Articles

167 entries match these filters

• 0281 What is a package manager? A package manager is a tool that installs, updates and removes software for you and keeps track of what depends on what. Beginner · Explains an idea · Any system Article Packages & updates 15 Oct 2026
• 0266 What is a port? A port is a numbered door on a computer that lets one machine run many network services at the same time. Beginner · Explains an idea · Any system Article DNS, IP addresses & ports 15 Oct 2026
• 0282 What is a dependency? A dependency is another piece of software your program needs to work, such as a library it imports. Beginner · Explains an idea · Any system Article Environments & packages 15 Oct 2026
• 0267 What is an API? An API is a set of rules that lets one program ask another program for data or actions without knowing how it… Beginner · Explains an idea · Any system Article Making requests 15 Oct 2026
• 0283 What is a virtual environment? A virtual environment is a private folder of Python packages for one project, so different projects never clash. Beginner · Explains an idea · Any system Article Environments & packages 15 Oct 2026
• 0268 What is a container? A container is a lightweight box that packs a program with everything it needs so it runs the same on any computer. Beginner · Explains an idea · Any system Article Docker basics 15 Oct 2026
• 0284 What is a shell? A shell is the program that reads the commands you type and tells the operating system to run them. Beginner · Explains an idea · Any system Article Basics 15 Oct 2026
• 0269 What is a commit? A commit is a saved snapshot of your project in Git, with a message explaining what changed and why. Beginner · Explains an idea · Any system Article Branching & rebasing 15 Oct 2026
• 0285 What is a terminal? A terminal is the window where you type commands; the shell inside it does the actual work. Beginner · Explains an idea · Any system Article Basics 15 Oct 2026
• 0270 What is a branch? A branch is a separate line of work in Git, so you can try changes without touching the main version of the… Beginner · Explains an idea · Any system Article Branching & rebasing 15 Oct 2026
• 0286 What is PATH? PATH is the list of folders your shell searches to find a program when you type its name. Beginner · Explains an idea · Any system Article Basics 15 Oct 2026
• 0271 What is a merge conflict? A merge conflict happens when two branches changed the same lines and Git needs a human to decide which version wins. Beginner · Explains an idea · Any system Article Branching & rebasing 15 Oct 2026
• 0287 What is an environment variable? An environment variable is a named value the operating system passes to programs, such as settings or secrets. Beginner · Explains an idea · Any system Article Basics 15 Oct 2026
• 0272 What is a virtual machine? A virtual machine is a complete computer made of software, running inside another computer with its own operating system. Beginner · Explains an idea · Any system Article Basics 15 Oct 2026
• 0288 What is a daemon or service? A daemon or service is a program that runs in the background all the time, waiting to do its job without a… Beginner · Explains an idea · Any system Article Services & systemd 15 Oct 2026
• 0273 What is a hypervisor? A hypervisor is the software layer that creates and runs virtual machines and shares the real hardware between them. Beginner · Explains an idea · Any system Article Basics 15 Oct 2026
• 0274 What is DNS? DNS is the internet's phone book: it turns names like example.com into the IP addresses computers actually use. Beginner · Explains an idea · Any system Article DNS, IP addresses & ports 15 Oct 2026
• 0275 What is an IP address? An IP address is the unique number that identifies a device on a network so data knows where to go. Beginner · Explains an idea · Any system Article DNS, IP addresses & ports 15 Oct 2026
• 0276 What is SSH? SSH is a secure way to open a command line on another computer over the network, with everything encrypted. Beginner · Explains an idea · Any system Article SSH 15 Oct 2026
• 0277 What is TLS? TLS is the encryption layer that puts the S in HTTPS, protecting data between your browser and a server. Beginner · Explains an idea · Any system Article TLS & certificates 15 Oct 2026
• 0278 What is a certificate? A certificate is a digital ID card that proves a website or server is genuine, issued by a trusted authority. Beginner · Explains an idea · Any system Article TLS & certificates 15 Oct 2026
• 0261 Build a Python command-line to-do app: from empty folder to installable command Create a small to-do tool in Python with argparse and JSON storage, test it with pytest and package it with pyproject.toml so… Beginner · Guided project · Any system Article Environments & packages · Files & automation · Testing 15 Oct 2026
• 0262 Make your first pull request: Git and GitHub from first commit to merged change A complete beginner's path through Git and GitHub: set up Git, make commits, ignore files, use branches, push to GitHub, open a… Beginner · Guided project · Any system Article Branching & rebasing · Pull requests · Setup 15 Oct 2026
• 0260 Design and build a library database in SQLite: tables, keys, joins, reports and backups Model books, members and loans, create tables with keys and constraints, load sample data, write join and aggregate reports, add indexes checked… Beginner · Guided project · Any system Article Joins · Queries 15 Oct 2026
• 0232 mongosh cheat sheet: CRUD, indexes and explain() The mongosh commands you use every day: switching databases, inserting, querying, updating and deleting documents, creating indexes and checking a query plan… Beginner · Cheat sheet · Any system Article Basics 15 Oct 2026
• 0236 Redis data types and commands: a quick reference Redis stores values under keys, and each value has a type: string, hash, list, set, sorted set or stream. The essential commands… Beginner · Cheat sheet · Any system Article Basics 15 Oct 2026
• 0241 Choosing a database: relational, document or key-value Relational databases, document stores like MongoDB and key-value stores like Redis each fit different jobs. An honest look at what each does… Beginner · Explains an idea · Any system Article Choosing a database · Database operations 15 Oct 2026
• 0247 Build a Proxmox VE home lab: from bare metal to your first restored backup Install Proxmox VE on one spare machine, switch to the free update repository, create a VM and an LXC container, then schedule… Beginner · Guided project · Linux Article Backup & restore · Installation & first steps · VMs & containers 15 Oct 2026
• 0248 Run your first KVM virtual machine with libvirt and virt-install Turn a Linux desktop or server into a KVM host: check CPU support, install libvirt, use the default NAT network, create a… Beginner · Guided project · Linux Article Basics 15 Oct 2026
• 0249 Set up and harden a fresh Linux server in one afternoon Take a new Ubuntu, Debian or Rocky/Alma server from first login to a safer baseline: sudo admin, SSH keys only, firewall, automatic… Beginner · Guided project · Linux Article Networking & firewalls · Packages & updates · Users, sudo & hardening 15 Oct 2026
• 0251 Learn Kubernetes on your laptop with kind: from first cluster to Ingress Build a throwaway Kubernetes cluster in Docker with kind, deploy a web app with config, secrets and probes, scale it, roll out… Beginner · Guided project · Linux, macOS, Windows Article Concepts · Workloads & services 15 Oct 2026
• 0256 Manage infrastructure as code with Terraform: from first file to plans on pull requests Learn the full Terraform workflow without a cloud account: variables, a module, outputs, state, plan, apply and destroy, a backend for shared… Beginner · Guided project · Linux, macOS, Windows Article GitHub Actions · Terraform 15 Oct 2026
• 0202 Back up and restore PostgreSQL with pg_dump, pg_restore and pg_dumpall Make logical backups of one database with pg_dump, of roles and the whole cluster with pg_dumpall, and restore them with pg_restore or… Beginner · Step by step · Linux Article Backup & restore 15 Oct 2026
• 0211 Fix: psql connection to server on socket /var/run/postgresql/.s.PGSQL.5432 failed psql tried the local Unix socket and found nothing there. The server is not running, listens on another port, or uses a… Beginner · Fixes an error · Linux Article Install & connect 15 Oct 2026
• 0214 MySQL users and privileges: CREATE USER, GRANT and authentication plugins A MySQL account is a user name plus the host it connects from. You create it with CREATE USER, give it rights… Beginner · Step by step · Linux Article Administration · Security & access 15 Oct 2026
• 0215 mysql command-line client cheat sheet The connection options, built-in commands and everyday SQL you need in the mysql (and mariadb) command-line client, on one page. Beginner · Cheat sheet · Any system Article Administration · Queries 15 Oct 2026
• 0220 Fix: ERROR 1045 (28000): Access denied for user ‘appuser’@’localhost’ (using password: YES) The server rejected the user, host and password combination. Usually it is a wrong password, a host part that does not match,… Beginner · Fixes an error · Linux Article Administration · Security & access 15 Oct 2026
• 0221 Oracle Database basics: instance vs database, CDB and PDB An Oracle instance is memory and processes; the database is the files on disk. Since 21c every database is a container database… Beginner · Explains an idea · Linux, Windows Article Concepts & tools 15 Oct 2026
• 0231 MongoDB documents and collections compared with SQL tables MongoDB stores data as JSON-like documents grouped in collections instead of rows in tables. This explains the model, the _id field, embedding… Beginner · Explains an idea · Any system Article Basics · Choosing a database 15 Oct 2026
• 0199 psql meta-commands cheat sheet The backslash commands you use every day in psql: connecting, listing databases, tables and roles, describing objects, timing queries, expanded output and… Beginner · Cheat sheet · Any system Article Install & connect · Roles & administration 15 Oct 2026