Linux FormatSeptember 2019的目錄

“Open source is about community: the belief that, between us, we can make better software so that more people can benefit. That might seem at odds with a commercial company, which exists to make a profit and provide value to its shareholders, but it doesn’t have to be. Open source software is ideal for charities. The website is an obvious example, but Linux plus LibreOffice, Thunderbird and Firefox covers most, if not all, of the functionality required at the desktop. ‘Charity’ doesn’t have to be a household name. There will be lots of local charities near you that would welcome some help, be they homeless centres, support for older or disabled people, or even your local amateur drama group. As a reader of LXF, you have skills those charities could…

“Many of us who began using Linux in the early days did so through distributions that shipped on one or (usually many) floppy disks. My very first Linux distro came on 200 floppies, each of which I wrote after downloading a disk image over a (‘high speed’) 100Kbps internet connection I had access to once per week. It was with some nostalgic sadness, then, that floppy support appeared to reach the end of the road in Linux 5.3, with Jiri Kosina marking it as ‘orphaned’ (see page 8). In case you never had the pleasure, floppies were a low-cost storage medium commonly used until the turn of the century in which data was stored on a flexible (‘floppy’) plasticated magnetic disk, housed within a sleeve of soft or hardened plastic.…

Q Lost in Orbit I run Slackware 14.2. My very old and favourite Logitech trackball died of old age, and I’ve replaced it with a Kensington Orbit trackball: two buttons (left 1, right 3), a ball to move the cursor and a ring as a horizontal scroll wheel. I cannot paste highlighted text as the two buttons simultaneously do not function as button 2. I’ve checked the buttons using xev and xinput, and need an appropriate section for /usr/share/X11/xorg.conf.d/10-evdev.conf. Brody Jones A I too had a Logitech trackball. Mine too died after a few years. I also replaced mine with a Kensington Orbit trackball, so I have some idea of what you are going through. As you indicate, it is normal to press both buttons at once to simulate a…

Arduino boards are quite unlike most other SBCs because they don’t run an operating system or drive a display. This is because they’re intended for embedded applications – a piece of equipment where the user might not be aware that a computer is buried inside, working in the background – where these are would be an unnecessary overhead. The result is that they can use very cheap processors to good effect. For example, the ATmega32U4 that’s used in the Arduino Leonardo, and also in the LattePanda to provide compatibility, has an 8-bit architecture and is clocked at just 16MHz. As a microcontroller it also has its own memory and flash storage on chip and these are also extremely modest: just 2.5KB and 32KB, respectively. Because of this, software is usually…

Atom, Emacs and nano have a user manual; with Brackets you’re limited to a Getting Started project that opens when you first use it, and a Quick Start guide. All except FocusWriter have either a user forum or mailing list for support. It would be easy to argue that FocusWriter doesn’t need a manual or user support because it’s so simplistic. There’s always more than an element of truth to the suggestion that ease of use is inversely proportional to functionality – and that’s true of our group of text editors. Both FocusWriter and to a lesser extent nano are so simple to get up to speed with because of their limited set of features. Even though nano is keystroke-driven, the common commands are listed at the bottom of the…

We’re still patiently waiting for the year of the Linux desktop, but one sign that Linux has become mainstream is that it is now actively targeted by malware pushers. Perhaps not to the same extent as Windows, and perhaps those miscreants are more interested in hijacking servers than desktops, but peddling the old “Linux doesn’t get viruses” line does not make for credible journalism. (don’t use the J word!–Ed) Linux servers are compromised all the time. It’s a little too easy for your run-of-the-mill script kiddie to find their favourite exploit in Metasploit, find some vulnerable servers via shodan.io and create havoc. Attacking desktop Linux is a little more delicate, but that’s not to say it doesn’t happen. Rogue websites may serve drive-by downloads, bona fide websites may get hacked…

The WannaCry damage could have been much worse had it not been for the actions of one Marcus Hutchins (aka MalwareTech), a security researcher who noticed WannaCry was trying to contact a server at an unregistered domain. Feeling inquisitive, he duly registered the domain and set up a sinkhole, a server designed to capture information, which had the effect of neutering the malware. Once infected machines were able to contact this domain they stopped trying to infect other machines: in short, Hutchins had found a killswitch. Further variants of WannaCry appeared in the aftermath, and mercifully killswitch domains were found for these too. Hutchins became something of a hero overnight, which makes the next part of the story quite upsetting. In August 2017 he was in Las Vegas attending the…

Back in the days when virtually all open source software was licensed under the GPL, building a business around it was quite a challenge. MySQL was one of the first projects that attempted to create a true-blue ‘enterprise open source’ product by creating new licensing terms and adding exceptions to work around restrictive licensing. The proliferation of permissive licenses opened the flood gates, both for the use of open source software in the enterprise and for setting up professional support business around these products. Despite the fact that these days virtually all major open source software has a corporate backer that works with the community, mixing the two without burning your fingers is quite a balancing act. We caught up with Robin Schumacher, SVP of Products at DataStax, at the…

Artificial Intelligence (AI) and machine learning (ML) have entered the mainstream in the last couple of years. These technologies are now making their way into the next generation of databases as well. Administering large databases that operate complex workloads isn’t a simple feat, considering the amount of configuration settings that need to be managed. An increasing number of database vendors are thus infusing AI and ML in their databases in order to relegate some regular monitoring and optimisation tasks to an autopilot that can then assist admins tune the databases for maximum performance. “For decades, the primary time-sink for administrators has been routine maintenance and performance monitoring/tuning tasks that ensure each database system is optimised for its supported applications,” says Robin Schmacher. “The promise of well-designed AI and ML functionality…

My friends, You may feel as though you are isolated, have no one to turn to, or feel like you do not matter. But these feelings are not a true reflection of you and your worth. Our thoughts are capable of great things, but they can also cause great harm to ourselves. We are all part of a community, a place where we surround ourselves with those who share a similar interest or ideal. Whether it is a small computer, operating system or a way of working, we all share a passion for something and that may be the genesis for a community to form. A community is made of friendship and respect, both of which are earnt over time. The friendships we make online in forums and social media…

Our project is best used on boot, so here are the extra steps to make that happen. First we need to make our code executable, and for that we need to open a terminal and type Now to make the code available to everyone as a command, we need to copy it to /usr/bin, so in the terminal type Now give the command a try. In the terminal type the following and watch the OLED screen. So now we have the command, let’s use it on boot. In the terminal we shall use crontab and edit cron to start the command on boot, and run the command every minute that the Pi is on. In crontab, go to the bottom and add this line. Now save by pressing Ctrl+X and…

Now that you have mocked up the circuits on a small breadboard, what next? Ideally we would have all the parts and processes to construct our own MOSFET circuits, installed on working printed circuit boards that we designed and etched ourselves. But that’s not going to happen for this writer! Why build when you can buy? There are a number of versions of MOSFET power-switched modules and bidirectional-level converter printed circuit boards available on the market today. A search for “MOSFET trigger” or “bidirectional level converter” will return plenty of results. You can find two good examples at http://bit.ly/lxf254llc and http://bit.ly/lxf254mos. We’re not specifically endorsing or a recommending these product or their distributors – these links are provided to demonstrate that ready-made products are available.…

Everyone needs a note-taking app – a way of quickly scribbling anything from a to-do list to a detailed breakdown of an upcoming project. When it comes to choosing which app to trust with your notes, you’re spoilt for choice. One place you won’t find a notes app is in your default Ubuntu installation, however – you’ll need to make a choice. In this tutorial we’re going to focus on two note-taking apps, Standard Notes and Joplin. They share some common features: they’re both open-source, naturally, both support syncing and work across multiple platforms, so you can access and update your notes from anywhere. But there are also some notable differences, which means you’ll probably find one is a better fit for your needs than the other. While Standard Notes…

In its free form, Standard Notes is a capable text-based notes editor. But if you’re willing to shell out for an Extended subscription, you’ll gain so much more. First, you unlock access to almost 30 extensions, including a range of different themes and editors that enable you to introduce word-processor-like formatting to your notes, with support for images, tables and other elements. There’s even an editor for creating simple spreadsheets. The feature list is undoubtedly impressive, and you can road-test all this for free by visiting https://standardnotes.org/demo, where you’ll get access to a web-based demo account that you can navigate and use as if logged into your own account. The biggest issue is the pricing: currently only a subscription-based model is available, with prices ranging from $9.99 a month to…

If you’re a fan of Android devices, you’re probably aware that Android Studio is the application recommended to develop apps. Using it is pretty involved, but check out Kent Elchuk’s intro in LXF233 if you want to give it a go. If you’ve already installed Android Studio and are currently using it to build apps for your device, the good news is that you already have adb-tools as well. You’ll just need to find them. Take the following steps to locate your adb binary: 1 Open Android Studio. 2 Click the SDK Manager button on the toolbar, or from the Tools > Android > SDK Manager option in the main menu. 3 At the top of the dialogue that appears, there’s a field titled Android SDK Location. Find the directory…

HashiCorp Terraform is a product that enables you to define infrastructure as code, which includes physical hardware, virtual machines and containers as well as email and DNS providers. Put simply, you can describe your infrastructure and then you can update it and make changes to it using plain-text files. The use of these files means that you can automate, share, review and version-control your Terraform infrastructure definitions, while making it easy to read and understand and easily available to all team members. Terraform will also build a graph of all your resources to help you get a higher-level view of them. The two main stages of a Terraform project are planning and deployment. You first design and describe your infrastructure and discuss it with other members of your team before…

Suckless Tools are based on Plan 9, a system developed by Bell Labs that implements most of the *Nix based systems in a more network-centred way. Werc is a web-based attempt at doing the same thing as Plan 9, with a heavier focus on web pages. It uses plan9 commands to install. Find the details at http:// werc.cat-v.org. For an interesting take on distributed operating systems like Plan 9, take a look at Inferno at www.vitanuova. com/index.html. It runs as a standalone application, or as an OS.…

EBOOK READER Foliate Version: 1.5.0 Web: https://github.com/johnfactotum/foliate According to J.K. Rowling, “If you don’t like to read, you haven’t found the right book”. But it’s important to add that your attitude to reading in electronic form is greatly impacted by the software we use for it. There is a whole slew of ebook readers for Linux that have existed for ages. Still, there is a room for another even better ebook reader, and we think we have found the one. Foliate is a sleek GTK3-based and JavaScript-powered desktop application that was limited to the ePub format, but the latest release adds Mobi and Amazon Kindle formats (MOBI, AZW and AZW3). While that means that you’ll need other software to handle PDF or DjVu files, Foliate is perhaps the most polished…

Assembly language is particularly useful for writing device drivers and for writing methods and functions that control and interrogate hardware (embedded systems). It’s also very useful to help learn how computers and compilers work. To install, type gcc –-version at the command line to make sure that you have glibc installed. Install it if it’s not installed. Type gdb –-version at the command line to make sure that you have GDB installed. Install it if it’s not installed. Install YASM Install ddd and you’re done. The best way to follow along with this guide is to get the files for this tutorial from the DVD or from https:// github.com/jschwartzman/ asm-tutorial. When the gnu compiler gcc is used to compile a C program, the output of gcc is actually assembly language.…

If you receive a ‘Script not found’ error, this probably means that you don’t have the mod scripts installed in your Minecraft directory. Check that you’ve replaced .minecraft with the one from McPiFoMo; this should include mcpipy, which will be full of Python files (identified by the extension .py). If you receive a ‘Cannot run program “python”’ error, your game cannot locate Python. Ensure you’ve got the latest version of Python installed, and that it’s installed in Path. In a Bash shell, type export PATH=”$PATH:/usr/local/bin/python” to check it. Should you come into any problems with memory leakage or infinite loops, you can stop a script that’s running by just typing /python again in Minecraft, as only one script can be run from the game at any given time. If you…

USING THE LXFDVD Using Linux for the first time can be very confusing. It’ll be unlike anything that you’ve likely operated before, especially if you’re used to Microsoft Windows or Apple macOS. Generally our DVDs are designed to be run directly, which is to say that when you first power on your PC (or Mac) it should ‘boot’ from the DVD – so before Windows or macOS even starts to load – with Linux running directly from the DVD. This trick is known as a Live Disc. It enables you to try out the various versions of Linux without having to install or change anything on your PC. Just remove the DVD, restart your PC and it’ll be exactly as you left it. While many systems will boot from a…

Is Ubuntu about to stop being my daily desktop driver? Probably not today, probably not tomorrow – but next year, the year after that, perhaps? Since 2004 Ubuntu has been making Linux users’ lives easier offering access to all the software their heart’s desire, but what happens when access to that software stops? My bet is people go elsewhere. I don’t play games much, but I do game and I want access to my 15-year old Steam (for better or for worse) and GoG accounts. Canonical has clearly said 32-bit library support is basically on life support, so it feels like the time to up sticks and find a new home is approaching. That’s not to say Ubuntu is bad – it is without doubt superb for what it’s designed…

Virtual reality appears to be sticking around, whether you like it or not, and now two of the most popular Linux desktop environments, Gnome and KDE, support it. As Lubosz Sarnecki writes in a blog post announcing VR support (http://bit.ly/LXF254LinuxVR), the early days of VR on Linux were rough, to say the least. Virtual reality headsets were treated as a second monitor, which simply extended the desktop onto it. Now a new open source project has been created, called xrdesktop (http://bit.ly/ LXF254xrdesktop), with a goal to render traditional desktop environments like GNOME and KDE in virtual reality 3D space – while allowing users to interact with them via VR controllers. For example, you can hold the trigger button of the VR controllers that come with the HTC Vive headset to…

Linus Torvalds announced the first few release candidates for what will become Linux 5.3 in a few more weeks. In his announcement, he noted that 5.3-rc1 was a “pretty big release, judging by the commit count. Not the biggest ever that honour still goes to 4.9-rc1, which was exceptionally big. He also noted that this cycle had “started out pretty painfully” due to a few bugs in the first few days but had “mostly smoothed out towards the end of the merge window”. Finally, he reminded us that there were about 1,600 individual developers in Linux 5.3, many more than the maintainers shown in the changelog listings. “There had been a few patches merged through the graphics tree that really annoyed Linus.” During the 5.3 merge window there had been…

Build Brighton Thursday evening is open night. http://buildbrighton.com Cornwall Tech Jam Second Saturday of the month, alternating between Bodmin and Camborne www.cornwalltechjam.uk Thingqbator An IoT-focused makerspace, meeting weekly at The Shed MMU. mcr.thingqbator.org Leeds Hackspace Open night every Tuesday 7pm-late. Open day second Saturday of the month, 11am-4pm. http://leedshackspace.org.uk Huddersfield Raspberry Jam Meet every month at Huddersfield Library, typically the fourth Saturday of each month. Huddersfieldraspberryjam.co.uk rLab Reading Hackspace Unit C1, Weldale St, Reading, Open Sessions Wednesday from 7pm. http://rlab.org.uk Horsham Raspberry Jam Park Side, Chart Way, Horsham. www.facebook.com/hackhorsham Maidstone Hackspace Holds open evenings every Wednesday from 5:30pm to 8:00pm. https://maidstone-hackspace.org.uk Glasgow Makers and Hardware Hackers Mitchell Library, Glasgow. www.facebook.com/groups/115303729096198…

Graphical file managers let you view the contents of a directory or one of its subdirectories, as do the ls and dir commands in the shell. Most graphical managers also let you view directories in a tree format where you can see both subdirectories and their contents in a single view – but what if you want to do the same in a terminal or SSH session? There is a command-line tool that does just this, and it is called tree – no cryptic two-letter name here. Run with no arguments, tree prints a listing of the files and directories in the current directory and those below it. As with ls, you can pass the name of a directory to list and there are several options that alter the output.…

Send your thoughts to the Linux Format dungeon server at linuxformat@futurenet.com, be picked as Letter Of The Month and win* a 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.…

Zen 2 is more than just a die-shrink. At a high level, AMD claims its IPC (Instructions Per Clock) are 15 per cent higher than Zen+. So for the same number of cores and the same clock speed, Zen 2 should be 15 per cent faster. But how did AMD get that improvement? It’s all in the architectural details. One big update is the doubling of the L3 cache size. On the singlechiplet Ryzen 5/7 parts, there’s a 32MB victim cache – meaning that data in the L2 cache doesn’t get replicated into the L3 cache. An exclusive cache, if you prefer. The dual-chiplet Ryzen 9 CPUs, meanwhile, come with a combined 64MB L3 cache. So what do those massive cache sizes do for memory latency? AMD says on average…

Many computer users probably consider the text editor as a left-over of a bygone age that has been superseded by the word processor. However, as more technically minded users will know, a word processor isn’t just a bigger and better text editor; the latter is quite different and it continues to have a role today. Most importantly, it generates a file containing plain ASCII text. Now of course a word processor can export as plain text, but even so, unless you pay careful attention it will often attempt to format your text automatically and correct spelling mistakes – which might not be mistakes at all. Here we’re taking a look at five text editors that cover a broad spectrum of uses. Perhaps the most common use is for programmers to…

Nano offers nothing that could be considered over and above the basics of text editing. FocusWriter provides just those features aimed at preventing distraction – even by yourself – as discussed in the Overview. Brackets’ advanced features mostly concern its main application of web development. Included here are live preview of HTML/CSS, and a quick-edit feature that enables you to open up a linked CSS or JavaScript file for editing while editing HTML. Atom provides a lot more than just basic text editing. Perhaps its most commonly cited advanced feature is integration with git/ GitHub, to provide facilities such as version control and collaborative features – including access control, bug tracking, feature requests and project management. Although it has to be added separately, another impressive feature called Teletype facilitates teamwork…

A couple of times during our conversation, Robin alluded to the fact that DataStax has now set its eyes on helping users eradicate some of the day-to-day operational complexity from their workflow. The DataStax Apache Cassandra as a Service is one of the initiatives announced during the conference that’ll help it meet this lofty objective. The database-as-a-service (DBaaS) product aims to simplify app deployment and development provisioning by reducing the process to just a few clicks. Robin tells us that to make the cloud offering more enticing, DataStax has rolled it along with enterprise grade security and offers it on usage-based pricing terms. He adds that it’ll also get the self-healing features that ensure users don’t have to deal with certain administrative functions that are a headache to deal with…

NoSQL databases provide the performance, scalability and stability that’s required by the modern data-driven apps we interact with these days. But that is where the similarity between NoSQL systems end. In fact, it wouldn’t be wrong to say that the only thing most NoSQL databases have in common is that they do not follow the traditional relational data model. Broadly speaking, NoSQL databases typically fall into one of four categories: Key-value These function in heavy read environments. Key-value stores are the simplest form of NoSQL databases and won’t be of much help when there are complex relationships between data elements. That’s because all access to the database is done using a primary key. Redis and Memcached are frequently used solutions. Columnar These are optimised for reading and writing columns of…

We had a level of head-scratching when it came to popping a roof on our building – two, in fact. Problem one was a lack of available roof models. Luckily there are add-on packs (see https://sourceforge. net/p/sweethome3d/d-models/257) that do an excellent job of offering a range of usable roofs, rather than cobbling a coloured pyramid or triangle model on top, which is what we first went with. The other issue was how to add it to the plan itself. We went with adding an extra ‘floor’, but at the same elevation as the existing floor. So for a ground-floor extension, add an extra floor at the ground-floor elevation. You can position the roof on the existing ground-floor plan, then cut/paste it to the new floor created for the roof. The…

If you’re not able to see a connected device with the ‘adb devices’ command, or you get an error, try the following. The first will install the adb package containing the required plugdev rules. The second adds your user to the plugdev system group: ‘sudo apt install adb’ ‘sudo usermod -aG plugdev [your username]’ In the event you leave your cable at home, you can restart the ADB server with a TCP/IP port number (it defaults to USB mode), and connect to your device with: ‘adb tcpip 5555’ ‘adb connect [IP address of device]:[port]’…

HashiCorp Consul is a service mesh solution or, if you prefer, a multi-cloud service networking platform that enables you to connect and secure services in dynamic infrastructures across any runtime platform and cloud provider. The key features of Consul are a service directory, health checking, key/value storage, support for multiple data centres and service segmentation. Put simply, Consul acts as a service registry that keeps track of available services and returns information about these when asked. If one of the instances of a service dies, Consul will notice and not return the address of that instance. If that instance becomes healthy again, it will inform the Consul registry and it will return its address once more. The whole thing simplifies service-orientated architectures because you do not have to keep track…

When you start using dwm, you will need shortcuts to do anything. The reason is that starting an application can only be done with a terminal or dmenu – at least, this is the default behaviour. You may also use vim, Emacs or something similar. Once you start using keyboard shortcuts or key chords, you start looking for them everywhere: who needs a mouse to browse the web? Use vimify or similar to browse with vim keyboard shortcuts. With sxhkd, you can define your own shortcuts for the whole system. It runs as a daemon and has simple and powerful setting file. To bind your favourite application to a specific key, add it to the configuration file. The keyword to bind your keys are clear and the format of the…

A CPU has a limited number of registers. In order for Linux, C/C++ and assembly language programs to play together nicely, you need to know which registers you can change and which you must preserve. You need to know which registers will be changed by the functions you call and which will be preserved. You need to know which registers will be used to pass arguments into your functions and in what order. The same goes when you want to pass arguments to a function. Your assembly language programs will only work if you obey the same rules that the Linux kernel and C obey. The six argument-passing registers, in order, are RDI, RSI, RDX, RCX (substitute R10 for Linux syscalls), R8 and R9. So the first argument is always…

When you’re coding an item to appear near your player character you’ll usually want to add/minus a coordinate on the x/y axis, or it’ll appear inside you. Module commands setBlock and setBlocks are mutually exclusive. Remember if you’re placing in the singular or plural to use the correct API call, or your block(s) won’t spawn. If you see red text stating Minecraft or Python ‘Cannot find script’ be sure to check the name and location of your .py file – it should be saved in mcpipy.…

THE LXF LIBRARY 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…

“In recent years, several milestones have been achieved towards making Linux the best environment for VR and AR. The Linux graphics stack was made aware of head-mounted displays via DRM leasing, Khronos specified the OpenXR standard API, and Monado became the first OpenXR runtime for GNU/Linux. The ability to interact with the desktop from XR is one of these milestones. In contrast to existing VR-only window managers for Linux, the new open source project xrdesktop integrates into traditional desktop environments, allowing you to seamlessly interact with a Gnome or KDE desktop from VR. The libraries implement interaction with 3DUI elements, generate mouse and keyboard events from VR controllers, and can be integrated into any X11 and Wayland window manager. The OpenVR API is supported, making xrdesktop usable with headsets like…

Purism, the team behind the much-anticipated Librem 5 smartphone which runs a Linux-based operating system focusing on security and privacy, has released the final specifications for the handset (http:// bit.ly/LXF254Librem5specs), and they point to a pretty capable high-end smartphone. The specs include a 5.7-inch IPS screen with 720 x 1440 resolution, an i.MX8M quad-core processor, 3GB RAM, 32GB storage, Bluetooth 4, 8-megapixel front camera and 13-megapixel rear camera. Like most modern (non-Apple) smartphones, it uses a USB-C port to charge and transfer data, and it also has a few features that most smartphones these days sadly lack, including a user-replaceable 3,500mAh battery.…

“Greetings reader. Thank you for joining me over here by the forgotten column. Here’s a fact: I’ve made nearly a dozen LXFDVDs now, and they mostly seem to have worked. Or at least no one has complained. Amazing. There’s all kinds of subtle awkwardness involved in making distros boot from an ISO file, but fortunately, thanks to disc editors past we have a record of each flavour of Linux’s peculiarities. Big distros like Fedora and Ubuntu support ISO booting out of the box (each in their own way), but for some reason their derivatives have a terrible habit of removing this support. This issue was particularly tricky because Mageia is a little different. It uses the same tool as Fedora (Dracut) to make its initrd, but seems to have gone…

Palmer Dabbelt (the RISC-V maintainer) posted a patch implementing a new Linux system call, named fchmodat4(). The existing manual page for fchmodat says that it takes a ‘flags’ argument, but the existing system call does not, meaning that certain scenarios aren’t covered in the existing code. These include cases where a user wants to override the handling of symbolic links. Yang Weijiang posted “Enable Sub-page Write Protection Support”, patches that enable Virtual Machine Monitors (VMMs) such as KVM or Xen to provide ‘sub-page’ level privileges for regions of memory. Typically, Linux manages memory in pages that represent the smallest unit of memory that can be handled by the underlying hardware. In sub-page support, Intel enables an ability to manage protections in a much more fine-grained manner. This is especially useful…

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 highly nested search algorithm), 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…

Largely because our group is so wide-ranging, we started out by providing an overview of all the packages on offer – see Overview on page 30 for this. You might like to read that first before getting bogged down in the details. In terms of specifics, there were several topics we needed to consider but, in some cases, they didn’t apply to all the products. So we certainly needed to consider which programming languages are supported (all but one of these programs have such support). Areas that apply universally are file format compatibility, support of multiple views, ease of use and expandability, all of which we consider. To make sure we didn’t miss anything, in the Advanced Features sections we’ll pass comment on any stuff that we didn’t cover elsewhere.…

If you’re an Ubuntu user, you’ll find that you already have the GUI text editor Gedit and the command line editor Vim (accessed by the vi command rather than vim ) pre-installed on your system, so these would be easy ones to try out. For other distributions, you might discover Mousepad, Kate, Pluma, Xed or LeafPad already installed for you to test-drive. Others which are highly respected include Sublime Text, which is free to trial for an unlimited period, but for which you are trusted to pay $70 for continued use; and Visual Code Studio, which is unusual in being an open-source Microsoft project. Add to these jEdit, Cream, SciTE, Geany, Bluefish and Kwrite, and you’d have a major job on your hands in deciding which to use. What’s more,…

A number of high-profile organisations have paid ransom fees, and we are likely to see a lot more of this unless our collective security game is upped. Large organisations with lax security practices can (but shouldn’t) be crippled by a careless employee falling for an email scam. This may be an untargeted attack, where the ransomware keymasters’ expected targets are unsuspecting home users, in which case the asking price is pretty modest. Or it could be some kind of spear phishing campaign, where execs or sysadmins are targeted so their privileges or well-endowed bank accounts can be ransacked. And if you’re going to cripple a large organisation you’ll probably be after more than pocket change. In June of this year, Riviera Beach City Council in Florida agreed to pay a…

Google’s Authenticator app for Android is a software 2FA solution, albeit a proprietary one, that uses the Time-based One-time Password protocol (TOTP) to generate six- to eight-digit one time codes for use as a second factor. It’s widely supported, not just on Google sites, so if you have an Android phone this is a free way to boost your security and reduce the chance of unfortunate takeovers. The magic of this is that, once a token is generated and shared between the site and the app, the same code is generated independently based on the current time. The algorithm can tolerate clock skews and network latency, so the app and the site don’t need to both keep exactly the same time. Authenticator codes can theoretically be spied on, though an…

This is the information era, where almost everything is data. The scale at which this data is being collected and used is growing at an exponential rate. The speed at which organisations are ingesting, storing and processing data is hard to fathom; it’s very common these days for even small-scale companies to process terabytes and even petabytes of data. In order for this data to be crunched into meaningful information, it first needs to be housed in a database. Databases have become a part of your daily routine in more ways than you can imagine. These days you don’t even have to be on a computer or use your smartphone to interact with a database. For instance, when you purchase items at the local supermarket, chances are there’s an inventory…

One maker duo is prototyping a smart buoy for monitoring sea waves, temperature and more. While the project doesn’t seem to have official bodies backing at the moment, it’s certainly interesting in itself to see how the Raspberry Pi and, more widely, maker skills can help create devices that make a difference in the real world. The Smart Buoy is built from a 3D-printed hollow sphere and is powered from four integrated solar panels, It uses a Pi Zero and Arduino board, and is outfitted with a host of sensors plus a radio antenna. The aim of the prototype buoy was to measure wave dynamics along with sea and air temperature, communicating those details via the radio. The Grenadian government gave the team approval to set the buoy free along…

This issue’s project is a tiny OLED screen that will provide useful data about a Raspberry Pi at a glance. We will also run our project on boot to monitor the system as we work. The OLED screen connects to the Raspberry Pi GPIO using an I2C interface. This is a special interface that only needs four pins on the Pi in order to send data. To connect your Pi please refer to the diagram on page 53. With the physical connection made we now need to enable I2C on our Pi – do this in the Raspberry Pi Configuration tool. We will also need to install two Python libraries for this project. The first library is for our OLED screen and the second enables our code to work with…

An inductive load (as opposed to a resistive load) describes any device that contains a motor, such as a refrigerator, an air conditioner or a device containing a coil, like a relay. You may have noticed that when you first turn on a device with a motor in it, the house lights sometimes dim very briefly. The motor has coils of wire turning inside a magnetic field that produces an electromagnetic field (EMF). This EMF, referred to as back EMF, is acting against the voltage that was applied to get the motor to spin. When the voltage is removed from the coil by stopping the motor, a back EMF is also produced. Back EMF doesn’t want the current to increase (at motor start) and back EMF doesn’t want the current…

As TMSU only creates a symbolic link to all the tagged files and directories, the database can easily get out of sync with the actual files on the disk if you were to move the files or rename them. This is because TMSU doesn’t watch the filesystem for changes. You can run the tmsu status command to determine whether the database is out of sync or not. When run without any additional command options, the status command will check each file in the database with the corresponding file on the disk. The filenames it produces as output are preceded with either T, M, ! or U symbols, identifying the respective files as either Tagged, Modified, Missing or Untagged. Renamed files, identified with the ! symbol, which still reside in the…

When you start adding tags to your notes in Standard Notes, separate individual tags with the # symbol – for example, type #dvd #media. Tags appear in the left pane; click one to show options to rename (this updates all notes with that tag) or delete it. Add additional capabilities to Joplin’s markdown editor by toggling various settings on or off via ‘Tools > General Options’. Scroll down to the Plugins section where options such as soft breaks, support for subscript and superscript syntax and even emojis can be enabled. Joplin makes it possible to nest notebooks inside other notebooks as sub-notebooks. Just drag an existing notebook on top of another notebook to move it inside that notebook. Drag a sub-notebook on to the Notebooks header to move it back…

Android manufacturers have a great deal of leeway on how much they customise the Android OS they will put on their devices. It is an open source project after all, but even within the bounds of ‘official’ Google Android, they can change a lot. This is because, unlike a traditional OS, each one corresponds to a single device model – for reasons mentioned in the article. As a result, you may see many folders above and beyond those listed here in your device, or some you may not even see at all. In Note 5, for example, I also see directories including: config, cpefs, efs, factory, knox_data, oem, persdata, preload and storage. The purpose of some of these is evident; for example, /storage is where links like /sdcard and /mnt/sdcard…

There’s more general information about HashiCorp Vault at www. hashicorp.com/products/vault. Additionally, you can learn about the Vault API at www. vaultproject.io/api or visit the official Vault documentation site at www. vaultproject.io/docs. Vault is open source software written in Go. This means that you can look into its code, improve it or even find a security issue with Vault and report it. Who knows, you might end up working for HashiCorp! The HashiCorp Configuration Language (HCL) tries to be both machine- and human-readable, which means that it should be easy to understand and modify by humans and easy to parse by computer programs. This is the main reason that HashiCorp products use their own text format for configuration files. Learn more about HCL at https:// github.com/hashicorp/hcl.…

The dwm window manager is minimal and efficient. However, at the present time it runs on X exclusively. Efforts to port it to Wayland is underway. Until that is stable, you can choose Sway. This is a tiling window manager that has the slim build of dwm and its tiling magic too. Sway is a fork of the i3 window manager. The big difference is that it has support for, and relies on, the Lua programming language for configuration. For simple configuration, you do not need to learn programming. It is simple to change what is already in the standard configuration to suit your needs. If you do want to have advanced enhancements, you should use Lua. The use of Lua might offend purists, and it is a bit heavier…

Python code is sequential, so things will happen pretty instantaneously and consecutively, in the order that you’ve programmed them to take place. Whether you’re placing blocks in the environment or moving your player character around the world, you may want to space out your commands and do things at your own pace rather than everything happening instantaneously. To do this we can use Python’s ‘time’ module. Using the time.sleep command, we can create an artificial gap in our code to temporarily pause the program. time.sleep(10) would pause the program for 10 seconds before initiating the next line of code. This could be useful if you wanted a certain block to appear every x amount of seconds, or if you fancy moving a player around at specific intervals. In order to…