Articles

49 entries match these filters

0001 Virtual environments with venv A virtual environment is a private folder of Python packages for one project, so projects never fight over versions. Create one with… Beginner · Concept · Any system Article Environments & packages 15 Oct 2026
0004 Logging instead of print The logging module gives every message a level, a timestamp and a destination you can change without editing code. It is the… Intermediate · Concept · Any system Article Files & automation 15 Oct 2026
0005 Dataclasses in depth @dataclass writes __init__, __repr__ and __eq__ for classes that mainly hold data. Learn defaults, default_factory, frozen and ordered classes, __post_init__ validation, slots… Advanced · Concept · Any system Article Basics 15 Oct 2026
0016 let, const and var: variables and scope in JavaScript Use const by default, let when a value must change, and avoid var. The difference is about scope: where a variable is… Beginner · Concept · Any system Article Basics 15 Oct 2026
0018 Promises and async/await explained A promise is a placeholder for a value that arrives later. async/await lets you write code that waits for promises as if… Intermediate · Concept · Any system Article Async code 15 Oct 2026
0024 TypeScript basics: types, interfaces, unions and narrowing TypeScript adds type annotations to JavaScript and checks them before your code runs. These are the core ideas you need to read… Beginner · Concept · Any system Article Basics 15 Oct 2026
0033 The everyday Git workflow: status, add, commit, push, pull Git moves your changes through three places: the working folder, the staging area, and the commit history. These five commands, plus .gitignore… Beginner · Concept · Any system Article Housekeeping · Setup 15 Oct 2026
0034 Merging vs rebasing in Git Merge and rebase both bring commits from one branch into another. Merge keeps history exactly as it happened; rebase replays your commits… Intermediate · Concept · Any system Article Branching & rebasing 15 Oct 2026
0035 Undoing changes in Git: restore, reset, revert, and reflog Pick the undo command by where the mistake lives: in a file, in the staging area, in a local commit, or in… Intermediate · Concept · Any system Article Undoing changes 15 Oct 2026
0049 Pipes and redirection: connecting commands A pipe sends one command's output into another command, and redirection sends output to a file. Together they let small tools build… Beginner · Concept · Linux, macOS Article Basics · Text processing 15 Oct 2026
0050 File permissions: chmod, chown and what 755 means Every file has an owner, a group and read/write/execute permissions for three kinds of users. chmod changes the permissions and chown changes… Beginner · Concept · Linux, macOS Article Basics 15 Oct 2026
0051 Environment variables and PATH Environment variables are named settings that every program inherits from the shell. PATH is the one that tells the shell where to… Beginner · Concept · Linux, macOS Article Basics 15 Oct 2026
0055 Docker basics: images, containers and the commands you need An image is a read-only package of an app and its dependencies, and a container is a running instance of it. Learn… Beginner · Concept · Linux, macOS, Windows Article Docker basics 15 Oct 2026
0068 SQL joins explained: INNER, LEFT and finding rows with no match A join combines rows from two tables using a matching condition. INNER JOIN keeps only matches, LEFT JOIN keeps every row from… Intermediate · Concept · Any system Article Joins 15 Oct 2026
0069 NULL in SQL: why = NULL never matches and how to handle missing values NULL means "unknown", so comparisons with it are neither true nor false. Use IS NULL, COALESCE and careful aggregates to avoid rows… Intermediate · Concept · Any system Article Queries 15 Oct 2026
0070 Indexes and EXPLAIN: making SQL queries fast An index is a sorted lookup structure that lets the database jump to matching rows instead of reading the whole table. EXPLAIN… Advanced · Concept · Any system Article Indexes & performance 15 Oct 2026
0072 CSV vs JSON: choosing a format and avoiding the classic pitfalls CSV is a simple table of text; JSON holds nested, typed data. Both break in predictable ways: quoting, delimiters, encodings, numbers and… Beginner · Concept · Any system Article CSV & JSON 15 Oct 2026
0081 How an HTTP request works: methods, headers, and body An HTTP request is a short text message a client sends to a server: a method and path, some headers, and sometimes… Beginner · Concept · Any system Article Making requests 15 Oct 2026
0086 API authentication basics: API keys, Bearer tokens, and OAuth How APIs know who is calling: static API keys, Bearer tokens in the Authorization header, Basic auth, and a high-level tour of… Intermediate · Concept · Any system Article Authentication 15 Oct 2026
0087 CORS explained: why the browser blocks your request CORS is the browser rule that decides whether JavaScript on one origin may read a response from another. The server opts in… Intermediate · Concept · Browser Article Async code · Making requests 15 Oct 2026
0098 What Proxmox VE is: KVM virtual machines, LXC containers and a web UI Proxmox VE is an open source virtualization platform based on Debian. It runs KVM virtual machines and LXC containers and is managed… Beginner · Concept · Linux Article Basics · Installation & first steps 15 Oct 2026
0102 Proxmox VE storage types: local, LVM-thin, ZFS, NFS and Ceph Proxmox VE stores disks, ISOs, templates and backups in storage pools defined in /etc/pve/storage.cfg. Learn the main storage types, what local and… Intermediate · Concept · Linux Article Disks, LVM & filesystems · Storage 15 Oct 2026
0105 High availability in Proxmox VE: HA resources, fencing and affinity rules Proxmox VE HA restarts VMs and containers on another node when a node fails. Learn the requirements, how watchdog fencing protects your… Advanced · Concept · Linux Article Clusters & high availability 15 Oct 2026
0115 What is Oracle Private Cloud Appliance (PCA)? Hardware, enclaves and release lines Oracle Private Cloud Appliance is a factory-built rack of compute, storage and network hardware with its own cloud software. Release 3.x offers… Beginner · Concept · Linux Article Architecture & concepts 15 Oct 2026
0116 PCA 3.x Compute Enclave concepts: tenancies, compartments, VCNs, instances, images and shapes The PCA 3.x Compute Enclave uses OCI building blocks: a tenancy holds compartments, which hold networks, instances and storage. Instances are built… Beginner · Concept · Linux Article Architecture & concepts · Compute, networking & storage 15 Oct 2026
0122 PCA 3.x health monitoring and upgrade workflow overview How Private Cloud Appliance 3.x reports health (Grafana, Prometheus, Loki, platform health checks) and how appliance upgrades work: ISO images, an upgrade… Advanced · Concept · Linux Article Administration & monitoring 15 Oct 2026
0123 KVM vs QEMU vs libvirt: how Linux virtualization fits together KVM is the Linux kernel part that uses CPU virtualization extensions, QEMU is the program that emulates a full machine around it,… Beginner · Concept · Linux Article Basics 15 Oct 2026
0131 Kubernetes architecture: control plane, nodes, kubelet and etcd A Kubernetes cluster is a control plane that stores and decides the desired state, plus worker nodes that run your containers. This… Beginner · Concept · Linux Article Concepts 15 Oct 2026
0132 Pods, ReplicaSets and Deployments explained A Pod runs one or more containers together, a ReplicaSet keeps a fixed number of identical Pods alive, and a Deployment manages… Beginner · Concept · Linux Article Concepts · Workloads & services 15 Oct 2026
0133 Services and Ingress: exposing an app in Kubernetes A Service gives a changing set of Pods one stable address. ClusterIP is internal, NodePort and LoadBalancer reach outside, and an Ingress… Intermediate · Concept · Linux Article Ingress & networking 15 Oct 2026
0134 ConfigMaps and Secrets: configuration outside the image ConfigMaps hold plain settings and Secrets hold sensitive values, injected into Pods as environment variables or files. Secrets are only base64-encoded, not… Intermediate · Concept · Linux Article Config, secrets & storage 15 Oct 2026
0149 OpenShift vs Kubernetes vs OKD: what OpenShift adds OpenShift is Red Hat's Kubernetes platform and OKD is its community distribution. Both add projects, routes, builds, image streams, Operators and stricter… Beginner · Concept · Linux Article Concepts · Concepts 15 Oct 2026
0155 Security Context Constraints (SCC) and why root containers fail on OpenShift SCCs decide which user ID, capabilities and volumes a pod may use. Learn how restricted-v2 assigns random UIDs, how to see which… Advanced · Concept · Linux Article Cluster administration · Concepts 15 Oct 2026
0156 Operators, the software catalog (OperatorHub) and OLM on OpenShift Operators automate installing and running software on OpenShift. Learn the difference between cluster Operators and add-on Operators, and how OLM uses catalogs,… Intermediate · Concept · Linux Article Cluster administration · Concepts 15 Oct 2026
0164 systemd services: systemctl and journalctl basics systemd starts and supervises services on most Linux servers. systemctl starts, stops and enables them; journalctl shows their logs. Beginner · Concept · Linux Article Services & systemd 15 Oct 2026
0170 LVM explained: physical volumes, volume groups and logical volumes LVM puts a flexible layer between disks and filesystems, so you can grow volumes, add disks and take snapshots without repartitioning. Intermediate · Concept · Linux Article Disks, LVM & filesystems 15 Oct 2026
0177 Users, groups and sudo on Debian, Ubuntu and RHEL How Linux accounts and groups work, how to create users, and how sudo gives admin rights through the sudo group on Debian/Ubuntu… Beginner · Concept · Linux Article Users, sudo & hardening 15 Oct 2026
0181 Ansible concepts: inventory, modules, playbooks, idempotency and roles Ansible configures many servers over SSH from one control machine. Learn the core pieces: inventory, modules, tasks, playbooks, roles, and why runs… Beginner · Concept · Linux, macOS Article Ansible 15 Oct 2026
0187 Terraform concepts: providers, state, plan and apply, modules, and OpenTofu Terraform describes infrastructure in code, compares it with what exists, and changes only the difference. Learn providers, resources, state, the plan/apply loop,… Beginner · Concept · Any system Article Terraform 15 Oct 2026
0191 Prometheus concepts: pull model, exporters, node_exporter and PromQL basics Prometheus scrapes numeric metrics from your systems over HTTP and stores them as time series. Learn the pull model, metric types, node_exporter,… Intermediate · Concept · Linux Article Prometheus & Grafana 15 Oct 2026
0201 pg_hba.conf and PostgreSQL authentication methods pg_hba.conf decides who may connect from where and how they must prove who they are. Rules are checked top to bottom and… Intermediate · Concept · Linux Article Install & connect · Security & access 15 Oct 2026
0203 Physical backups and point-in-time recovery with pg_basebackup and WAL archiving A base backup plus a continuous archive of WAL files lets you restore a PostgreSQL cluster to any moment after the backup,… Advanced · Concept · Linux Article Backup & restore · Replication & high availability 15 Oct 2026
0204 VACUUM, autovacuum and table bloat in PostgreSQL Updates and deletes leave dead row versions behind. VACUUM makes that space reusable, keeps statistics fresh and prevents transaction ID wraparound; autovacuum… Intermediate · Concept · Linux Article Performance & tuning · Roles & administration 15 Oct 2026
0216 MySQL vs MariaDB: what actually differs MariaDB started as a fork of MySQL and still speaks the same client protocol, but GTIDs, JSON storage, authentication and tooling have… Intermediate · Concept · Linux Article Choosing a database · MySQL & MariaDB 15 Oct 2026
0217 MySQL binary logs and point-in-time recovery The binary log records every change after your last backup. Restore the backup, then replay the binary log up to just before… Advanced · Concept · Linux Article Backup & restore · Replication 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 · Concept · 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 · Concept · Any system Article Basics · Choosing a database 15 Oct 2026
0238 Redis persistence and high availability: RDB, AOF, replicas and Sentinel Redis keeps data in memory and writes it to disk with RDB snapshots, an append-only file, or both. Replicas copy data to… Intermediate · Concept · Linux Article Administration & persistence 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 · Concept · Any system Article Choosing a database · Database operations 15 Oct 2026