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The 4% rule: picking app background colors that survive cheap phone screens

Every design team eventually ships a beautiful off-white, off-blue, or off-anything background… and then opens the app on a $120 phone and watches it turn dirty gray . Same hex, same build. This post explains why, and gives you a small formula to convert any tint you've chosen into one that survives budget panels. Why subtle tints die on cheap screens Four panel-level failure modes, all common in the budget tier: 1. Weak gamut coverage. Entry-level LCDs cover only a fraction of sRGB — independent panel measurements routinely land in the 55–70% range, with large per-color error. A low-chroma tint simply doesn't have the budget to survive that compression. 2. Cold white points. sRGB assumes a D65 white (6500K). Budget modules commonly ship visibly cooler — high-6000s to 9000K+ — because blue-ish whites look "brighter" in a store. That blue cast is spread across the entire grayscale, and its magnitude is comparable to a subtle warm tint. Net result: the panel can cancel your background color outright. 3. Stretched gamuts on budget AMOLED. The opposite failure: "vivid" default modes stretch sRGB content across the panel's wider native gamut. Your quiet tint renders at roughly double saturation and suddenly has an opinion. 4. Banding. Many cheap panels are 6-bit + FRC. Soft near-white gradients develop visible steps, which makes barely-different surface colors look like rendering bugs. The 4% rule You don't need a colorimeter to know if you're at risk. Use channel spread — the distance between your highest and lowest RGB channel — as a chroma proxy: spread = max(R, G, B) − min(R, G, B) If spread is under ~10 of 255 (≈4%) , your tint is inside a cheap panel's error bar. It may render as intended, as gray, or as tinted the other direction — you don't get a vote. (Quick check on any hex: two outer pairs of digits within ~0x0A of each other = you're in the danger zone.) Why 4%? Because that's the same order of magnitude as the grayscale tint produced by a few-hundred-kelvin

2026-08-03 原文 →
AI 资讯

Architecting Mainline-Friendly Products

Mainline-friendly products are designed so their board support lives in upstream Linux, U-Boot, and standard build systems instead of a vendor fork. The decision is architectural, not aspirational: it is made when you choose the SoC, design the add-on connectors, and write the device tree — not when the product is already shipping. This article gives the strategic case, the product design rules that follow from current kernel work on hot-pluggable add-on boards, a vendor checklist for tech leads, and the concrete steps to upstream your own board support. We have covered why silicon vendors are moving to upstream-first BSPs . This article covers the product team's side of that shift: what you should do about it. Building mainline-friendly products means making a set of design decisions — SoC selection, connector design, device tree structure, and an upstreaming plan — so that mainline Linux and U-Boot treat your board as a normally supported board rather than as a permanent private port. Each section below turns one of those decisions into rules you can apply on your next board. Why mainline-friendly products are a strategic decision The cost of a vendor-fork BSP is not paid at bring-up; it is paid for the life of the product. Every kernel upgrade becomes a forward-port of private patches. Every security fix arrives on the vendor's schedule, not the kernel's — and for devices in scope of regulations such as the EU Cyber Resilience Act, patch latency is now a compliance question, not just an engineering one. Hiring is harder, because engineers must learn your fork before they can touch it, and the knowledge they build does not transfer in either direction. Board support that lives in mainline inverts each of these. New kernels are more likely to boot your board without forward-porting private support patches, because your board is part of the kernel's own build-and-test surface; LTS security fixes are easier to consume because the code paths you depend on are already

2026-08-02 原文 →
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How to Learn Linux in 2026 (Hands-On, Free, No Experience Needed)

Here is the whole method: get access to a real Linux machine, type commands on it for 30 to 60 minutes every day, and follow a plan that builds from navigating the filesystem up to running your own web server. Do that and you will be comfortable in four weeks and genuinely fluent in about eight. No experience required, no money required. The rest of this article is the specific plan: what to type each week, where to get a free machine you can safely break, what the three scariest errors mean, and how to tell you are actually improving. Why most people fail at Linux The pattern is nearly universal. Someone decides to learn Linux, finds a nine-hour video course, watches it at 1.5x speed, takes beautiful notes, and three weeks later cannot list the contents of a directory without checking those notes. Watching someone else type is not practice. It feels like learning because the explanation makes sense while you hear it. But command line skill is muscle memory wrapped around a mental model, and both are built one way: typing, failing, reading the error, trying again. An hour of reading about ls teaches you less than typing ls twenty times in twenty directories. Videos are fine as a preview. They are just not the workout. So flip the ratio: for every minute reading or watching, spend five with your hands on a keyboard. This article included. Read a section, then go type it. Two smaller failure modes show up almost as often. Trying to memorize everything Linux has thousands of commands. Working engineers lean hard on a core of about 25 and look up the rest without shame. The plan below teaches that core and nothing else. Fear of breaking things On a practice machine, breaking things is the goal, not the risk. A system you broke and fixed teaches more than ten flawless tutorials. Every option in the practice section makes the worst case "start over," which costs a minute. The four-week plan First, get a machine from the free options below (one minute to one afternoon, dep

2026-08-01 原文 →
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How to Verify a SHA-256 Checksum on Windows, macOS, and Linux

How to Verify a SHA-256 Checksum on Windows, macOS, and Linux You download an ISO, installer, archive, or release binary. The publisher provides a long value such as: 9f86d081884c7d659a2feaa0c55ad015 a3bf4f1b2b0b822cd15d6c15b0f00a08 That value is a checksum, usually generated with SHA-256. Verifying it answers one practical question: Does the file you downloaded have exactly the same contents as the file the publisher hashed? A checksum mismatch can indicate a damaged download, an incomplete transfer, the wrong file version, or modified contents. Before verifying anything Get the expected checksum from a source you trust. Ideally, use the software publisher’s official website, release page, package repository, or signed checksum file. A matching checksum confirms that your file matches the data represented by the expected hash. It does not prove that the original publisher or website was trustworthy. If an attacker can replace both the download and the displayed checksum, they can make the two values match. For stronger authenticity verification, use a signed release when the publisher provides one. Verify SHA-256 on Windows Open PowerShell in the folder containing the downloaded file. Run: Get-FileHash ".\filename.iso" -Algorithm SHA256 Example: Get-FileHash ".\ubuntu.iso" -Algorithm SHA256 PowerShell returns something similar to: Algorithm : SHA256 Hash : 4A1F... Path : C:\Users\You\Downloads\ubuntu.iso Compare the value beside Hash with the checksum published by the download provider. Uppercase and lowercase letters do not matter in hexadecimal hashes. The characters themselves must otherwise match exactly. Compare automatically in PowerShell Instead of comparing two 64-character values manually, store the expected checksum and let PowerShell compare them: $expected = "PASTE_EXPECTED_SHA256_HERE" $actual = ( Get-FileHash ".\filename.iso" -Algorithm SHA256 ) . Hash if ( $actual -eq $expected ) { Write-Host "Checksum matches" } else { Write-Host "Checksum does not

2026-08-01 原文 →
开源项目

Anleitung: Alienware m17x (2008) als Linux DJ-Workstation

moin, ich möchte euch mein aktuelles Projekt vorstellen: Die Wiederbelebung eines Alienware m17x (Baujahr 2008) als dedizierte DJ-Workstation unter Linux. Ziel war es, alte Hardware nachhaltig zu nutzen und eine stabile Umgebung für Mixxx zu schaffen. Die Hardware: Notebook: Alienware m17x (Core 2 Duo, 4GB RAM, SSD) OS: KDE Neon mit Low-Latency-Kernel (6.8.0) Software: Mixxx 2.4 Audio-Interface: Günstiges USB-Audio-Device für den Master-Ausgang Das Problem: Mixxx verweigerte unter ALSA den Dienst mit der Fehlermeldung: Error opening "USB Audio Device (hw:1,0)" - Invalid sample rate Die Analyse über /proc/asound/card1/stream0 zeigte die Ursache: Das USB-Gerät unterstützt ausschließlich 46875 Hz – eine für Audio-Interfaces sehr unübliche Rate, die weder 44100 Hz noch 48000 Hz entspricht. Der direkte Zugriff über hw:CARD=Device,DEV=0 schlug fehl. Die Lösung: Die Rettung war die Aktivierung der ALSA-Plug-Erweiterung über PipeWire/ALSA, die eine automatische Sample-Rate-Konvertierung erlaubt. Starten Sie Mixxx nicht direkt, sondern setzen Sie zuvor die Umgebungsvariable: export PA_ALSA_PLUGHW=1 mixxx Damit Mixxx auch dauerhaft korrekt startet (z.B. über das KDE-Menü), habe ich den Starter wie folgt angepasst: bash -c "export PA_ALSA_PLUGHW=1; mixxx" Ergebnis: ✅ Master-Ausgabe über das USB-Device funktioniert stabil. ✅ Kopfhörer-Vorhören (C-Media USB Headphone Set) läuft parallel. ✅ Das System läuft trotz des Alters der Hardware (2008) flüssig und mit geringer Latenz. Die vollständige Dokumentation inklusive Fotos des Umbaus, der genauen Kernel-Einstellungen und der Konfiguration findet ihr in meinem Open-Source-Repository: 👉 [ https://github.com/qrishii/DJ-Installationen ] Ich hoffe, diese Lösung hilft anderen, die ähnliche Probleme mit exotischen USB-Audio-Raten unter Linux haben! das Leben ist lustig

2026-08-01 原文 →
AI 资讯

Deploying ImgProxy – Process, Resize, Convert Images on the Fly

ImgProxy is an open-source image-processing server — resize, convert, and transform images on the fly via URL parameters, ideal as a caching layer in front of a CDN or web app. This guide builds ImgProxy from source on Ubuntu, runs it as a systemd service behind Nginx with TLS, walks through its URL processing options, and secures it with signed URLs. Prerequisites: an Ubuntu server, a domain A record (e.g. imgproxy.example.com ), non-root sudo user. Install ImgProxy ImgProxy uses libvips for image processing; this builds it from source with Go. $ sudo add-apt-repository ppa:dhor/myway $ sudo apt update $ sudo apt install libvips-dev -y $ sudo snap install --classic --channel = latest/stable go $ git clone https://github.com/imgproxy/imgproxy.git $ cd imgproxy $ sudo CGO_LDFLAGS_ALLOW = "-s|-w" go build -o /usr/local/bin/imgproxy Create the environment config: $ sudo touch /usr/local/bin/imgproxy.env $ sudo nano /usr/local/bin/imgproxy.env IMGPROXY_BIND = :8080 IMGPROXY_NETWORK = tcp IMGPROXY_READ_TIMEOUT = 10 IMGPROXY_WRITE_TIMEOUT = 10 IMGPROXY_WORKERS = 2 IMGPROXY_REQUESTS_QUEUE_SIZE = 0 IMGPROXY_QUALITY = 100 IMGPROXY_PREFERRED_FORMATS = webp,jpeg,png,gif,avif IMGPROXY_LOG_FORMAT = "pretty" IMGPROXY_LOG_LEVEL = "INFO" IMGPROXY_WATERMARK_URL = https://example.com/watermark.png IMGPROXY_WATERMARK_OPACITY = 1 Key settings: IMGPROXY_WORKERS should be ~2× your vCPU count; IMGPROXY_REQUESTS_QUEUE_SIZE=0 means unlimited queueing; IMGPROXY_WATERMARK_URL points at whatever image you want overlaid when watermarking is enabled. Point ImgProxy at the config and test: $ export IMGPROXY_ENV_LOCAL_FILE_PATH = /usr/local/bin/imgproxy.env $ cd $ imgproxy WARNING [2024-05-28T00:40:42Z] No keys defined, so signature checking is disabled WARNING [2024-05-28T00:40:42Z] No salts defined, so signature checking is disabled INFO [2024-05-28T00:40:42Z] Starting server at :8080 Stop it with Ctrl+C once verified, then set it up as a service. Run ImgProxy as a systemd Service $ sudo useradd

2026-07-31 原文 →
AI 资讯

Deploying code-server for VS Code on Ubuntu 24.04

code-server is the open-source project that runs full VS Code including extensions, integrated terminal, Git, IntelliSense — on a remote server, accessible from any browser. This guide deploys it on Ubuntu 24.04 with Docker Compose, fronted by Traefik for automatic HTTPS. Prerequisites: an Ubuntu 24.04 server (1GB RAM / 2 vCPU minimum), a domain A record (e.g. code.example.com ), Docker and Docker Compose installed. Set Up the Project $ mkdir -p ~/vscode-server/ { project,config,local,letsencrypt } $ cd ~/vscode-server project — your editable workspace config — code-server settings/extensions local — user-specific data letsencrypt — Traefik's ACME certificate storage Find your UID/GID and add yourself to the docker group: $ id $USER $ sudo usermod -aG docker $USER Write the Compose File $ nano docker-compose.yml services : code-server : image : codercom/code-server:latest container_name : code-server user : " UID:GID" # Replace with your user's UID and GID environment : - PASSWORD=SECURE_PASSWORD # Replace with a strong password - DOCKER_USER=LINUXUSER # Replace with your username volumes : - ./project:/home/coder/project - ./config:/home/coder/.config - ./local:/home/coder/.local networks : - internal restart : unless-stopped labels : - " traefik.enable=true" - " traefik.http.routers.code-server.rule=Host(`CODE.EXAMPLE.COM`)" # Replace with your domain name - " traefik.http.routers.code-server.entrypoints=websecure" - " traefik.http.routers.code-server.tls.certresolver=myresolver" - " traefik.http.services.code-server.loadbalancer.server.port=8080" traefik : image : traefik:latest container_name : traefik ports : - " 80:80" - " 443:443" volumes : - /var/run/docker.sock:/var/run/docker.sock:ro - ./letsencrypt:/letsencrypt command : - " --providers.docker=true" - " --providers.docker.exposedbydefault=false" - " --providers.docker.network=internal" - " --entrypoints.web.address=:80" - " --entrypoints.websecure.address=:443" - " --entrypoints.web.http.redirections.entr

2026-07-31 原文 →
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Deploying Gradio on Ubuntu 22.04

Gradio is a Python library for wrapping any ML model in a web interface, ready to deploy and scale as an app. This guide builds a GFPGAN-powered face-restoration demo with Gradio on Ubuntu 22.04, runs it as a systemd service, and exposes it through Nginx with TLS. Prerequisites: a GPU-enabled Ubuntu 22.04 server, a domain A record (e.g. gradio.example.com ), non-root sudo access, Nginx installed. Set Up the Server 1. Install dependencies: $ pip3 install realesrgan gfpgan basicsr gradio realesrgan — background restoration gfpgan — face restoration basicsr — provides RRDBNet , the super-resolution architecture GFPGAN relies on gradio — the web interface 2. GFPGAN's pandas dependency needs jinja2 >= 3.1.2: $ pip show jinja2 Upgrade if it's older: $ pip install --upgrade jinja2 3. Create the project directory: $ sudo mkdir -p /opt/gradio-webapp/ $ sudo chown -R : $( id -gn ) /opt/gradio-webapp/ $ sudo chmod -R 775 /opt/gradio-webapp/ Build the Gradio App Uploads a face image and returns two enhanced outputs. $ cd /opt/gradio-webapp/ $ nano app.py import gradio as gr from gfpgan import GFPGANer from basicsr.archs.rrdbnet_arch import RRDBNet from realesrgan import RealESRGANer import numpy as np import cv2 import requests def enhance_image ( input_image ): arch = ' clean ' model_name = ' GFPGANv1.4 ' gfpgan_checkpoint = ' https://github.com/TencentARC/GFPGAN/releases/download/v1.3.4/GFPGANv1.4.pth ' realersgan_checkpoint = ' https://github.com/xinntao/Real-ESRGAN/releases/download/v0.2.1/RealESRGAN_x2plus.pth ' rrdbnet = RRDBNet ( num_in_ch = 3 , num_out_ch = 3 , num_feat = 64 , num_block = 23 , num_grow_ch = 32 , scale = 2 ) bg_upsampler = RealESRGANer ( scale = 2 , model_path = realersgan_checkpoint , model = rrdbnet , tile = 400 , tile_pad = 10 , pre_pad = 0 , half = True ) restorer = GFPGANer ( model_path = gfpgan_checkpoint , upscale = 2 , arch = arch , channel_multiplier = 2 , bg_upsampler = bg_upsampler ) input_image = input_image . astype ( np . uint8 ) cropped_fa

2026-07-31 原文 →
AI 资讯

Installing Nginx UI – An Open-Source WebUI for Nginx

Nginx UI is an open-source web GUI for managing Nginx, single-node or clustered, with real-time stats, automatic Let's Encrypt TLS, performance monitoring, and even LLM-assisted config editing. This guide installs it on Ubuntu 24.04, puts it behind a reverse proxy with TLS, sets up ACME certificate management, and creates a virtual host through the dashboard. Prerequisites: an Ubuntu 24.04 server, non-root sudo user, a domain A record (e.g. nginx-ui.example.com ), Docker installed if you choose that install path. $ sudo apt update $ sudo apt install nginx -y Pick one of the two install methods below. Option A: Install via Script Runs Nginx UI as a system service, managing the host's Nginx directly. $ curl -O https://cloud.nginxui.com/install.sh $ sudo bash install.sh install $ nginx-ui --version $ sudo systemctl start nginx-ui $ sudo systemctl status nginx-ui Option B: Install via Docker Runs as a container — you won't be able to edit the host's Nginx configs directly through it. $ mkdir -p ~/nginx-ui-docker $ cd ~/nginx-ui-docker $ sudo mkdir -p /opt/nginx-ui/nginx $ sudo mkdir -p /opt/nginx-ui/config $ sudo mkdir -p /opt/nginx-ui/www $ nano docker-compose.yml version : ' 3.8' services : nginx-ui : image : uozi/nginx-ui:latest container_name : nginx-ui restart : always environment : - TZ=UTC volumes : - /opt/nginx-ui/nginx:/etc/nginx - /opt/nginx-ui/config:/etc/nginx-ui - /opt/nginx-ui/www:/var/www ports : - " 127.0.0.1:9000:80" networks : - nginx-ui-net networks : nginx-ui-net : driver : bridge $ sudo docker compose up -d $ sudo docker compose ps $ curl -X GET http://localhost:9000 Configure the Reverse Proxy Nginx UI listens on localhost:9000 . Put it behind a public vhost with WebSocket support (needed for live stats/terminal): $ cd /etc/nginx/sites-available $ sudo nano nginx-ui.conf map $http_upgrade $connection_upgrade { default upgrade ; '' close ; } server { listen 80 ; listen [::]:80 ; server_name nginx-ui.example.com ; location / { proxy_set_header Host $

2026-07-31 原文 →
AI 资讯

Installing Ghost Blogging Platform on Ubuntu 24.04

Ghost is an open-source publishing platform with built-in newsletters, memberships, subscriptions, ActivityPub federation, and Tinybird-powered web analytics. This guide covers two install paths on Ubuntu 24.04: Ghost-CLI for a traditional host install, and Docker Compose for a containerized deployment with analytics. Prerequisites: an Ubuntu 24.04 server, non-root sudo user, a domain A record (e.g. ghost.example.com ). Option A: Install with Ghost-CLI Install Node.js Ghost requires Node v22 LTS — check compatible versions before installing elsewhere. $ curl -fsSL https://deb.nodesource.com/setup_22.x -o nodesource_setup.sh $ sudo -E bash nodesource_setup.sh $ sudo apt install -y nodejs $ node -v Install and Configure MySQL $ sudo apt install -y mysql-server $ mysql --version $ sudo mysql_secure_installation Walk through the prompts: enable password validation ( y ), pick strong policy ( 2 ), remove anonymous users ( y ), restrict root to localhost ( y ), drop the test database ( y ), reload privileges ( y ). $ sudo mysql mysql > CREATE DATABASE ghost_db ; mysql > CREATE USER 'ghostuser' @ 'localhost' IDENTIFIED BY 'Your_password2!' ; mysql > GRANT ALL PRIVILEGES ON ghost_db . * TO 'ghostuser' @ 'localhost' ; mysql > FLUSH PRIVILEGES ; mysql > EXIT ; Install Nginx $ sudo apt install -y nginx $ sudo ufw allow 'Nginx Full' $ sudo systemctl status nginx Install Ghost $ sudo npm install ghost-cli@latest -g $ sudo mkdir -p /var/www/html/ghost $ sudo chown $USER : $USER /var/www/html/ghost $ sudo chmod 775 /var/www/html/ghost $ cd /var/www/html/ghost $ ghost install The installer prompts for: Blog URL : https://ghost.example.com MySQL hostname : localhost MySQL username/password/database : from the setup above Set up Nginx? : y Set up SSL? : y (installs acme.sh ) Email for SSL : your address Set up Systemd? : y Start Ghost? : y Manage the Config $ nano /var/www/html/ghost/config.production.json $ cd /var/www/html/ghost $ ghost restart Or via systemd (replace ghost-example

2026-07-31 原文 →
AI 资讯

Deploying phpBB on Ubuntu 22.04

phpBB is an open-source forum application for building discussion communities — user registration, moderation, permissions, and multiple boards in one interface. This guide deploys phpBB on Ubuntu 22.04 with an external MySQL database, an Apache virtual host, and Let's Encrypt TLS. Prerequisites: an Ubuntu 22.04 server with the LAMP stack installed, non-root sudo user, an external MySQL database, a subdomain A record (e.g. phpbb.example.com ). Create the Database $ mysql -h your-db-host -P 3306 -u dbadmin -p mysql > CREATE DATABASE phpbbdb ; mysql > USE phpbbdb ; mysql > CREATE USER 'phpbbuser' @ 'localhost' IDENTIFIED BY 'securepassword' ; mysql > GRANT ALL ON phpbbdb . * to 'phpbbuser' @ 'localhost' ; mysql > FLUSH PRIVILEGES ; mysql > EXIT ; Install phpBB 1. Install PHP modules: $ sudo apt install php-mysql php-xml php-mbstring -y 2. Download and extract — check the releases page for the current version: $ wget -O phpbb.zip https://download.phpbb.com/pub/release/3.3/3.3.11/phpBB-3.3.11.zip $ unzip phpbb.zip $ sudo mv phpBB3 /var/www/html/phpbb 3. Set ownership and permissions: $ sudo chown -R www-data:www-data /var/www/html/phpbb $ sudo find /var/www/html/phpbb -type d -exec chmod 755 {} \; $ sudo find /var/www/html/phpbb -type f -exec chmod 644 {} \; Configure Apache $ sudo nano /etc/apache2/sites-available/phpbb.conf < VirtualHost *:80 > ServerAdmin admin@example.com DocumentRoot /var/www/html/phpbb ServerName phpbb.example.com < Directory /var/www/html/phpbb > Options FollowSymlinks AllowOverride All Require all granted </ Directory > ErrorLog ${APACHE_LOG_DIR}/phpbb_error.log CustomLog ${APACHE_LOG_DIR}/phpbb_access.log combined </ VirtualHost > $ sudo a2ensite phpbb $ sudo a2enmod rewrite $ sudo systemctl restart apache2 Secure phpBB 1. Firewall: $ sudo ufw status $ sudo ufw allow 22 && sudo ufw enable $ sudo ufw allow 80/tcp $ sudo ufw allow 443/tcp $ sudo ufw reload 2. TLS via Let's Encrypt: $ sudo apt install snapd -y $ sudo snap install --classic certbot

2026-07-31 原文 →
AI 资讯

Deploying a PostgreSQL Cluster with Patroni and HAProxy on Ubuntu 24.04

A Patroni cluster needs an odd number of nodes to maintain quorum — with 3 nodes, losing 1 still leaves a majority, so the cluster keeps running. This guide builds a 3-node PostgreSQL cluster on Ubuntu 24.04 with Patroni handling replication and automatic failover, etcd as the coordination store, and HAProxy load-balancing client connections — all secured with TLS. Prerequisites: three Ubuntu 24.04 servers (2 vCPU / 4GB RAM minimum) with PostgreSQL installed, non-root sudo access, and a domain with three A records: node1.example.com , node2.example.com , node3.example.com . Replace these placeholders with your actual subdomains throughout. Install Dependencies Run on all three nodes unless noted otherwise. 1. Install packages: $ sudo apt update $ sudo apt install haproxy certbot pipx -y $ sudo pip3 install --break-system-packages 'patroni[etcd3]' psycopg2-binary psycopg 2. Install etcd: $ wget https://github.com/etcd-io/etcd/releases/download/v3.6.4/etcd-v3.6.4-linux-amd64.tar.gz $ tar -xvf etcd-v3.6.4-linux-amd64.tar.gz $ sudo mv etcd-v3.6.4-linux-amd64/etcd etcd-v3.6.4-linux-amd64/etcdctl /usr/local/bin/ 3. Open firewall ports — 80 (Certbot), 2379/2380 (etcd), 5432/5433 (PostgreSQL + Patroni-managed PostgreSQL), 8008/8009 (Patroni REST API): $ sudo ufw allow 80,2379,2380,5432,5433,8008,8009/tcp $ sudo ufw reload $ sudo ufw status Configure SSL Certificates 1. Request a certificate per node (run on each node for its own subdomain): $ sudo certbot certonly --standalone -d node1.example.com -m admin@example.com --agree-tos --no-eff 2. Create a cert-prep script on each node (set HOSTNAME to that node's subdomain): $ sudo nano /usr/local/bin/prepare-ssl-certs.sh #!/bin/bash HOSTNAME = "node1.example.com" # Update for each node CERT_DIR = "/etc/letsencrypt/live/ $HOSTNAME " ARCHIVE_DIR = "/etc/letsencrypt/archive/ $HOSTNAME " getent group ssl-users > /dev/null || sudo groupadd ssl-users for user in etcd patroni haproxy postgres ; do if ! id " $user " > /dev/null 2>&1 &&

2026-07-31 原文 →
AI 资讯

Deploying Laravel with Nginx on Ubuntu 24.04

Laravel is a popular PHP framework with routing, authentication, and database management built in. This guide deploys a Laravel app behind Nginx on Ubuntu 24.04, wires it to MySQL, secures it with Let's Encrypt, and builds a small dashboard that queries live data. Prerequisites: Ubuntu 24.04 with Nginx and MySQL installed, a non-root sudo user, a domain A record (e.g. app.example.com ). Create the Database $ sudo mysql mysql > CREATE DATABASE laravel_demo ; mysql > CREATE USER 'laravel_user' @ 'localhost' IDENTIFIED WITH mysql_native_password BY 'secure_password' ; mysql > GRANT ALL ON laravel_demo . * TO 'laravel_user' @ 'localhost' ; mysql > FLUSH PRIVILEGES ; mysql > EXIT ; Seed a demo table to query later: $ mysql -u laravel_user -p mysql > USE laravel_demo ; mysql > CREATE TABLE server_stats ( id INT AUTO_INCREMENT , server_name VARCHAR ( 255 ), region VARCHAR ( 255 ), cpu_usage DECIMAL ( 5 , 2 ), memory_usage DECIMAL ( 5 , 2 ), status ENUM ( 'active' , 'maintenance' , 'offline' ), last_updated TIMESTAMP DEFAULT CURRENT_TIMESTAMP , PRIMARY KEY ( id ) ); mysql > INSERT INTO server_stats ( server_name , region , cpu_usage , memory_usage , status ) VALUES ( 'app-01' , 'us-east' , 24 . 50 , 45 . 30 , 'active' ), ( 'db-01' , 'eu-west' , 12 . 75 , 78 . 20 , 'active' ), ( 'web-01' , 'ap-south' , 65 . 80 , 89 . 50 , 'active' ); mysql > EXIT ; Install Composer and PHP Extensions $ sudo apt update $ sudo apt install composer php php-curl php-fpm php-bcmath php-json php-mysql php-mbstring php-xml php-tokenizer php-zip -y $ composer --version $ php --version $ sudo systemctl restart php8.3-fpm php-fpm runs PHP as a service Nginx can talk to; php-mysql / php-mbstring / php-xml / php-tokenizer / php-zip cover Laravel's runtime requirements. Create the Laravel Project $ cd ~ $ composer create-project --prefer-dist laravel/laravel laravel-demo $ cd laravel-demo $ php artisan key:generate Edit .env : $ nano .env APP_NAME = laravel-demo APP_ENV = development APP_KEY = base64:APP

2026-07-31 原文 →
AI 资讯

Article: Virtual Threads After JDK 24: What Changed for Production Java

JDK 24 removed the monitor-related carrier-thread pinning that stalled Netflix and similar teams on Java 21. What has replaced it on JDK 25 LTS is downstream-resource saturation: The bottleneck moved and now demands explicit bounding in application code. This article maps the failure modes that surface after virtual-thread adoption and gives a practical sequence backed by a public benchmark. By Sandeep Bharadwaj

2026-07-31 原文 →
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Why NVIDIA Open-Sourced Its Linux GPU Kernel Modules

The biggest reason NVIDIA began providing GPL-licensed kernel modules is that its driver architecture evolved to the point where Linux integration, distribution, and maintenance could be greatly simplified while keeping the GPU's critical intellectual property in firmware and user-space components . To be precise, NVIDIA did not open-source its entire driver stack. The components that became open are primarily the following Linux kernel modules: nvidia.ko nvidia-drm.ko nvidia-uvm.ko nvidia-modeset.ko User-space components such as CUDA, OpenGL, Vulkan, and the GSP firmware remain proprietary. ( NVIDIA Developer ) 1. To make integration with Linux distributions easier Previously, NVIDIA's proprietary kernel modules had to be built, signed, and distributed separately from the Linux kernel. A DKMS-based workflow, which rebuilds modules after every kernel update, commonly led to problems such as: Kernel modules failing to build after kernel updates Unsigned modules being blocked by Secure Boot Linux distributions having difficulty maintaining the driver as an official package Increased complexity when integrating with custom kernels or cloud environments By publishing the source code, distributions such as Ubuntu, Red Hat, and SUSE can integrate NVIDIA's kernel modules into their own packaging, signing, and update infrastructure much more easily. NVIDIA itself cites tighter OS integration and simpler signing and distribution as key motivations. ( NVIDIA Developer ) 2. To improve debugging and security review Kernel modules interact with deep parts of the operating system, including memory management, interrupts, inter-process synchronization, PCI Express, and display subsystems. With the source code available, Linux distribution developers and enterprise users can: Trace where execution stops inside the kernel Analyze interactions between GPU events and workloads Fix incompatibilities with custom kernels Review security-related issues Submit patches to NVIDIA NVIDIA stat

2026-07-31 原文 →
AI 资讯

File Compression in Linux Explained Simply (tar, gzip, zip & unzip)

Working with files in Linux isn't just about creating and editing them. Sometimes you need to: Archive multiple files into one Compress files to save disk space Share files with others Create backups Linux provides several tools for this, each with a different purpose. Let's simplify them. What is File Compression? File compression reduces the size of a file. Benefits: Saves disk space Faster file transfers Easier backups Reduces bandwidth usage Example: A 100 MB log file might become a much smaller compressed file, depending on its contents. Archive vs Compression Many beginners think they're the same. They are not. Archive Combines multiple files into a single file. Example: photos/ docs/ notes.txt ↓ backup.tar Compression Reduces the size of a file. Example: backup.tar ↓ backup.tar.gz 👉 tar archives files. gzip compresses them. 1. Create an Archive with tar tar -cvf backup.tar Documents/ #Create an archive tar -tvf backup.tar #View archive contents tar -xvf backup.tar #Extract an archive Options: c → Create v → Verbose (show progress) f → File name x → Extract Best for: Backups Bundling multiple files Moving folders 2. Compress with gzip Compress a file: gzip file.txt # Creates file.txt.gz # Result file.txt.gz gunzip file.txt.gz # decompress gzip -k file.txt # Keep original file Best for: Log files Large text files Saving disk space 3. Archive and Compress Together Most common command: # Create compressed archive tar -czvf backup.tar.gz Documents/ # Extract tar -xzvf backup.tar.gz Options: z → Use gzip compression 👉 This is one of the most common backup commands in Linux. 4. Working with ZIP Files # Create ZIP zip -r project.zip project/ # Extract unzip project.zip # List contents unzip -l project.zip Best for: Sharing files with Windows users Cross-platform compatibility 5. Compare the Tools Tool Purpose Best For tar Archive files Backups gzip Compress files Saving space tar + gzip Archive and compress Linux backups zip Archive and compress Sharing files across

2026-07-30 原文 →
AI 资讯

The Great Ubuntu Blackout: My 3-Hour Journey to Fix the Darkness

Introduction It was a perfectly normal day. I opened my laptop, ready to get some work done, and then... BAM. A black screen. Not a gentle fade to black, but more like my computer shouting, "I’ve had enough of your crap!" The same operating system that had been working perfectly just five hours earlier had suddenly decided it had had enough of life. I wasn't too worried though. After all, I had ChatGPT on my side. Three hours later... Yeah... my confidence crumbled faster than my phone battery at 2%. What followed was a three-hour rabbit hole involving NVIDIA drivers, multiple Linux kernels, Secure Boot, DKMS, Xorg, GDM, journalctl , systemd , and more terminal commands than I'd like to admit. Somehow, against all odds (and probably a little divine intervention), we managed to fix it. And honestly? I enjoyed every minute of the chaos. It was like a wild adventure—except with more curse words and less danger. So I decided to document the entire debugging journey—not just because it might help someone who runs into the same issue, but also because I deserve a little sympathy after spending three hours arguing with my laptop. (And if the solution seems painfully obvious to you... please let me enjoy my victory. Don't take this away from me.😤 The Problem After rebooting my laptop, I was greeted with just a black screen. No login screen, no desktop… just nothing.** At first, I tried to enter TTY using Ctrl + Alt + F3, but that wasn’t working either. Since I wasn’t able to reach TTY directly, I had to take a different route. By editing the GRUB boot entry and booting into multi-user.target , I forced Linux to start in text-only mode, giving me access to a terminal.** For this, I edited the GRUB boot entry and appended systemd.unit=multi-user.target to the end of the kernel command line (after quiet splash ). That was the first breakthrough, though. The operating system wasn’t completely dead… only the graphical interface was failing to wake up. First Clues and Initial Ass

2026-07-30 原文 →
AI 资讯

Mes premiers pas avec Linux et Git : comment j'ai préparé ma réunion CloudHer

Il y a quelques jours, j'ai réalisé un truc qui m'a un peu stressée : ma réunion de la semaine 4 avec ma mentor Endah Bongo approchait, et le programme prévoyait Linux et Git. Sauf que... je ne maîtrisais pas encore les différentes commandes utilisées. Plutôt que de paniquer, j'ai décidé de prendre les choses en main et de tout pratiquer en direct, une commande à la fois, jusqu'à ce que ça fasse sens. Voici ce que j'ai appris, dans l'ordre où je l'ai découvert. Se repérer dans un terminal Linux La toute première chose à comprendre avec Linux, c'est qu'on est toujours "quelque part" dans une arborescence de dossiers. Trois commandes suffisent pour s'orienter : pwd ( print working directory ) affiche l'endroit exact où on se trouve ls liste le contenu du dossier courant cd permet de se déplacer d'un dossier à l'autre Avec cd ~ , on revient direct dans son dossier personnel. Une astuce toute simple, mais qui change la vie quand on découvre le terminal. Créer et organiser des fichiers Une fois qu'on sait se déplacer, l'étape suivante c'est de manipuler des fichiers et dossiers : mkdir crée un nouveau dossier touch crée un fichier vide ls -la permet de tout voir en détail, y compris les fichiers cachés et les permissions C'est là que j'ai découvert les permissions Linux (ce fameux -rw-r--r-- qu'on voit à côté de chaque fichier), qui déterminent qui peut lire, écrire ou exécuter un fichier. Entrer dans le monde de Git Une fois les bases Linux en poche, place à Git. Première étape : configurer son identité, une seule fois pour toutes les utilisations futures. git config --global user.name "Ton nom" git config --global user.email "ton_email@exemple.com" Ensuite, j'ai transformé mon dossier de test en dépôt Git avec git init , puis j'ai découvert le cycle de base que tout développeur utilise au quotidien : Modifier un fichier git add pour l'ajouter à la zone de préparation (staging) git commit -m "message" pour valider les changements Entre les deux, git status est devenu mo

2026-07-29 原文 →