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Raspberry Pi 3 is a cheap single board computer (SBC) or simply microcomputer. It can be used to teach programming to kids, do electronics project, run a small home server and many more. The possibilities are limitless. Raspberry Pi 3 also consumes very low power. You can even keep a Raspberry Pi 3 running for a long time with an ordinary Mobile Power Bank that you use every day to charge your Android phone. Isn’t that amazing? You can say good-bye to your expensive UPS and keep your Raspberry Pi microcomputer running as long as you want in case of power failure with very low cost in your home. Raspberry Pi 3 Model B and Raspberry Pi 3 Model B+ is the last two revisions of Raspberry Pi 3 single board computer. Fig: Raspberry Pi 3 Model B (picture from https://www.raspberrypi.org/products/raspberry-pi-3-model-b/) In this article, I will talk about Raspberry Pi 3 Model B and Raspberry Pi 3 Model B+ and its power requirements. So let’s get started. Hardware Specification of Raspberry Pi 3 Model B: Raspberry Pi 3 Model B was released in February 2016. It has 64 Bit Quad Core 1.2 GHz Broadcom BCM2837 CPU. The CPU architecture is ARMv8. 1 GB of RAM Soldered on Board. On Board Wireless LAN. On Board Bluetooth Low Energy 4.1 (or BLE 4.1). 10/100-Base-T Ethernet Port (RJ-45). 4 USB 2.0 Ports. 40 GPIO Pins for connecting and controlling other electronic devices and different Raspberry Pi modules, such as Raspberry Pi Camera module. 4 Pole Stereo Audio and Video output via 3.5mm connector. HDMI port for Audio and Video output. micro USB port as power supply. An On Board micro SD Card Slot. Difference Between Raspberry Pi 3 Model B and Raspberry Pi 3 Model B+: In March 14, 2018, the Pi Day 2018, Raspberry Pi 3 Model B+ was release with slight hardware improvements. Raspberry Pi 3 Model B+ has a 1.4 GHz Quad Core Cortex-A53 (ARMv8 architecture) CPU, which is slightly faster than the CPU of the Raspberry Pi 3 Model B. Raspberry Pi 3 Model B+ has Bluetooth Low Energy 4.2. Raspberry Pi 3 Model B has Bluetooth Low Energy 4.1. Raspberry Pi 3 Model B+ can boot from the USB 2.0 storage devices such as USB thumb drives connected to the USB 2.0 ports by default. Boot from USB 2.0 devices connected to the USB 2.0 ports of Raspberry Pi 3 Model B is disabled by default. You will have to manually enable it. But both Raspberry Pi 3 Model B and Raspberry Pi 3 Model B+ can boot from micro SD card connected to the micro SD card slot. Raspberry Pi 3 Model B+ has support for 2.4 GHz and 5 GHz WiFi channels but Raspberry Pi 3 Model B does not. Raspberry Pi 3 Model B+ has support for PoE over the Ethernet port (RJ-45), which Raspberry Pi 3 Model B does not. Raspberry Pi 3 Model B and Raspberry Pi 3 Model B+ has 10/100 Mbps Ethernet port (RJ-45) on board. But if you want to connect a Gigabit Ethernet to your Raspberry Pi, you can on Raspberry Pi 3 Model B+ using a USB 2.0 Ethernet LAN card. But the speed will be limited to 300Mbps. On Raspberry Pi 3 Model B, you can’t do such thing. That’s basically the main difference between Raspberry Pi 3 Model B and Raspberry Pi 3 Model B+. I have Raspberry Pi 3 Model B, so that’s what I will be using in the upcoming articles. But it should be applicable to Raspberry Pi 3 Model B+ as well without any changes. Power Requirements of Raspberry Pi 3 Model B and Raspberry Pi 3 Model B+: You need a 5V, 2.5 Amp micro USB power adapter for powering your Raspberry Pi 3 Model B and Raspberry Pi 3 Model B+. You can use many of the good Android phone charger to power on your Raspberry Pi 3 Model B and Raspberry Pi 3 Model B+ device. You can also use a regular power bank that you use on your phone to power on your Raspberry Pi 3 Model B and Raspberry Pi 3 Model B+. Any Android phone charger and power bank should work. But I recommend you don’t use bad or cheap chargers. The cables in those chargers are not good. So, voltage drops in the cable, leaving less than 5.0 V for your Raspberry Pi 3 Model B and Raspberry Pi 3 Model B+ microcomputer. In that case, when you power on your Raspberry Pi 3 Model B and Raspberry Pi 3 Model B+, it should boot, but you will see a small lighting symbol on the screen. The lighting symbol means, your Raspberry Pi 3 Model B and Raspberry Pi 3 Model B+ is running on low power mode. If you connect power hungry USB devices to your raspberry pi, it may reset on its own as it does not have enough power to run properly. Power Consumption of Raspberry Pi 3 Model B and Raspberry Pi 3 Model B+: Raspberry Pi 3 Model B consumes less power than Raspberry Pi 3 Model B+. Raspberry Pi 3 Model B consumes about 260 mA of current at 5.0 V (which is about 1.3-1.4 Watt) when no USB devices are connected to it and it’s in idle state. Raspberry Pi 3 Model B+ consumes about 400 mA of current at 5.0 V (which is about 1.9-2.1 Watt) when no USB devices are connected to it and it’s in idle state. If you add more accessories to your Raspberry Pi 3 Model B and Raspberry Pi 3 B+ or if it’s not idle (working), then the power consumption will increase. Saving Power on Raspberry Pi: If you want to save power, you should of course connect less accessories to your Raspberry Pi and disable the features that you don’t need. So, that’s it. Thanks for reading this article. ...

Top GIF Recorders For Linux Whether you pronounce it as ‘gif’ or ‘jif’, it’s still a no-brainer that the Graphics Interchange Format is the most widely used image format there is today, gaining in popularity exponentially. This surging bitmap image format is used for a number of purposes, most of which include producing eye-catching animations to improve digital marketing. However, due to its convenience of storing multiple images in the same file while retaining file compression, it is also now considered a popular alternative to screen recording. While there’s a lot of support for GIFs on Windows and other operating systems like Android, they can also readily be produced on Linux with a lot of flexibility and in the best quality. Let’s look at some of the most popular GIF recorder tools used to produce GIFs on Linux. 1. Peek If you’re looking for a GIF recorder tool with minimal, straight-forward features required only for basic GIF-making support, then Peek is perfect for you. Its basic features include the ability to edit frame rate and delay timer. It doesn’t have advanced features but is complete if you want to make a quick GIF with not many control requirements. Hence, its user interface (yes, Peek is a GUI-based recorder) is also very simple to understand and navigate. For beginners, Peek should be the go-to GIF recorder. You can easily take screencasts of a Linux desktop and compile them into a short, compressed animation using Peek’s GIF recorder. You’ll only need to place the recorder window on top of the screen area you want to record and start recording! It’s also very simple to install Peek via the command line interface of the Linux terminal. For Ubuntu users, the commands that need to be executed for the installation are as follows: sudo add-apt-repository ppa:peek-developers/stable sudo apt update sudo apt install peek 2. Gifine If the basic editing features of Peek don’t fulfill your GIF recording needs, then Gifine is a good alternative. Gifine is a straightforward piece of software that may not offer the sleekest interface but certainly gets the job done. It offers built-in support for editing and trimming your gifs which can save a lot of time when it comes to making something special. Its installation is also not the simplest and can feel a bit cumbersome too. The problem is that it’s not a one-liner install command but an amalgamation of different commands that contain certain dependencies as well. It requires about 6 commands to be run successfully in order to be used. Although it is troublesome in the installation process, the benefits it brings certainly outweigh the initial barricades. 3. Byzanz The interesting thing about Ubuntu is that a large number of programs are given a command-line version and Byzanz is one of them. It is a gif recorder that runs on the command-line interface (CLI). This mode of usage allows it to be very small in size and frees up a ton of processing power that can be put to other use. The only drawback of Byzanz is that it does not support a normal Graphical User Interface (GLI) and is therefore not aimed at novice Linux users. The documentation that comes with Byzanz is good enough for even beginner users to start with and is a good recommendation for anyone who has a need for a gif recorder. It also gives good practice for getting used to the Linux environment and will make future tasks that run on the terminal much less daunting. 4. SilentCast SilentCast is a feature-rich gif recorder that has a fairly large userbase and is therefore constantly showered with upgrades and bug-fixes. It may not be the best-looking gif recorder but it certainly gets the job done and there is a good chance that you will not need to use other software to get the right product. SilentCast is certainly one of the most lightweight recorders out there but that edge comes with a little drawback as well. A series of terminal commands are needed to make it go live. If instructions are clearly followed then there won’t be any problem with the installation and you should have it up and running in no time! 5. Kgif Kgif is a small project on GitHub that makes creating gifs a breeze. The project only has 2 contributors so you should not expect a large number of features to be present here. It does what it is supposed to, nothing more and nothing less. Kgif makes use of the terminal to work and might not be the go-to choice of GUI enthusiasts. If you are low on resources and just want something that can give you a gif, Kgif will be all you need. There is a neat little feature here that allows you to set a delay for how long before the script should start capturing. It’s activated in a single command: ./kgif.sh –delay=x X will be replaced by the number of seconds you want the delay to be. 6. Gifcurry Linux is famous for having loads of free and open-source software that would otherwise be behind a paywall on other operating systems. Gifcurry is one such freeware on Linux and is a splendid experience along with as well. All basic gif editing functions are available here and there are also some options that can be used for video editing as well. These surplus features make sure that you won’t have to download two to three different software to complete your task. Not only does this save you time but also saves space. You just have to make sure that your system has the right dependencies installed before you can make use of Gifcurry. The dependencies are in no particular order: GTK+, FFmpeg, and ImageMagick. With everything in place, Gicurry should install in a breeze when you enter the following command on the Linux command: sudo snap install gifcurry Now that you know of a few of the best GIF recorders for Linux, you can evaluate their features against the function you need to perform and pick the best GIF recorder for you! ...

RHEL 8 đã được công bố vào dịp tháng 05.2019, thường lệ thì CentOS8 tương ứngcũng sẽ được lên kệ sau đó một tới hai tuần. Nhưng lần này thì không, mãi tới ngày hôm nay – 25.09.2019 thì CentOS8 mới được công bố. Lần ra mắt này thì CentOS được tung ra 2 phiên bản gồm: CentOS 8 như thường lệ và bản CentOS 8 Stream (tham khảo thêm về các lý do của CentOS8 Stream ở cuối bài). CentOS 8 stream là một bạn trung gian giữa CentOS 8 nhất và RHEL 8, mục tiêu là CentOS 8 Stream là bản mà cộng đồng lập trình viên đóng gói những ứng dụng mới nhất (tạm hiểu là thử nghiệm, thí điểm cho người dùng công khai) để thử nghiệm trước khi đưa vào bản RHEL 8. Trong bài viết này, Onet sẽ hướng dẫn các bạn trải nghiệm các bước cài trước khi thử nghiệm, hãy lưu ý bước chọn không có GUI (giao diện đồ họa) khi cài CentOS 8 bởi vì CentOS lần này cung cấp file iso dạng full (~7GB) chứ không có bản minimal. Lưu ý: Dùng bản không có GUI (giao diện đồ họa) cho máy chủ để máy chủ được nhẹ nhàng hơn, thường các sysad chuyên sẽ ý dùng GUI. Sau đây là các bước cài đặt CentOS8. Tải file ISO của CentOS 8 Bước 1: Tải ISO về để ghi ra đĩa hoặc dùng để mount vào khi cài trên KVM hoặc Vmware Workstation hoặc ESXi. Link tải ở dưới http://mirrors.nhanhoa.com/centos/8.0.1905/isos/x86_64/CentOS-8-x86_64-1905-dvd1.iso Cài CentOS 8 Tạo máy ảo trên các môi trường hoặc đưa đĩa vào trong ổ đĩa của máy cần cài (bước này tùy bạn làm ở môi trường nào nhé) Khởi động máy và chọn boot vào CentOS. Lựa chọn dòng Install CentOS Linux 8.0.1905 Chọn ngôn ngữ cho hệ điều hành, ở đây chọn English. Sau đó chọn Continute Chọn ổ cứng để cài OS, ở đây lựa chọn mục Installation Destination. Sau đó sẽ có giao diện mới. Chọn Done. Sau khi chọn Done, ta sẽ quay về giao diện tiếp và chọn mục Software Selection để lựa chọn chế độ không dùng GUI. Chọn chế độ Minimal Install để không sử dụng GUI cho hệ điều hành sau này. Sau đó chọn Done. Sau khi chọn Done, ta quay về màn hình lúc trước và chọn Time & Date. Nên chọn timezone chuẩn với giờ Việt Nam, quan sát ở bước tiếp. Di chuột vào khu vực Việt Nam ở bản đò, thanh region và city sẽ tự chọn đúng chuẩn. Sau đó chọn Done. Sau khi chọn Done, màn hình sẽ quay về danh sách các thiết lập. Tiếp tục chọn Network && Host Name để cấu hình IP và hostname. Sau khi chọn Network & Host name ta sẽ có giao diện chọn hostname và IP bên dưới. Ta click vào nút OFF để máy có kết nối về network. Sau đó nhập hostame tùy thích và chọn Apply Tiếp tục chọn mục Configure để cấu hình card mạng ở chế độ start cùng OS. Chọn tab Genaral và tích vào nút Automaticaly Connect to this network when it is avaible Sau đó chọn Save và chuyển sang màn hình dưới. Tiếp tục chọn Done để quay về màn hình menu chính lúc setup. Sau khi về menu chính, ta chọn Begin Instalation để thực hiện cài đặt. Sau đó nhập mật khẩu cho tài khoản root và chờ các bước cài đặt diễn ra. Lưu ý ghi nhớ mật khẩu này để dùng cho bước tới. Sau khi cài đặt hoàn tất, tầm khoảng 10-15 phút, ta sẽ có màn hình dưới. Chọn nút Reboot để máy khởi động lại và bắt đầu đăng nhập vào OS với tài khoản root và mật khẩu nhập trươc đó. Đăng nhập vào máy sau khi cài Sau khi cài xong, máy sẽ khởi động lại và xuất hiện giao diện để ta nhập tài khoản & mật khẩu. Nhập tài khoản root và mật khẩu. Sau khi nhập thành công, kiểm tra IP và kernel của máy CentOS8 bằng các lệnh ip a để biết IP và uname -rms để biết phiên bản kerenl Tới đây, ta đã kết thúc việc cài CentOS8, hãy sử dụng các phần mềm SSH khác để truy cập vào máy CentOS8 để kiểm tra thêm. Đăng nhập thử và kiểm tra việc kết nối internet. Kết luận Việc cài CentOS8 không có gì khác biệt quá so với CentOS7, chỉ lưu ý rằng ở bài viết này sử dụng file ISO DVD với dụng lượng khoảng 6GB, có nghĩa là file ISO gồm các gói phần mềm đầy đủ đi kèm với CentOS8. Và khi sử dụng file ISO này cần lưu ý bước lựa chọn không sử dụng GUI (tức là chọn bản CentOS Minimal). Onet cám ơn sự quan tâm và mong nhận được góp ý từ các bạn. Nếu bạn ngại đọc text thì xem thêm video này nhé Video hướng dẫn cài đặt CentOS8 Tham khảo Lý do có phiên bản CentOS8 Stream: https://www.redhat.com/en/blog/transforming-development-experience-within-centos ...