBERRY JAM 7TH BIRTHDAY The Raspberry Pi’s seventh birthday is on 2-3 March 2019, and Raspberry Jams across the globe are invited to host a party celebrating the tiny computer. Children, adults, makers, crafters and hackers all get together to enjoy cake and share ideas. If you run a Jam or a Pi user group, then sign…

Q Could you explain or tell me how to speed up the start-up process, because since installing Mint 19 from your DVD it’s now taking quite a while to get to my browser page. Furthermore, the Internet connection takes much longer to start. It takes 30 seconds to reach the splash screen, then another 45 seconds for the panel to load, then 15 seconds for me to open a browser and access websites. John Jackson, via email A There was a bug with one of the Ubuntu kernel packages that caused a couple of services to stall while awaiting entropy, which could be the first issue you’re running into. You can often diagnose startup delays using systemd-analyze blame , which will tell you how long individual services take to load. The entropy…

Whether it’s still photography or a film recording some minutiae of the daily life for posterity, some people just have a natural knack for framing shots. They can make even a plastic bag blowing in the wind look mesmerising. With just a dash of creativity but far more patience, you too can transform your amateur captures into professional-grade videos, complete with a background score, if you like. But this is only possible if you’re willing to put in the time and effort it takes to master these behemoth, feature-rich projects. We’ve selected the tools that are easy to use for new users, yet offer enough features to be of interest to skilled video editors. With ever-decreasing prices of consumer hardware, it’s no surprise that these resource-intensive tools have continued to…

Video editing is resource-intensive work. As you grow accustomed to these tools and begin to work with it to process your home videos, you’re going to want to put their batch processing abilities to use, to save time. Although you don’t need oodles of disk space or RAM, you can’t get very far with these tools on low-spec machines. While you don’t need a dedicated high-end rig to get started with these tools, you can’t expect to go very far with a repurposed netbook, brought back to life with a lightweight Linux distribution. Kdenlive and Flowblade don’t provide minimum system requirements on their respective websites. This is perhaps because of their proxy editing feature. When enabled, proxy editing replaces your original clips with lower-resolution alternative. Because these low-spec proxy clips…

LXF: A while ago KMS came along, and that was exciting. Now I understand something else exciting called Atomic Modesetting has happened, but I don’t really understand what that is. DS: Originally, KMS was a lot of the display control layer from X just transplanted straight into the kernel. To be fair, it made things a lot better – it gave us hot-pluggable displays – but it was pretty creaky in a lot of places. One of the things it didn’t really do as well was overlay planes. If you’re on a normal 3D composited desktop where everything goes through your GPU so if you’re just playing Netflix, then you would be smashing your power by keeping this huge GPU active when all it’s doing is moving pixels around for…

Back when the idea of a decentralised social network was in its genesis (around 2009), a protocol family was designed that would cater to this brave new world. That family was called OStatus. OStatus defines protocols that permit de rigueur social networking activities: Atom feeds Users can publish feeds summarising their recent posts Activity streams A JSON-based format for encoding activity and event metadata, such as ‘liking’ a post WebSub Formerly PubSubHubbub (PuSH) a realtime notification protocol for streams, feeds and the like Salmon A message exchange protocol for unifying commentary on posts and articles. Provides a single comment thread where the same source is referenced in different places. So-called because salmon swim upstream. WebFinger A discovery protocol for entities identified by a URI. These may be people, in which…

Are you aged 19 or younger? Do you live in an ESA Member country – essentially most of Europe and Canada? Then your team can enter the Astro Pi Challenge’s Mission Space Lab, by sending your experiment idea to the ESA (European Space Agency) by the end of October 2018 – so you better get busy! The challenge is to design and code an experiment using the environmental sensors and cameras of the Astro Pi computers, called Ed and Izzy, which are on board the International Space Station. The competition offers two themes for experiments: Life in Space and Life on Earth. The latter uses Izzy fitted with a near-infrared cameras pointing at Earth. The Pi called Ed is for station-based experiments with its light-sensing camera. In this Phase 1…

OUR EXPERT Les Pounder is a freelance maker who works with organisations such as the Raspberry Pi Foundation to promote maker skills. He blogs at bigl.es As a learning tool, Minecraft is awesome. Kids play the game and learn how to create blocks of lava, diamond and water. But for younger players, the syntax of the commands is difficult. So for our project this issue we shall create an easy-to-use series of commands, cheekily called Minecraft Zero after GPIO and GUI Zero libraries, that enable kids to simply have fun, and learn a little Python along the way. On your Raspberry Pi, open the Python 3 editor, found in the Programming menu. Once opened, click File>New to create a new blank document. Now click File>Save and call the file mczero.py.…

As much as we can play with Python to improve the output of our weather station, there’s a lot to be said for at-a-glance personal forecasting. And if you’ve already dug up an DarkSky key, something like weeWX (weewx.com) is the perfect tool to get it done. Follow the install guide at www.weewx.com/docs/usersguide.htm to get it installed and started for the first time; once it’s up you’ll be able to access its interface via a local web page. WeeWX does support a vast number of sensors, although the default list is restricted by the drivers it includes. If it works with your weather gear, that’s great: you’ll be able to use weeWX to join in the swarm of user-run weather stations that contributes to WeatherUnderground’s vast forecasting network. If you’re…

OUR EXPERT Mike Bedford is always on the lookout for ways to do things differently. The third dimension is just one of his many photographic interests. We might live in a three-dimensional world but, by and large, our cameras are firmly rooted in two dimensions. Occasionally, a manufacturer will release a 3D model, which can be identified by its two or more lenses, but these are by no means cheap and, as a result, they rarely catch on. The fact is, though, that you can enter into the world of 3D photography with nothing more specialised or expensive than an ordinary camera, as we’re about to see. First, we’ll look at what we mean by 3D photography and describe, in general terms, how it works. Next we’ll provide practical instructions…

OUR EXPERT Dennis Jarecke is a passionate Linux enthusiast who’s been using Unix/Linux since the mid 1990s. Let’s face it. There’s always a shady organisation or overreaching government wanting to hack your system and spy on your life. Keeping your internet activity secure can be difficult, especially if you’ve got servers you want hidden from everyone except a few trusted individuals. That’s the point of what we’re going to do in this article. We’re going to show you how to access your own web server from anywhere in the world without anyone knowing about it. There are several ways you can create secure connections between two computers, but for our purposes we’re going to use OpenVPN. It’s considered one of the best solutions available because it’s based on sound encryption…

What happens when someone’s not behaving properly and you want to remove their access to your server? The easy-rsa program enables you to revoke their access. Here’s how you do it. The file /etc/easy-rsa/pki/index.txt is the “master database” of all your issued certificates. It will look something like this: A V indicates a valid certificate, and R means the certificate has been revoked. You’ll find the common name of the certificates at the very right. Let’s say that we want to remove Joe’s access. To revoke his certificate run the following commands: If you look in index.txt you’ll find there’s an R on Joe’s line. The easyrsa gen-crl command updates the certificate revocation list located in the file crl.pem. Now copy /etc/easy-rsa/pki/crl.pem to /etc/openvpn, add crl-verify /etc/openvpn/crl.pem to /etc/openvpn/server.conf, and…

The Linux kernel provides a page cache, an intermediary resting place for data travelling between applications and block devices, which is used for both reading and writing. The page cache improves read speeds – it enables the kernel to pre-fetch blocks and also makes repeated access to the same data much quicker. For writing, the page cache means that applications don’t have to wait for their data to be written to the block device – the kernel flushes writes to the block device when it’s convenient. It’s possible to request that the kernel avoids using its page cache. Opening a file using an O_DIRECT option means applications can bypass the page cache so their reads and writes happen directly between the block device and the application’s own internal buffers. In…

DESKTOP ENVIRONMENT Gnome Version: 3.30 Web: www.gnome.org Gnome is a popular desktop for Linux systems with more than 800 active developers behind it. Despite the fact that the Linux audience is split into supporters and opponents of the Gnome Shell’s design, there’s no doubt that this is the most actively developed desktop for Linux. Gnome is backed by Red Hat and Canonical, and enjoys wide adoption by Fedora and Ubuntu users, along with many other distros. The new Gnome 3.30 is an evolutionary release with a collection of small changes that enhance the overall user experience. Taking the latest version of Gnome for a spin is straightforward, because the official project web page suggests downloading demo ISOs that are based on Fedora Rawhide and openSUSE Tumbleweed. There are quite a…

Is FoundationDB suitable for storing your telephone contacts? Probably not, unless you’re BT and you have to deal with millions of records! However, FoundationDB has many other capabilities that make it a handy thing to have. Put simply, FoundationDB is a multi-model distributed NoSQL database with ACID support that organises its data as an ordered key-value store. It also supports replication and can be used by many programming languages. FoundationDB is suitable for storing structured data, time series data, large values and binary large objects. However, what makes FoundationDB unique is that it maintains a consistent state in a distributed system and is easy to install and configure, and can be scaled to meet your particular requirements. Additionally, FoundationDB can easily handle heavy loads and so it’s suitable for busy…

Basic web coding skills like HTML and Javascript can be transferred into the construction process for an Android app. Although there are many more files than a web app, the actual functionality of an app can reside in just one or two files. When apps are submitted to Google Play, they’ll have a version number. Thus, if we add a newer version at a later date that’s built from the first version, we must change the version to a higher number. If the coding in a Cordova app is lightweight, then this will result in excellent performance on a user’s phone. We can present any text and imagery on our app, and display external web pages, too.…

FOR THE OLDER PC Peppermint OS 9 32-bit Ease of use is the watchword this month and the first distro that fits into that category is Peppermint OS. This distro uses Ubuntu as a starting point, but ends up quite a way from a normal Ubuntu experience. This is a fast and lightweight distro using the LXDE desktop, although its developers are quite happy to cherry pick elements from other desktops, such as the use of the Nemo file manager from Cinnamon for its handling of network shares. It also uses the window manager from XFCE. It sounds like a bit of a hotch-potch, but the Peppermint devs have worked at making everything work together smoothly, giving a unique desktop experience. Peppermint OS is described as a “web-centric” distro. This…

Advanced Bash Scripting Guide Go further with shell scripting. Bash Guide for Beginners Get to grips with the basics of Bash scripting. Bourne Shell Scripting First steps in shell scripting. The Cathedral and the Bazaar Eric S Raymond’s classic text explains the advantages of open development. The Debian Book Essential guide for sysadmins. Dive Into Python Everything you need to know. Introduction to Linux A handy guide full of pointers for new Linux users. Linux Dictionary The A-Z of everything to do with Linux. Linux Kernel in a Nutshell An introduction to the kernel written by master hacker Greg Kroah-Hartman. The Linux System Administrator’s Guide Take control of your system. Tools Summary Overview of GNU tools. GNU Emacs Manual Six hundred pages of essential information! Producing Open Source Software Everything…

I say it every year (probably) that there’s never been a better time to get into Linux. It’s never been easier to use, there have never been so many features, it’s never been so smooth to install, it’s never been so much fun – and you hold in your hands the best guide to getting Linux up and running on your PC. For the 2018 Escape Windows guide we’re going with Linux Mint 19. Any Windows user is going to feel right at home with this version of Linux thanks to its classic Cinnamon desktop: it is so fast, so straightforward, so easy to update and offers so many features from its Software Centre. So go dive in on page 34 now! For those new to Linux we show you…

Google has a contentious history when it comes to patent applications, and its latest move to patent asymmetric numeral systems (ANS), a widely used data compression algorithm, has attracted a fresh round of criticism. This is mainly due to the developer of ANS, Jarek Duda, who had published his work with the intent that it was for the public domain and free of restrictions. In an Ars Technica article that goes into the specifics about Google’s patent application and Duda’s objections over it (http://bit.ly/LXFANSGoogle), Jarek claims that the technique Google’s trying to patent was suggested by himself in an email exchange in 2014, a claim that a preliminary ruling in February by European patent authorities agrees with. The US Patent Office has now issued a non-final rejection of Google’s application…

Greg Kroah-Hartman announced the release of Linux 4.19-rc6, having stepped in temporarily while Linus takes some time off for personal reflection. In his announcement, he noted that, “It all just works on my systems, and I have not heard of any major outstanding issues as of this point in time.” Indeed, by all accounts, Greg has done an outstanding job, which isn’t surprising when one considers that he’s used to maintaining the -stable kernel trees relied upon by many. #MeToo The Linux kernel community had an overdue appointment with reality this month. It began with a message from Linus Torvalds titled “Linux 4.19-rc4 released, an apology, and a maintainership note”, and would end with a high-profile story in The New Yorker magazine in which several well-known developers would accuse him…

“The Video4Linux subsystem (V4L) has been the default programming interface for media developers, most notably for video capture devices, but also for encoder, decoders and streaming video output devices. Unfortunately, for most of its existence, V4L has fallen behind in support from vendors. However, over the past few years more vendors have begun contributing to the upstream kernel community, including to the V4L framework. New features are happening to enable it to support the features that new hardware requires. This is the case of the Request API, which is meant to support lower-level codec hardware, the new generation of cameras such as those that are now standard in smartphones, and the experimental explicit synchronisation API, which reduces latency and improves efficiency while providing a simpler interface. With such enhancements being…

After the news of Linus Torvalds stepping away from Linux, as well as a new Code of Conduct being implemented, some people have been wondering what would happen if they took their code out of the Linux kernel and rescind the licence grant. According to a developer who claims to be a lawyer, you’ve not signed away ownership of your code and “Gratuitous licenses are revocable at will”. These claims come in a rambling and at times rather offensive message, but it raised questions in the community about what rights you have to remove your code and revoke the GPL licence. However, an in-depth article from 2008 (http://bit.ly/LXFGPLLaw) explains in detail how and why the GPL v2 licence is irrevocable. While some contributors may be concerned that they’ll lose their…

Subscriber or not? I was confused to receive your “recently unsubscribed” newsletter as actually, I had not unsubscribed and I wasn’t aware that my subscription had expired. I had in fact only recently renewed my subscription for another two years! But I’m a little bewildered, because I also received by snail mail a letter informing me that Linux User & Developer magazine will no longer be published and that the remainder of my subscription will be transferred to Linux Format. I’m unsure of the number of issues left of LU&D. Truls, via email Neil says Accept my apologies for any confusion. As you’ve noticed, these subscriber newsletters are fired out from our marketing team, so I suspect there’s a small window of potential confusion between them building mailing lists of…

The small print  Q I’ve just used the LXF240 DVD to install Mint 19 (Tara) on several computers and as a result I have a couple of questions: First, I used both the DVD and a downloaded Mint 19 ISO to install Tara on several computers and I experienced the same problem in all cases. So the problem is not with your DVD, but with the Mint ISO itself. The problem is that my HP Laserjet 1102w would not work under Tara. It worked fine under Mint 18.x and 17.x, though. I also used your LXF239 DVD to install Ubuntu 18.04 (Bionic), on which Mint 19 is based, to the same set of computers. My HP 1102w worked fine in all cases using that DVD. I finally fixed the problem with…

We’d love to try and answer any questions you send to lxf.answers@futurenet.com, no matter what the level. We’ve all been stuck before, so don’t be shy. However, we’re only human (although many suspect Jonni is a robot), so it’s important that you include as much information as you can. If something works on one distro but not another, then tell us. If you get an error message, please tell us the exact message and precisely what you did to invoke it. If you have, or suspect, a hardware problem, let us know about the hardware. Consider installing hardinfo or lshw. These programs list the hardware on your machine, so send us their output. If you’re unwilling, or unable, to install these, run the following commands in a root terminal and…

We’re running the latest offering for each of the tools featured in this Roundupon top of a quad-core machine with 12GB RAM. Apart from vast amounts of RAM and processing power for optimum performance, you’d also need plenty of spare disk space to horse around with video editors. All the projects are fairly popular and many distribution feature them in the software repositories. Some of the tools featured here also ship Snap and AppImage packages for easy installation. Apart from ease of installation, documentation is vastly important to help new users acclimatise to the vast feature set contained within each of these projects. We’ll discuss some of the most useful features these tools offer and whether their interface is intuitive or if it gets in the way of you jazzing…

Whatever their interface and design philosophy, all video editors perform similar function. To begin, the tools enable you to manipulate a single video file, or a series of them, and arrange them into a sequence. All along, you can deploy different effects to smoothly transition from one clip to the next. You can also insert a title to the video, to give it proper introduction. In common parlance, a track comprises video clips, effects and title file. The tools make it possible to work in parallel on several different tracks, where one is for audio, another for effects, and so on. The tracks are all visible on a single interface referred to as the timeline. The final part of working with these editors is rendering, which turns your work into…

A quick look at the Wikipedia page for video editors will reveal close to a dozen active open source applications. Couple this with all the freeware offerings and you get a sizeable number of alternatives to choose from. Cinelerra is a professional-grade editor that’s complex for absolute beginners. Avidemux is fairly straightforward to use, but only provides basic functionality. It’s also not as actively developed as the tools featured in this Roundup. While we’ve focused on the more established applications in this Roundup, Natron is a viable alternative. First released in 2014, its interface is influenced by commercial professional-grade software such as BlackMagic Fusion and Nuke. Although it hasn’t seen a new release since 2016, Pitivi is another alternative. Available as a Flatpak package, the application was once tightly integrated…

We’ve focused on Mastodon here, but there are all kinds of other open source, decentralised alternatives to popular social media platforms. PeerTube is a video-sharing platform that uses WebTorrent technology to ease the burden on servers (again, anyone can host a server and servers can federate with each other). When a user views a video they also share it with other users, creating a sort of positive feedback loop for popular videos. For static images, and those looking for a home for them that isn’t Instagram or Flickr, there’s PixelFed (https://pixelfed.org). Like Mastodon you can host your own Pixelfed instance and federate with other instances, such as the one you’ll find at https://pixelfed.social. For a more Facebook, less Twitter, type of decentralised social network, diaspora* (https://diasporafoundation.org) is where you should…

My adventure into the wonderful world of coding and programming started in 2012 with the launch of Raspberry Pi 1 Model B. I knew very little about coding apart from the occasional PIC-AXE electronic projects or Flowol charts. I had also at the time jailbroken my iPhone to reveal the open source core in the operating system, so when I saw the Raspberry Pi launch with Debian as an operating system I knew instantly I wanted one. To say that I was a “n00b” in programming terms is an understatement, but the promise of hooking electronics and peripherals up to the 26 GPIO pins was the ultimate incentive to learn – fast. However, every single board was snapped up in less than a fortnight and so the only chance to…

Our mczero.py code can be used via the shell, for an interactive battle of skill against other players. But it can also be used as part of a project in the same manner as we import other libraries of code, for example when we import the Minecraft (mcpi) library into our mczero.py code. To do this we need to ensure that any code that we create is saved in the same directory as the mczero.py file. To start we import the mczero library: Then we can use any of the functions in our code by calling their names, preceded by the name of the library, in this case mczero. For example let’s pop a message in the chat window: Then let’s create a loop for our fire_feet function: Any code…

OUR EXPERT Shashank Sharma is a trial lawyer in Delhi and avid Arch Linux user. He’s always on the lookout for geeky toys. Originally released in 2004 under the BSD license, Calcurse features a Ncuses-driven interface. It can be used to keep track of all your appointments and tasks list. If you’re someone who’s fond of working with the keyboard, Calcurse is a fun, productive tool designed especially for you. The project doesn’t ship pre-compiled binaries itself so you must install it from source if it isn’t offered in the software repositories of your distribution. Download the source tarball from the project’s website and uncompress it with the tar zxvf calcurse-4.3.0.tar.gz command. Read the INSTALL file within to confirm if all the dependencies are installed on your machine. If you’re…

Stereo photography can provide some impressive results but it’s not the ultimate in 3D photography because there are other depth clues that we rely on that are not reproduced. There is one imaging technique, however, that replicates every depth clue. Included here, for example, is motional parallax. This enables the viewer to move their head and, in so doing, see parts of a scene that were previously obscured by closer objects. Not only this, but it also means the viewer can selectively focus on objects at different distances. The method is called holography and, although holograms have been produced on old-fashioned photographic films or plates for over 50 years, digital holography is still in its infancy. Some facts and figures will give an inkling of why a digital holographic camera…

The default cipher for OpenVPN is BF-CBC., but it’s no longer recommended because of known attack vectors against it. Change it to something more secure like AES-256-CBC. The Electronic Frontier Foundation has a good article on encrypting files with PGP ( http://bit.ly/2KP3g0O ).Just remember to put a long password on to your private key. Getting all the networking stuff configured is the hard part about OpenVPN. If you’re having problems, take down the firewall and get OpenVPN working without it. Then turn the firewall back on.…

OUR EXPERT John Lane is a freelance Linux expert for whom spinning disks is the source of much amusement. Linux users are blessed with a plethora of storage options beyond those selected by the typical installer. Reviews abound on what’s available: the latest SSD or hard drive, choices of file system, the pros and cons of encryption. But how do the options compare, and how can you test your own system before stepping off the well-trodden ext4 path? In this tutorial we’ll compare several filesystems, from the de-facto standard ext4 through alternatives such as XFS, IFS and the ill-fated Reiserfs. We’ll include those Microsoft filesystems we can’t avoid encountering with NTFS and vfat, and also test the oft-called next-gen offerings that are Btrfs and ZFS. We’ll run some tests using…

OUR EXPERT Dr Sinitsyn is a cloud infrastructure developer at Yandex by day, an open source contributor by night, with interest in everything from AH to X509. Over the past 27 years, Linux has seen many reincarnations of the “universal package manager”. Some attempts such as Autopackage are already history. Other are still alive, but nevertheless struggle to provide a viable alternative to RPM, Deb and friends. Docker and other container engines made universal packages for services a reality yet gave little-to-no support for desktop applications. But there are ongoing efforts to rectify the situation. One is Snappy, a Ubuntu thing which we touched briefly in LXF242. Another is Fedora-baked Flatpack, which has recently released a 1.0 version. This is a milestone that marks both feature completeness and readiness for…

Imagine it’s 2005 again. There are many Linux computers connected to the Internet all over the world, and most of them are underutilised. Why not donate or sell their spare CPU cycles? However, this means running a third-party code on your precious machine, so security is a great concern. That was the idea behind the CPUshare project (http://caca.zoy.org/wiki/CPUShare), an early compute cloud attempt. Secure computing, or seccomp, was this cloud’s security mechanism. Once enabled, it restricted certain processes with four syscalls: read(2) , write(2) , _exit(2) and sigreturn(2) . CPUshare project wasn’t a great success, yet seccomp has remained part of the Linux kernel since version 2.6.12. Some years later, Google saw its potential to sandbox browser plug-ins. Four syscalls seemed too strict for this type of software, so another…

The manner in which FoundationDB deals with backup and restore is a little unusual. First, a FoundationDB database can be backed up to local disks, which is the usual case with most database servers, a blob store or to another FoundationDB database. The latter type of backup is called Database Recovery (DR) in FoundationDB terminology. The backup_agent server process, which is responsible for the backup process, starts automatically on each FoundationDB instance. We’re going to back up a local FoundationDB instance. The general format of the Backup URL is file://</absolute/path/to/base_dir>. Because these paths are absolute, you’ll end up having a Backup URL with three slash characters, such as file:///home/tsoukalos. You can define your own tags using the -t command line option. Using the previous backup for restoring your data is…

The easiest way to sign the APK with apksigner is to have one terminal open the Android directory and another in the /apk directory. This is because we must be in the Android folder to run a command and we need to be in the /apk folder to run other commands on the apk files. Note that we’ll need to use an Android SDK build tool above version 24.0.3, which come with apksigner. When signing an apk, make a .jks file using the keytool command: Here’s what happens with the following commands. The first one creates an unsigned release apk file. The zipalign command will copy and align the file you just made. The third command does the heavy duty work and completes the process:…

One of the first problems someone interested in learning to program encounters is picking a language. They’ll get advice from all sides on why they should start with Perl or Python, C or C++, and that’s before you get into all the other languages: Java, Go and Haskell, for example. In truth, the core principles of programming apply to all languages and much of the knowledge gained when learning in one language is still useful when trying another. But that still leaves the stumbling block of where to start. This is another area in which the humble Raspberry Pi has helped. The Raspberry Pi was aimed at getting people to use and program computers, because it was cheap. Kids could have their own and it didn’t matter if they broke…

Office tools There’s more to life than LibreOffice. We explore the options for editing your documents, drawing graphs and much more. The smallest server They might be small but they remain mighty… a compact web sever can still get your pages served for the world to see. Build your own electronics Grab your soldering iron, because it’s time to start designing and making your own PCBs for fun and profit! Cave surveying Pop on your hard hat, grab your laser measure and get ready for some spelunking, as we go map some caverns. Contents of future issues subject to change – we might still be having an existential crisis.…

Linus Torvalds has announced he’s taking a break from his work as a maintainer to address what he calls his “unprofessional” behaviour. In his release announcement for Linux 4.19 release candidate 4 (http://bit.ly/LXFLinux419RC4), Linus explains the reasons. “I’m not an emotionally empathetic kind of person and that probably doesn’t come as a big surprise to anybody. Least of all me,” he says. “The fact that I then misread people and don’t realise (for years) how badly I’ve judged a situation and contributed to an unprofessional environment is not good.” Linus has long been known for his outspoken and sometimes combative nature, but a few recent incidents have brought things to a head. The Maintainer Summit (http://bit.ly/LXFMaintainer2018), an annual invite-only gathering of kernel developers to discuss issues with Linus, was rescheduled…

“The Linux Foundation recently partnered with Heavy Reading to conduct a survey to gauge industry perceptions of open source across networking technologies. Key findings indicate CSPs show an high level of sophistication around new technologies and approaches. Ninety eight per cent of CSPs are confident that open networking solutions can achieve the same level of performance as traditional networking solutions, and 69 per cent are already using open source networking solutions in production networks. SDN in particular is seeing strong deployment, with nearly 60 per cent of CSPs reporting they have either already deployed SDN (39 per cent), or are currently trialling SDN (20 per cent). The survey shows open source has become core to how service providers are reinventing their networks and basic assumptions on how networks are managed…

Jiri Kosina posted a patch series titled “Harden spectrev2 userspace-userspace protection”, which seeks to improve the speculative execution side-channel mitigations in upstream (non-vendor) kernels against Spectre-v2. As a reminder, Spectre-v2 concerns the “branch predictor” hardware within a processor that seeks to guess which parts of the kernel code will run next based upon previous behaviour. This hardware can be “trained” by a malicious program to influence another, causing it to deliberately guess wrongly and pull data into the CPU caches during speculative execution of future code. This can then be extracted through a side-channel technique. While the upstream kernel includes support for a special “IBPB” (indirect branch predictor barrier) processor operation to flush predictors on process switches, it didn’t contain protection against two threads running on the same core attacking…

ROBOLINUX 10.1 The latest version of this Ubuntu-based distro brings a range of new package updates, and is supported until 2023. It’s built on Ubuntu 18.04 and is available in Cinnamon, MATE and Xfce editions. The most recent versions of Firefox, Thunderbird, Open VPN, GParted, LibreOffice and more are included. For a full rundown of the new features, visit the downloads page at: https://robolinux.org/downloads. KDE NEON 20180925 By the time you read this, the newest version of KDE neon will have been released. This is a distro based on Ubuntu (18.04 in this case), and is designed to provide the cutting-edge KDE Plasma desktop. According to the release statement (which can be read at http://bit.ly/LXFKDEneon), “Our packages are built on the latest Ubuntu LTS edition and today we have moved…

Successful escape I have been using Linux for about 10 years now. I work in IT and use Windows, macOS, Linux (all forms from Ubuntu, Mint, to XenServer, Kali, Raspberry Pi’s and more). I’m not writing to say I’m this super Linux geek, not by any means. About two years ago I had a client who needed an upgrade to his business PC. His list of demands: something that doesn’t crash so often or gets infected so easily. I showcased Linux and explained the software he would be able to use to run his business and save some mullah! He was intrigued and admitted that he had heard of Linux but thought that it was for more technical users. He decided to take a chance because he was tired of…

Alpinux, le LUG de Savoie Meets on the first and third Thursday of the month at the Maison des Associations de Chambéry, France. www.alpinux.org Build Brighton Thursday evenings is open night. www.buildbrighton.com Cornwall Tech Jam Second Saturday of the month alternating between Bodmin and Camborne. www.cornwalltechjam.uk Huddersfield Raspberry Jam Meet every month at Huddersfield Library, typically on the fourth Saturday of each month. https://huddersfieldraspberryjam.co.uk Horsham Raspberry Jam Park side, Chart Way, Horsham. www.facebook.com/hackhorsham Leeds Hackspace Open night every Tuesday 7pm-late, Open day second Saturday of the month, 11am-4pm. www.leedshackspace.org.uk Medway Makers 12 Dunlin Drive, St Mary’s Island, Chatham ME2 3JE. www.medwaymakers.com rLab Reading Hackspace Unit C1, Weldale ST, Reading, Open Sessions Wednesday from 7pm http://rlab.org.uk Glasgow Makers and Hardware Hackers Mitchell Library, Glasgow. https://m.facebook.com/groups/115303729096198…

Q I Format ’ve been for subscribing over 12 to Linux now years and it’s been a fascinating journey. Your recent innovation of sending email newsletters to subscribers helps me keep up to speed. I’ve bought a new desktop PC and installed Linux Mint 19. I use LibreOffice Writer and need to display two documents side by side, so I can copy and paste text across from one document to the other. In Windows I right-click at the bottom of the screen and a box offers various options, including Show windows side by side. This enables me to display two documents at the same time. How can I get the same result in Linux, using LibreOffice Writer? I’ve looked at help forums online that claim there’s a bug in LibreOffice,…

At the very least, the video editor should be able to work with a variety of file formats and produce output files that are fit for appearing on different platforms, such as online publishing. Thanks to their reliance on FFmpeg, most of the tools on our list can work with almost any video format, and render files in your desired format. All the tools present a large scrollable list of formats you can export files your project to, after you’re done editing the videos. With Flowbladeand others, you can also create a profile of the project, which depends on the source video files you wish to work on. All the tools are capable of correctly identifying the source of the files, and will suggest changing the profile if it’s different…

By the time you read this, Microsoft will have rolled out another major Windows 10 update on to its user base. These days you’ve barely had time to get used to one set of changes (whether it’s features being added, taken away or simply moved with no explanation) before more are incoming. There comes a point when you say enough is enough, but what’s the alternative? It’s Linux of course, but some would say that’s a complicated and difficult substitute in itself. The answer is no, and as proof we offer up this article to show you how easy it is to get started with Linux. We’ve carefully picked a flavour – delicious Mint – that’s specifically designed to appeal to Windows switchers. Linux Mint is based on Ubuntu, which…

Collabora’s Daniel Stone has spent nearly two decades hacking on the Linux graphics stack. A term that would send lesser men mad. But not Daniel. We caught up with the guru of pixel pushing in hip and tech-culture-steeped Shoreditch to talk Wayland, Atomic Modesetting and virtual reality. And to reminisce about sunny Melbourne. Linux Format: So they tell me you’ve been working on the Linux graphics stack for quite some time? Daniel Stone: Yeah, I think I’ve been doing that for about 16 or 17 years now. I started out doing packages for Debian, and ended up at one of the colleges at Melbourne Uni. They needed a newer version of XFree86, so they asked me to arrange it. “How hard can this possibly be?”, I thought, and I just…

We mentioned earlier not being able to search for individuals by name. This is a deliberate measure designed to reduce harassment, protect privacy and generally make the Mastodon fediverse a more wholesome place than the birdsite ( oh, look at you all down with the lingo – Ed). In fact, a Mastodon instance is only searchable through the use of hashtags, so if you want your toot to be found you’ll need to, in the immortal words of UK Home Secretary Amber Rudd, understand the necessary hashtags. Mastodon communities may be more or less tolerant of certain kinds of speech, but instances hosting (potentially) offensive content can be blocked or silenced by other instances. Other key differences to Twitter include a 500-character limit on toots, so that discussions can be…

Professor Tim Berners-Lee invented the World Wide Web, so when he announces that his invention “has evolved into an engine of inequity and division” (see https://medium.com/@timberners_lee/onesmall-step-for-the-web-87f92217d085), people tend to listen. The professor and his team at MIT have come up with a plan to re-invent it. Built on top of the existing web, the Solid platform hopes to give users the ability to choose where their data is stored, who can see it and how it is used. Solid is a portmanteau of “Social Linked Data”, and the idea of linked data is nothing new – Berners-Lee introduced it in 2006, alongside the idea of the semantic web. It enables published data to be contextually linked and sourced from external sources, so that it’s no longer beholden to a particular…

OUR EXPERT Alex Cox is a tech expert and writer, inexorably drawn to tinkering with, and inevitably breaking, anything put in front of him. Weather, eh? Who’d have it? Whether it is the relentless onslaught of that burning gasball in the sky or the incessant gushing of the rain, weather never ends – and not only does that make it the perfect topic of conversation with half-acquaintances (editors?–Ed) and family members, it makes for a great project: using Linux shenanigans and fancy sensors to feed your obsession with meteorology the right way. A few issues ago (LXF238), we looked at the MakerLife Weather Station kit. The fact that we have one hanging around means we’re making it (and its Pi Zero W, and included sensors) at least the initial basis…

When you first run Calcurse, it will create a ~/.calcurse directory. All the notes you add to an appointment or task are stored as separate text files within the ‘notes’ sub-directory. The apts and the todo are plain text files that contain respectively all the appointments and TODO entries. The keys file contains all the user-defined key bindings for using Calcurse. As the name suggests, the conf file contains all the configuration settings for Calcurse. You can tweak Calcurse from within its graphical interface itself, by pressing C. The configuration options are split into six different categories: General, Layout, Sidebar, Colour, Notify and Keys. The tool offers the choice of eight different layouts, which govern the placement of the panels within the graphical interface. You can similarly choose a different…

In taking stereo pairs with an ordinary camera, we end up with two files per stereo pair in an ordinary file format such as JPG. However, there are file formats that enable a single stereo pair to be stored as a single file. Dedicated 3D cameras have tended to use one of these stereo file formats, and you might choose to convert your ordinary Jpegs into a stereo format to reduce the number of files you have to keep track of. Some TVs can display these images, too. The two of the most widespread file types are JPS (Jpeg Stereo) and MPO (Multiple Picture Object). A JPS file is nothing more than a JPG file with the two images displayed side-by-side. You’ll see this if you rename a JPS file…

First, designate an unused IP address in the 10.0.0.0/24 range you want to be attached to your second site. Let’s say it’s 10.0.0.222 for demonstration purposes. Next, create a virtual host file for the new site in /etc/apache2/vhosts.d. In it we designate <VirtualHost 10.0.0.222:80> so Apache responds to that IP address. Restart Apache with systemctl restart httpd . Finally, add 10.0.0.222 to the tun0 interface by running ip address add 10.0.0.222 dev tun0 . This will attach the IP address to tun0 so the device responds to it. Verify it’s added with ip address show . Change your after.local command to openvpn --config /etc/openvpn/server.conf && sleep 10s && ip address add 10.0.0.222 dev tun0 so it’s executed on a reboot. The &&’s make sure the previous command runs properly before…

An I/O operation is the reading or writing of an amount of data, anything from a single byte up to a limit imposed on the target device by the kernel. You can view this by looking at /sys/class/block/sd<X>/queue/max_sectors_kb. This limit may be changed but is subject to the hard limit presented in /sys/class/block/sd<X>/queue/max_hw_sectors_kb. A single system call such as a read or write operation for a larger amount than this limit would result in the kernel performing multiple I/O operations and its ability to perform those is what we measure as IOPS.…

The history of computing is the history of abstractions. CPU microcode abstracts logic gates, assembler abstracts microcode, and C abstracts architecture-specific assembler. Interpreted languages such as Python abstracts silicon CPUs, web applications abstract whole operation systems. This list can be continued, but you’ve got the point. Twenty-five years ago, programming was closer to hardware. You used inline Assembler to disable the blinking cursor. You wrote to video memory to draw shadows beneath your text-mode dialogs. Since then, the state of things in computing has changed drastically. Most modern programs rely on runtimes so their authors can concentrate on application logic rather than memory management. The kernel is buried inside these layers of abstractions. Maybe you find learning its nuts and bolts fun, maybe not. Either case, is there any sense…

In a nutshell, process tracing is a mechanism for one process (which we call a tracer) to have complete control over another process: a tracee. With great power comes great responsibility, and ptrace can vastly affect security if implemented improperly. In a nutshell, you don’t want ptrace to be a mechanism to reveal more information than the user invoking it could normally see. Intuitively, this means an ordinary user should be able to trace its own processes; root should be able to trace everything. This is in fact very close description of the default algorithm the kernel uses for ptrace access mode checks when no special Linux Security Modules (LSM) are loaded. In fact, privileged access is enabled if the calling process has CAP_SYS_PTRACE capability. By the way, this means…

This month’s tutorial will cover the usage of NetBeans to build Android apps. Alongside NetBeans, we’ll also look at a few basic commands that can be run from a terminal to create, troubleshoot and build Android apps. Although this tutorial will focus on NetBeans, any other text editor could also be used to edit the code and the terminal could be used to create, build, troubleshoot and make signed APKs to submit to Google Play. By the end of this article we’ll have a lean footprint for building Android apps and could literally set up any Ubuntu box within 20 minutes to achieve our end goal. So, let’s get started and dive into our setups and installations to acquire such goals. Know your beans NetBeans has editors for various coding…

When we build Android apps, we have options to create pre-built templates using our libraries such as Jquery Mobile. In short, this enables us to create an elegant menu that can be edited to suit our needs. In many cases, all we need to do is swap in text and add or delete more buttons. With that said, let’s do a jquery mobile app: Then we use the cordova create command followed by the folder name we want for the project, followed by a few more commands: When prompted Would you like to add jQuery mobile... we type Y and hit Enter. After that, we’ll be asked what to do. Select applyTemplate. After that, we choose listView. Then, we type Y to keep the code. That’s it. Like the previous…