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Recently updated material, newest first.
06-10-2026
AI Agents
LLM-driven systems that plan, call tools, and act toward a goal.
APIs
Contracts that let separate software systems talk to each other.
Claude Code
Anthropic's agentic command-line coding tool.
Homebrew
The missing package manager for macOS and Linux.
Node.js
Server-side JavaScript runtime built on the V8 engine.
uv vs pip
How the uv toolchain compares to classic pip for Python package management.
06-09-2026
06-08-2026
AI Agents
LLM-driven systems that pursue a goal by interleaving reasoning, tool calls, and observations inside a loop — and that decide for themselves which step to take next.
az
Cross-platform command-line interface for managing Azure resources, running ARM-based and data-plane operations from a terminal or pipeline.
ccusage
Local-first CLI and TypeScript library that reads JSONL session logs from Claude Code, Codex, and 13 other coding agents to produce daily/weekly/monthly/session/billing-block reports of token spend.
Claude Code
Anthropic's agentic command-line coding assistant — a tool-using LLM that lives in your terminal, reads and edits your codebase, runs commands, and coordinates multi-step engineering work through natural language.
Cloud Computing
On-demand, network-accessible, metered access to a shared pool of configurable compute, storage, and platform services.
DevOps
A culture, set of practices, and toolchain that shortens the loop between writing software and running it in production.
JSON
Text-based data interchange format derived from JavaScript object literals and standardised as RFC 8259 / ECMA-404.
05-31-2026
@biomejs/biome
Package-level reference for @biomejs/biome on npm — install, single-binary toolchain replacing prettier+eslint, Node support, and alternatives.
@playwright/test
Package-level reference for @playwright/test and playwright on npm — install variants, browser-binary download, fixtures, traces, and alternatives.
@vue/cli
Reference for the legacy @vue/cli npm package — install, command surface, plugin model, and why create-vue + Vite is the recommended path for new projects.
ai
Package-level reference for the Vercel AI SDK — streamText, generateObject, tool calling, structured output, and the multi-provider model interface.
anyio
Package-level reference for anyio on PyPI — install, version policy, task groups, cancel scopes, and the API that runs identically on asyncio and trio.
astro
Package-level reference for the Astro framework on npm — install, integration ecosystem, runtime support, and SSR/SSG adapter gotchas.
attrs
Package-level reference for attrs on PyPI — install, @define vs @attr.s, validators, converters, and comparison with dataclasses.
autogen-agentchat
Package-level reference for the autogen-agentchat / autogen-core / autogen-ext family on PyPI plus the legacy pyautogen — install, rename history, versioning, and alternatives.
AWS CLI
Drive every AWS service from a terminal. Covers install (pip vs v2 installer), aws configure, profiles, SSO, day-to-day commands across S3 / EC2 / Lambda / IAM / STS, common scenarios, and credential precedence.
axios
Package-level reference for axios — interceptors, request configuration, error handling, and the migration story from 0.x to 1.x.
beautifulsoup4
Package-level reference for beautifulsoup4 on PyPI — install variants, parser-backend selection (lxml/html5lib/html.parser), and alternatives.
black
Package-level reference for black on PyPI — install variants, version policy, the [d] and [jupyter] extras, and how it relates to ruff format.
body-parser
Package-level reference for body-parser on npm — JSON, urlencoded, raw and text middleware, webhook signatures, and Express 4.16+ bundling.
boto3
Package-level reference for boto3 on PyPI — install, sessions, clients vs resources, paginators, version policy, and alternatives.
certifi
Package-level reference for certifi on PyPI — what the bundle contains, install, integration with requests / urllib3 / ssl, alternatives.
cffi
Package-level reference for cffi on PyPI — install, ABI vs API modes, build patterns, and integration with system libraries.
chalk
Package-level reference for the chalk ANSI-styling library on npm — install, ESM-only policy, peer-deps, and alternatives.
charset-normalizer
Package-level reference for charset-normalizer on PyPI — what it does, install, integration with requests, version policy, and alternatives.
chromadb
Package-level reference for chromadb on PyPI — install variants, server/client split, embedding-function extras, and alternative vector stores.
click
Package-level reference for the click CLI toolkit on PyPI — install, version policy, extras, and alternatives.
commander
Package-level reference for the commander CLI framework on npm — install, version policy, TypeScript extras, and alternatives.
concurrently
Package-level reference for concurrently on npm — install, output prefixing, kill-others, race-mode, and the npm-run-all2 comparison.
cors
Package-level reference for cors on npm — preflight handling, credentialed requests, dynamic origins, and Express integration.
crewai
Package-level reference for the crewai library on PyPI plus the crewai-tools companion — install, versioning, and multi-agent alternatives.
cryptography
Package-level reference for the cryptography library on PyPI — install, version policy, Fernet, asymmetric keys, X.509, and TLS contexts.
cypress
Package-level reference for cypress on npm — install size, binary caching, peer-dep landscape, playwright competition, and component-testing add-ons.
Cypress
Day-to-day Cypress CLI commands and config patterns — interactive runs, headless CI, intercepts, sessions, component testing, and Playwright comparison.
dagster
Package-level reference for Dagster on PyPI — install variants, the dagster-* plugin family, version policy, and alternatives.
dayjs
Package-level reference for the Day.js date library on npm — install, plugin model, version policy, and alternatives.
debug
Package-level reference for debug on npm — namespace pattern, DEBUG env enable, browser vs Node, and production wrapping.
diff2html-cli
Package-level reference for the diff2html-cli renderer on npm — install, runtime support, peer-deps, and alternatives.
django
Package-level reference for Django on PyPI — install variants, LTS release cadence, ecosystem companions, and alternatives.
dotenv
Package-level reference for the dotenv config loader on npm — install, native Node alternatives, dotenvx successor, and gotchas.
drizzle-orm
Package-level reference for Drizzle ORM — schema definitions, type-safe queries, relations, migrations with drizzle-kit, and deployment patterns.
dspy
Package-level reference for DSPy on PyPI — the dspy / dspy-ai rename, install variants, version policy, and alternatives.
duckdb
Package-level reference for duckdb — install, versioning, extensions, and gotchas. In-process columnar OLAP for Python.
effect
Package-level reference for the Effect library — Effect values, generators, fibers, error channels, dependency injection, and the 2.x → 3.x migration.
elysia
Package-level reference for Elysia — end-to-end type safety, plugins, Eden RPC client, schema validation, and Bun-first deployment.
esbuild
Package-level reference for esbuild on npm — bundle CLI, transform API, JS API, plugin system, and trade-offs vs Rollup, Webpack, and Vite.
esbuild
Daily-driver reference for esbuild — bundle CLI, transform API, JS API patterns, common build recipes.
eslint
Package-level reference for eslint on npm — install variants, flat config (v9) vs legacy .eslintrc, typescript-eslint, plugin ecosystem, and alternatives.
express
Package-level reference for Express on npm — install, middleware model, Node support, 4-to-5 migration, and production deployment.
fastapi
Package-level reference for FastAPI on PyPI — install variants, version policy, the `[all]` extra, ecosystem companions, and alternatives.
fastify
Package-level reference for the Fastify framework on npm — install, plugin model, Node support, and validation/encapsulation gotchas.
flask
Package-level reference for Flask on PyPI — install variants, version policy, extension ecosystem, and alternatives.
form-data
Package-level reference for form-data on npm — file uploads, streaming, headers, and the modern FormData web standard alternative.
fsspec
Package-level reference for fsspec on PyPI — install, protocols, chained URIs, caching layers, and integration with pandas / dask.
google-genai
Package-level reference for google-genai (the current Gemini SDK) and its predecessor google-generativeai — install, auth, versioning, and alternatives.
guidance
Package-level reference for the guidance library on PyPI — install, LLM-provider extras, versioning, and alternatives like instructor and outlines.
haystack-ai
Package-level reference for haystack-ai on PyPI — install variants, the farm-haystack v1 → haystack-ai v2 rename, integrations, and alternative frameworks.
helmet
Package-level reference for helmet on npm — default headers, CSP customization, per-route overrides, HSTS, and v7→v8 migration.
hono
Package-level reference for Hono — minimal routing, typed handlers, middleware, RPC client, and deployment to Cloudflare Workers, Bun, Deno, Node, and Vercel Edge.
http-server
Package-level reference for http-server on npm — install, HTTPS, gzip, proxy mode, basic auth, and the serve comparison.
httpx
Package-level reference for httpx on PyPI — install variants, version policy, extras, transport options, and alternatives.
idna
Package-level reference for idna on PyPI — IDNA2008 vs UTS46, encode/decode, install, integration with requests / urllib3, alternatives.
importlib-metadata
Package-level reference for importlib-metadata on PyPI — install, distribution lookups, entry points, and the stdlib relationship from Python 3.10+.
ioredis
Package-level reference for ioredis on npm — cluster, sentinel, pipelining, Lua scripts via defineCommand, and stability characteristics.
jest
Package-level reference for jest on npm — install variants, transformer ecosystem, peer-dep landscape, vitest competition, and migration paths.
Jest
Day-to-day Jest CLI commands and config patterns — running tests, mocks, snapshots, coverage, watch mode, and migration tips.
jinja2
Package-level reference for Jinja2 on PyPI — install, version policy, autoescape gotchas, sandboxing, and the template features behind Flask, Ansible, and Sphinx.
jupyter
Package-level reference for the jupyter meta-package on PyPI — install variants, what it pulls in, version policy, and alternatives.
langchain
Package-level reference for the langchain family on PyPI — install variants, partner packages, version churn, and alternatives.
langsmith
Package-level reference for the langsmith SDK on PyPI — install, versioning, env-var setup, and observability alternatives.
litestar
Package-level reference for Litestar on PyPI — install variants, version policy, the `[full]` extra, ecosystem companions, and alternatives.
lodash
Package-level reference for lodash on npm — modular imports, ES2020+ replacements, lodash/fp, debounce/throttle, and the honest 'you might not need this' framing.
loguru
Package-level reference for loguru on PyPI — install variants, version policy, and how it coexists with (does not replace) the stdlib logging module.
markupsafe
Package-level reference for markupsafe on PyPI — install, the Markup class, escape semantics, and its role as a Jinja2/Flask/Django dependency.
matplotlib
Package-level reference for matplotlib on PyPI — install variants, backends, version policy, extras, and alternatives.
modin
Package-level reference for modin — install, backend extras, versioning, and gotchas. Speeds up existing pandas code with a one-line import swap.
mongoose
Package-level reference for mongoose on npm — schemas, models, transactions, populate, indexes, and 7-to-8 migration.
mypy
Package-level reference for mypy on PyPI — install variants, Python compat, the types-* stub-package ecosystem, and alternatives.
mysql2
Package-level reference for mysql2 on npm — promise API, prepared statements, pooling, streaming, and migration from mysql.
ncu
The ncu CLI from npm-check-updates rewrites package.json to bump dependency versions — interactive mode, filters, doctor rollback, and workspaces support.
next
Package-level reference for Next.js — App Router, server components, server actions, middleware, caching, and the 14 → 15 → 16 migration path.
node-fetch
Package-level reference for node-fetch on npm — v2 (CJS) vs v3 (ESM), why Node 18+ built-in fetch obviates it, and migration paths.
nodemon
Package-level reference for nodemon on npm — watch globs, exec patterns, config files, and how it compares to node --watch and tsx watch.
nodemon
Daily-driver reference for nodemon — watch flags, exec patterns, config files, lifecycle events.
npm-check-updates
Package-level reference for npm-check-updates on npm — install, Node support, the ncu binary, doctor mode, workspaces, and where it fits next to npm outdated, taze, and bun update.
npm-run-all2
Package-level reference for npm-run-all2 on npm — install, glob-based script matching, run-s vs run-p, and migration from the unmaintained npm-run-all.
numpy
Package-level reference for numpy — install, versioning, ABI breaks, extras, and gotchas. The bedrock of the Python scientific stack.
openai
Package-level reference for openai on npm — Chat Completions, the Responses API, streaming, tool calls, structured outputs, embeddings, and the v4→v5 migration.
oxc-transform
Package-level reference for oxc-transform on npm — Rust transformer from the oxc toolchain, TS/JSX support, current API maturity, and place in the ecosystem.
packaging
Package-level reference for packaging on PyPI — Version, SpecifierSet, Requirement, markers, install, alternatives.
pandas
Package-level reference for pandas — install, versioning, Python compatibility, extras, and gotchas. The de-facto DataFrame library on PyPI.
pg
Package-level reference for node-postgres on npm — pools, parameterized queries, transactions, LISTEN/NOTIFY, and COPY streaming.
Pillow
Package-level reference for Pillow on PyPI — install variants, format-specific native deps, version policy, and alternatives.
pino
Package-level reference for pino on npm — child loggers, redaction, transports, serializers, and migration notes.
platformdirs
Package-level reference for platformdirs on PyPI — install, version policy, alternatives, and the per-OS path conventions it returns.
pluggy
Package-level reference for pluggy on PyPI — install, version policy, alternatives, and the hookspec/hookimpl model that powers pytest, tox, and devpi.
polars
Package-level reference for polars — install, versioning, extras, and gotchas. The Rust-powered Arrow-native alternative to pandas.
pre-commit
Package-level reference for pre-commit on PyPI — install variants, hook-pinning model, and how it composes with ruff, black, and mypy.
prefect
Package-level reference for Prefect on PyPI — install variants, version policy, cloud-vs-OSS extras, and alternatives.
prettier
Package-level reference for prettier on npm — install variants, v3 ESM-only switch, plugin model (Tailwind, Astro, etc.), Node support, and alternatives.
prisma
Package-level reference for prisma (CLI) and @prisma/client (runtime) on npm — install, generator, peer setup, Node and database support, and alternatives.
protobuf
Package-level reference for the protobuf package on PyPI — install, backend selection (upb / pure-Python / C++), .proto compilation, and gRPC integration.
pycparser
Package-level reference for pycparser on PyPI — install, AST walking, fake stdlib headers, and use as a cffi dependency.
pydantic
Package-level reference for Pydantic on PyPI — install variants, v1 vs v2 split, optional extras, and alternatives.
pygmentize
Highlight source code from the command line — many lexers, many output formats.
pygments
Package-level reference for Pygments on PyPI — install, version policy, lexers, formatters, and the pygmentize CLI it ships.
pytest
Package-level reference for pytest on PyPI — install variants, version policy, the pytest-* plugin ecosystem, and alternatives.
python-dateutil
Package-level reference for python-dateutil on PyPI — parser, relativedelta, rrule, timezone, install, alternatives.
PyYAML
Package-level reference for PyYAML on PyPI — safe_load vs load, dump, custom tags, install, alternatives like ruamel.yaml.
qdrant-client
Package-level reference for qdrant-client on PyPI — install variants, server version matching, gRPC vs HTTP, fastembed extras, and alternatives.
qs
Package-level reference for qs on npm — nested objects, arrays, allowDots, prototype-pollution history, and URLSearchParams comparison.
ragas
Package-level reference for ragas on PyPI — install variants, LLM-as-judge dependencies, metric churn, and alternative evaluators.
react
Package-level reference for the React library on npm — install, paired react-dom, server-component model, and upgrade gotchas.
react-dom
Package-level reference for react-dom — client/server rendering, hydration, portals, flushSync, and the React 19 root API.
redis
Package-level reference for node-redis on npm — pipelining, pub/sub, TTL, the v3-to-v4 API rewrite, and rate-limit patterns.
reflex
Package-level reference for reflex on PyPI — install variants, Node.js requirement, version policy, and alternatives.
requests
Package-level reference for the requests HTTP client on PyPI — install variants, version policy, extras, and alternatives.
rich
Package-level reference for rich on PyPI — install variants, single-file design, version policy, and alternatives.
rimraf
Package-level reference for rimraf on npm — install, API, why it still exists in the Node fs.rm era, and migration paths.
rolldown
Package-level reference for rolldown on npm — Rust rewrite of Rollup, API compatibility goals, current limitations, and the Vite migration path.
rollup
Package-level reference for rollup on npm — library bundling, multi-format output, plugin ecosystem, tree shaking, and the Rolldown migration.
rollup
Daily-driver reference for rollup — CLI commands, multi-format output, plugin chain patterns, library publishing config.
ruff
Package-level reference for ruff on PyPI — install variants, fast-moving version policy, and how a single binary subsumes flake8, isort, pyupgrade, and black.
scikit-learn
Package-level reference for scikit-learn — install, versioning, extras, and gotchas. The de-facto classical-ML library on PyPI.
scipy
Package-level reference for scipy — install, versioning, submodules, license caveats, and gotchas. Optimization, statistics, signal processing, and linear algebra.
semantic-kernel
Package-level reference for semantic-kernel on PyPI — install variants, the Python vs .NET split, provider extras, and alternative frameworks.
sentence-transformers
Package-level reference for the sentence-transformers library on PyPI — install, transformers/torch deps, model registry, and embedding alternatives.
serve
Package-level reference for serve on npm — install, SPA fallback, auth, CORS, and when to reach for caddy or python -m http.server instead.
six
Package-level reference for six on PyPI — what it did, why it still appears in dependency trees, and why new code should avoid it.
SQLAlchemy
Package-level reference for SQLAlchemy on PyPI — install variants, dialect drivers, version policy, extras, and alternatives.
sqlmodel
Package-level reference for SQLModel on PyPI — install, version policy, dependencies, and alternatives.
streamlit
Package-level reference for the streamlit framework on PyPI — install variants, version policy, extras, and alternatives.
tqdm
Package-level reference for tqdm on PyPI — install variants, notebook extra, version policy, and alternatives.
transformers
Package-level reference for the Hugging Face transformers library on PyPI — install extras, backend choice, versioning, and alternatives.
trulens-eval
Package-level reference for trulens-eval on PyPI — install variants, the trulens umbrella rename, framework extras, and alternative evaluators.
ts-node
Package-level reference for ts-node on npm — TypeScript-aware REPL, transpile-only mode, ESM loader, and its tsx-driven decline.
ts-node
Daily-driver reference for the ts-node CLI — REPL, transpile-only mode, ESM loader, common script patterns.
tsx
Package-level reference for tsx on npm — enhanced Node.js runtime for TypeScript and ESM, watch mode, ts-node replacement, and Node loader integration.
tsx
Daily-driver reference for the tsx CLI — run TS files, watch mode, ESM/CJS handling, Node loader integration.
turbo
Package-level reference for turbo on npm — install, pipelines, remote cache, filter syntax, and the Nx / pnpm-workspaces comparison.
Turborepo (turbo)
Day-to-day Turborepo CLI commands and turbo.json config patterns — pipelines, filters, remote cache, prune, and CI integration.
type-fest
Package-level reference for type-fest on npm — install (dev-only, pure types), TS version requirements, recursion limits, and alternatives.
typer
Package-level reference for the Typer CLI library on PyPI — install variants, version policy, extras, and alternatives.
typing-extensions
Package-level reference for typing-extensions on PyPI — what's backported, install, version policy, and migration to stdlib.
unstructured
Package-level reference for unstructured on PyPI — install variants, the huge extras tree, system-level dependencies, and alternative parsers.
urllib3
Package-level reference for urllib3 on PyPI — connection pooling, retries, TLS, version policy, and alternatives.
uuid
Package-level reference for uuid on npm — v4 random, v5 namespace, v7 sortable, ESM-only since v9, and namespace pattern.
valibot
Package-level reference for valibot — schemas, transforms, pipes, branding, safeParse, and the tree-shaking advantage over zod.
vercel
Package-level reference for the vercel CLI on npm — install, Node support, command surface, project linking model, and where it fits next to wrangler / netlify-cli.
vercel
Vercel's official CLI for deploying frontend apps, managing environments, syncing env vars, tailing logs, and rolling back via alias re-pointing.
vite
Package-level reference for vite on npm — install variants, scaffold templates, plugin ecosystem under @vitejs/plugin-*, framework integrations, and alternatives.
vitest
Package-level reference for vitest on npm — install variants, vite peer-dep, UI and coverage add-ons, environments, and alternatives.
vue
Package-level reference for Vue 3 — Composition API, reactivity, single-file components, the Vue 2 → 3 migration, and the broader ecosystem (Pinia, Vue Router, Nuxt).
vue (@vue/cli)
The legacy @vue/cli command-line tool for scaffolding and serving Vue projects — deprecated in favour of create-vue + Vite, retained as reference for existing apps.
weaviate-client
Package-level reference for weaviate-client on PyPI — install variants, the v3 → v4 API split, gRPC, and alternative vector stores.
webpack
Package-level reference for webpack on npm — loaders, plugins, code splitting, asset modules, module federation, and the slow migration toward Rspack and Vite.
webpack
Daily-driver reference for webpack — CLI commands, dev server, loaders, plugins, code splitting, common config recipes.
winston
Package-level reference for winston on npm — transports, formats, levels, daily rotation, and production patterns.
wrangler
Package-level reference for the wrangler CLI on npm — install, Node support, transitive dependency footprint, and platform-binding gotchas.
ws
Package-level reference for ws on npm — client/server, broadcast, heartbeat, compression, and security pitfalls.
yargs
Package-level reference for yargs on npm — command builders, middleware, prototype-pollution history, and alternatives like commander.
zod
Package-level reference for zod on npm — install variants, v4 breaking changes (looseObject, mini build), companion packages, and alternatives.
05-26-2026
arp
Display, add, and delete entries in the Windows ARP (Address Resolution Protocol) cache — map IP addresses to MAC addresses, detect IP conflicts, and diagnose Layer 2 connectivity issues.
attrib
View and modify Windows file attributes (hidden, read-only, system, archive) from the command line. Covers all attribute flags, recursive operations, and practical recipes for unhiding malware-hidden files and managing backups.
bcdedit
View and modify the Windows Boot Configuration Data store — manage boot entries, set default OS, change timeouts, enable debugging, and configure boot options from an elevated command prompt.
beets Music Organizer
Importing, tagging, querying, and organizing a music library with beets — config, plugins, queries, and common workflows on Windows.
caffeinate
Prevent display, idle, system, or user-active sleep for the duration of a command, a fixed time, or a process — without permanently changing pmset.
cd
Navigate the Windows command prompt's current working directory. Covers drive switching, absolute and relative paths, UNC paths, and path-with-spaces quoting.
certutil
The dual-purpose Windows CLI for certificate-store management and as the most reliable built-in tool for file hashing, base64 encoding, and CRL/CTL handling — no install required.
chkdsk
Scan a FAT or NTFS volume for file system errors and bad sectors, optionally repairing them — the built-in Windows disk health and integrity tool for drives and volumes.
Chocolatey
Install, upgrade, pin, and script software installs on Windows with the choco CLI, packages.config files, and custom sources.
CICS CEMT
Drive the CICS Master Terminal transaction — INQUIRE, SET, and PERFORM verbs for programs, tasks, files, connections, and region-level operations like NEWCOPY refresh and SNAP dumps.
cls
Clear all text from the cmd.exe or PowerShell console window and reset the cursor to the top-left — the single command for resetting a terminal session's visible output.
codesign
End-to-end macOS distribution pipeline — sign binaries and app bundles with codesign, notarize with notarytool, staple tickets with stapler, and verify Gatekeeper acceptance with spctl.
copy
Copy one or more files to a new location in the Windows command prompt. Covers single-file copy, wildcard batches, file concatenation, and binary vs ASCII modes.
Db2 SPUFI
Run SQL through SPUFI, drive Db2 with DSN subsystem commands, BIND packages and plans, schedule DSNTEP2 in JCL, query the SYSIBM catalog, and generate DCLGEN.
defaults
Read, write, search, and delete macOS preference plists with the `defaults` CLI: data types, domains, current-host scope, the killall dance, finding undocumented keys via plist diffing, and a curated bootstrap recipe.
defrag
Analyze, defragment, and optimize volumes from the command line — consolidate free space on HDDs, issue TRIM on SSDs, and schedule or review optimization tasks.
del
Delete one or more files from the Windows command prompt. Covers wildcards, quiet mode, attribute overrides, recursive deletion patterns, and the distinction from rmdir.
DFSMShsm
Migrate, recall, back up, and recover datasets across ML0/ML1/ML2 tiers with TSO H-commands and ARC operator commands; bulk-recall recipes, recall timing, and audit messages.
DFSORT
IBM DFSORT control statements and ICETOOL operators for sorting, merging, joining, and reshaping batch datasets on z/OS.
dir
Display files and folders in a directory with filtering, sorting, formatting, and recursive traversal options. The Windows cmd.exe equivalent of Unix ls.
diskpart
Create, delete, format, extend, shrink, and assign drive letters to disk partitions from the Windows command prompt using an interactive or scripted REPL interface.
diskutil
Command-line front-end to Disk Utility on macOS — list, partition, format, repair, encrypt, and snapshot APFS containers, plus build and tear down software RAID volumes.
dism
Service Windows images and the running OS — enable/disable optional features, repair the component store, mount and edit WIM/ESD images, add drivers, and manage editions from an elevated command prompt.
driverquery
Display all installed device drivers on a local or remote Windows machine — module name, type, link date, and driver file path — for hardware audits and troubleshooting.
duti
Drive macOS Launch Services from the command line — assign default apps for UTIs, file extensions, and URL schemes; understand the viewer/editor/all/shell/none roles; bulk-load file associations from a settings file; rebuild the Launch Services database when changes refuse to stick.
echo
Print text to stdout, expand environment variables, write blank lines, redirect output to files, and toggle command-echoing in cmd.exe batch scripts.
fc
Compare two text or binary files line-by-line or byte-by-byte and report their differences — the built-in Windows equivalent of Unix diff for quick file audits in cmd.exe.
findstr
Search for string patterns inside files or piped input on Windows — the built-in grep equivalent for cmd.exe, with support for regular expressions, case-insensitive matching, and recursive directory searches.
fsutil
Inspect and manage NTFS file system internals — query volume info, manage hard links, sparse files, reparse points, the USN journal, and the dirty bit — from an elevated command prompt.
GDG
Define, reference, and clean up z/OS generation data groups via IDCAMS — relative generations, rollover behaviour, model DSCBs, and the modern GDGEXTENDED mode.
getmac
Display the MAC (hardware) addresses and associated transport names for all network adapters on a local or remote Windows machine — useful for asset inventory, DHCP reservation setup, and network access control.
gpresult & gpupdate
Inspect the Resultant Set of Policy that applied to a user and computer with gpresult, then force a refresh with gpupdate — including HTML reports, scope filtering, and the classic 'why didn't my GPO take effect?' workflow.
Homebrew
Install, search, upgrade, pin, tap, bottle, and bundle packages with Homebrew on macOS: formulae vs casks, brew services, Brewfile-driven machine bootstrap, Apple-Silicon vs Intel prefixes, brew doctor, brew cleanup, and recovery recipes.
hostname
Display the DNS hostname of the local Windows machine from the command prompt — useful in scripts to identify the machine without parsing systeminfo output.
icacls
Display and modify NTFS access control lists on files and directories — grant, deny, or remove permissions for users and groups, manage inheritance, and save or restore full ACL sets.
IDCAMS
Define, copy, list, alter, and delete VSAM clusters and general datasets — the everyday utility for catalog and dataset lifecycle on z/OS.
IEBCOPY
IBM utility for copying, merging, compressing, unloading, and reloading PDS and PDSE libraries on z/OS, including member selection, rename, and exclusion.
ipconfig
Display and manage TCP/IP network configuration for all adapters on a Windows machine — covers full adapter details, DNS cache operations, and DHCP lease management.
ISPF Edit
Deep dive into the ISPF editor — primary commands, line commands, BNDS/CC/MM column edits, ISREDIT macro services, profile management, and recovery.
JCL DD Statement
Comprehensive reference for the JCL DD statement: DSN, DISP, DCB, SPACE, UNIT, VOL=SER, concatenation, DUMMY, SYSOUT, KEYLEN.
JCL Quick Reference
Job Control Language syntax, common statements, EXEC, DD, and SYSOUT patterns.
JES2
z/OS Job Entry Subsystem 2 operator slash-commands for jobs, initiators, output, classes, NJE, and spool — from the console and from SDSF.
launchctl
Bootstrap, bootout, kickstart, print, and enable/disable services with launchctl on macOS: agents vs daemons, plist anatomy, user/system domains, RunAtLoad vs KeepAlive vs StartInterval vs StartCalendarInterval, and recipes for periodic scripts and on-demand workers.
logman
Create, start, stop, and manage Data Collector Sets for performance counters, event traces, and configuration data — the command-line interface to Windows Performance Monitor for scripted monitoring and automated log collection.
macOS CLI
Comprehensive macOS terminal reference covering file management, processes, networking, Homebrew, defaults, diskutil, launchctl, pbcopy/pbpaste, open, say, and power-user recipes.
mdfind
Query macOS's Spotlight index from the shell — fast name, content, and metadata search across the whole filesystem, with scope, attributes, and live-update modes.
mkdir / md
Create one or more directories from the Windows command prompt. Covers single and nested directory creation, batch patterns, and common scripting idioms.
mountvol
List, create, and remove NTFS volume mount points and display the unique volume GUID path for any drive letter or directory junction from the command prompt.
move
Move files to a new location or rename them within the Windows command prompt. Covers single files, wildcards, directory renames, overwrite control, and cross-drive behaviour.
nano
GNU's small, on-screen-hinted terminal text editor — the default modal-free alternative to vi/emacs that you can drive without ever learning a command vocabulary.
net localgroup
Create, delete, and modify local security groups on a Windows machine — add or remove members, list group memberships, and manage built-in groups from the command prompt.
net user
Create, modify, delete, and list local Windows user accounts from the command prompt — set passwords, manage account expiry, lock/unlock accounts, and control logon hours.
netsh
Configure network interfaces, firewall rules, wireless profiles, port proxies, and Winsock settings from an elevated command prompt — the comprehensive Windows network configuration CLI.
netstat
Display active TCP/UDP connections, listening ports, routing tables, interface statistics, and per-connection process IDs from the Windows command prompt.
networksetup
Script every aspect of macOS network configuration — Wi-Fi joining, DNS servers, proxies, locations, and service order — from a single first-party command-line tool.
nslookup
Query DNS servers for A, AAAA, MX, TXT, NS, PTR, and other resource records from the Windows command prompt — the built-in tool for diagnosing name resolution issues.
osascript
Drive macOS GUI apps, system events, dialogs, notifications, and Finder from the terminal using AppleScript or JavaScript for Automation (JXA).
pathping
Trace the route to a destination and measure per-hop packet loss and latency over a sustained sampling period — more diagnostic than tracert and more thorough than ping for identifying intermittent network problems.
pbcopy & pbpaste
Pipe data into and out of the macOS pasteboard from the shell — multi-pasteboard targets, newline handling, shell aliases, and real-world copy-paste recipes.
ping
Send ICMP echo requests to a host to test reachability, measure round-trip latency, and detect packet loss from the Windows command prompt.
pmset
Inspect and configure sleep, wake, hibernate, and battery behaviour on macOS. Covers per-source profiles, scheduled wake, sleep-prevention diagnostics, battery reports, and hibernate modes.
powercfg
Manage Windows power plans, enable or disable hibernation, diagnose battery health and sleep failures, and generate energy efficiency reports from the command prompt.
PowerShell Built-in Variables
Complete reference for every automatic and preference variable built into PowerShell — $_, $Error, $MyInvocation, $PSCmdlet, $Host, $PSVersionTable, $ExecutionContext, and all preference variables that tune runtime behaviour.
PowerShell Error Handling
Master terminating vs non-terminating errors, $ErrorActionPreference, try/catch/finally, throw vs Write-Error, transcripts, and strict mode.
PowerShell Essentials
Variables, operators, pipelines, Where-Object, ForEach-Object, Select-Object, sorting, grouping, remoting, jobs, CIM, registry, JSON, error handling, and common cmdlets.
PowerShell Modules
Install, discover, update, and author PowerShell modules: PowerShellGet, PSResourceGet, the Gallery, $PSModulePath, $PROFILE customisation, PSReadLine, SecretManagement, and the must-have module shortlist.
PowerShell Pipelines
Deep dive on PowerShell's object pipeline: Where-Object, Select-Object, ForEach-Object, Sort-Object, Group-Object, Measure-Object, Compare-Object, Out-GridView, parallel execution, and the two filter forms.
PowerShell Remoting
Execute PowerShell against one or many remote hosts using WinRM or SSH transport, persistent sessions, credential management, and JEA.
PowerShell Scripting
Author production-grade PowerShell: advanced functions with [CmdletBinding()], parameter validation, pipeline-bound parameters, splatting, switch parameters, .ps1 vs .psm1, and all the control-flow constructs.
RACF
TSO commands for RACF user, group, dataset, and general-resource profile administration on z/OS.
reg
Query, add, modify, export, and import Windows registry keys and values with the built-in reg.exe — the scriptable, no-dependency tool for everything from one-off tweaks to full backup-and-restore.
REXX Snippets
Practical REXX patterns for z/OS automation, TSO commands, and ISPF services.
rmdir / rd
Delete empty or entire directory trees from the Windows command prompt. Covers the /S and /Q flags, force-removing read-only trees, and safe deletion patterns.
robocopy
Production-grade file and directory synchronisation with mirroring, multi-threading, retry logic, logging, and exclusion filters. The go-to for backup scripts and deployment pipelines on Windows.
route
Display, add, delete, and modify entries in the Windows IP routing table — control how packets are forwarded between subnets, add persistent static routes, and diagnose routing failures.
runas
Launch a program in the security context of a different user account — elevate to Administrator, switch to a service account, or test application behaviour under a restricted identity.
sc
Query, create, configure, start, stop, and delete Windows services from the command line — the scripting interface to the Service Control Manager, equivalent to the Services MMC snap-in but fully automatable.
schtasks
Create, query, run, end, and delete scheduled tasks on local or remote Windows machines from the command prompt — the scripting interface to Windows Task Scheduler.
Scoop
Install dev tools without admin rights using Scoop — buckets, manifests, multi-version installs, and reproducible setups.
SDSF
Browse, filter, and act on JES2 spool from inside ISPF — find your job, read SYSOUT, cancel, purge, and issue operator commands.
set
Set, display, and delete cmd.exe environment variables within the current session, perform integer arithmetic with /A, and read interactive user input with /P.
shutdown
Initiate, schedule, abort, or force a shutdown, restart, logoff, hibernate, or sleep on a local or remote Windows machine from the command line — essential for scripted maintenance, patch automation, and remote administration.
sips
macOS built-in image processor covering format conversion, resizing, cropping, rotation, color profiles, metadata inspection, and batch processing recipes.
softwareupdate
Deep-dive on softwareupdate(8), Apple's CLI for macOS system updates — listing pending updates, installing recommended-only or specific items, scheduling, ignoring updates, installing Rosetta and Command Line Tools, and pairing with mas and brew for full system update automation.
ssh
Connect to remote hosts, transfer files, and forward ports over an encrypted channel using the OpenSSH client built into Windows 10 and later.
Sysinternals
Bootstrap and drive the headless Sysinternals utilities — PsExec, Handle, PsList, Autoruns, ProcMon, ListDLLs — for process spelunking, file-lock hunting, autostart auditing and scripted system tracing on Windows.
system_profiler
Deep-dive on system_profiler(8) — macOS's built-in inventory tool. Covers data types, text/XML/JSON output, piping into jq and plutil, common SP* probes (hardware, displays, memory, storage, USB, network, software), detail levels, and fleet inventory recipes.
systeminfo
Display detailed OS, hardware, and network configuration for the local or a remote Windows machine. Covers output formats, remote querying, filtering, and parsing in scripts.
takeown
Transfer ownership of files and directories to the current user or the Administrators group from an elevated command prompt — a prerequisite for modifying ACLs on system-protected paths.
taskkill
End one or more running Windows processes by PID or image name from the command prompt, with options for force termination, process tree killing, filtering, and remote targets.
tasklist
Display all running processes on a local or remote Windows machine with PID, memory usage, session, and optional service or module details — the cmd.exe equivalent of Task Manager for scripts.
timeout
Pause a batch script for a specified number of seconds with an optional keypress bypass — a reliable replacement for the ping-delay idiom and a safer alternative to sleep in Windows CMD scripts.
tmutil
Drive Time Machine backups, destinations, exclusions, local APFS snapshots, restores, and verification entirely from the terminal — without opening System Settings.
tracert
Trace the sequence of routers between your machine and a destination by sending probes with increasing TTL values — the go-to tool for locating where a network path breaks or introduces high latency.
TSO/ISPF Navigation
Complete ISPF menu options, primary commands, line commands, edit profile, utilities, DSLIST, SDSF, TSO commands, RACF, and keyboard shortcuts.
tzutil & w32tm
Read and set the system timezone with tzutil, then query, configure, and force-sync the Windows Time service with w32tm — including NTP peer configuration and Kerberos-clock-drift recovery.
USS
The UNIX side of z/OS — OMVS, ISHELL, oedit, BPXBATCH, file tagging, zFS, and bridging shell scripts to MVS batch.
wevtutil
Query, export, clear, and manage Windows Event Log channels from the command line — the primary CLI for event log automation, log archiving, and scripted log analysis on Windows.
whoami
Display the current user name, SID, group memberships, and privileges from the Windows command prompt — essential for auditing security context in scripts and support scenarios.
Windows Terminal
Configure Windows Terminal — settings.json structure, profiles for pwsh/cmd/wsl/ssh, keybindings, colour schemes, panes, and the wt.exe CLI.
winget Package Manager
Installing, upgrading, and managing packages with Windows Package Manager.
wmic
Query and manage Windows system information — hardware, software, processes, services, and more — from the command prompt using WMI classes and WMIC's SQL-like syntax.
wsl
Install, list, export, import, configure, and clone WSL distributions using the wsl.exe command on Windows 10 and 11.
WSL Interoperability
Running Linux tools from Windows and vice versa, file system access, and networking between WSL and Windows.
xattr
Deep-dive on macOS extended attributes — listing, reading, writing, and removing xattrs with xattr(1); the Gatekeeper com.apple.quarantine flag; Spotlight metadata attributes; ACLs via ls -le and chmod +a; preserving attributes on copy with cp -p and rsync -X.
xcopy
Copy files and directory trees with attribute preservation, date filtering, exclusion lists, and verification. The step between copy and robocopy for most scripting needs.
yt-dlp
Downloading video and audio from YouTube and hundreds of other sites with yt-dlp — formats, playlists, subtitles, post-processing, and config.
z/OS FTP Reference
FTP from TSO, batch FTP via JCL, SITE parameters, transfer modes, FTPS, FTP.DATA configuration, and JES spool transfers.
z/OS TCP/IP
Drive the z/OS Communications Server TCP/IP stack — NETSTAT variants, PING, TRACERTE, RESOLVE, PROFILE.TCPIP configuration, OMPROUTE, and SSH from z/OS UNIX, with end-to-end troubleshooting recipes.
Zowe CLI
Open-source command-line bridge into z/OS — manage datasets, jobs, USS files, consoles, TSO, and Db2 from Mac/Linux/Windows over z/OSMF or RSE-API.
05-25-2026
.d.ts Files
Authoring .d.ts files — ambient declarations, declare module 'foo', asset typing (*.svg?raw), declare global, triple-slash refs, and the home-hero.svg?raw pattern used in this project.
Agent Frameworks Comparison
Side-by-side comparison of LangChain, LlamaIndex, AutoGen, CrewAI, Haystack, and Semantic Kernel for building LLM-powered applications and agent systems. Covers strengths, weaknesses, and when to pick each.
APIs
A versioned contract between two pieces of software — endpoints, verbs, payload shapes, errors, and auth — that decouples a caller from an implementation.
Approvals & Sandboxing
Control what Codex CLI can do — approval policies (untrusted, on-request, never), sandbox modes (read-only, workspace-write, danger-full-access), OS-native sandbox mechanics, and --full-auto.
apt-get Package Management
Debian and Ubuntu package management — update, install, remove, upgrade, and maintain packages with apt-get.
argparse
Parse command-line arguments with Python's stdlib argparse module. Covers positional/optional args, subparsers, nargs, validation, mutually exclusive groups, FileType, env-var fallbacks, and argcomplete.
aria2c Download Utility
Fast, multi-protocol download utility supporting HTTP(S), FTP, SFTP, BitTorrent, and Metalink with resumption and parallel connections.
Astro
Astro is a multi-page, content-first web framework with an islands architecture — server-render Markdown, MDX, and component pages to static HTML, then hydrate interactive widgets selectively with React, Vue, Svelte, or Solid.
Asynchronous Programming
Non-blocking concurrency built on event loops, futures, promises, and coroutines that lets a single thread overlap many in-flight I/O operations.
awk / gawk
Pattern-action language for structured text. Field splitting, built-in variables, arithmetic, string functions, arrays, BEGIN/END blocks, and practical data-processing recipes.
Bash
Comprehensive Bash scripting reference covering variables, parameter expansion, control flow, functions, arrays, string manipulation, arithmetic, traps, process substitution, and the Bash 5.3 in-shell command substitution forms.
bat
A cat clone with syntax highlighting, Git integration, line numbers, paging, and diff support. Drop-in replacement with many quality-of-life improvements for viewing files in the terminal.
BeautifulSoup
Parse, search, and mutate HTML/XML with BeautifulSoup 4. Covers parser choice (html.parser/lxml/html5lib), find/find_all/select, tree navigation, attribute access, and pairing with requests/httpx/playwright for end-to-end scraping.
Big-O
A practical Big-O reference — common data structures, algorithms, amortized analysis, space vs time, and language-specific gotchas for Python, JavaScript, and TypeScript.
Biome
Rust-based all-in-one linter and formatter for JS/TS/JSON/CSS/GraphQL. Single binary, single config, 10-100x faster than ESLint+Prettier.
Branded Types
Branded (a.k.a. nominal, opaque, tagged) types add a phantom marker to a primitive so the compiler refuses to mix two strings — useful for IDs, units, validated input, and money. Covers hand-rolled brands, type-fest's Opaque/Tagged, Zod's .brand(), class-based brands, and runtime validation pairings.
Bun
Bun is a fast all-in-one JavaScript runtime, package manager, bundler, and test runner written in Zig — a drop-in replacement for Node.js and npm with built-in TypeScript and JSX support.
Cargo Crates
Cheat sheets for Rust crates from crates.io — async runtimes, serialization, CLI builders, HTTP clients, and more.
Chain-of-Thought Prompting
CoT prompting techniques — zero-shot CoT, few-shot CoT, self-consistency, tree of thoughts, and how reasoning models compare with prompted reasoning.
Chalk
Apply ANSI colours, backgrounds, and text styles to terminal output in Node.js using Chalk's chainable API, plus comparisons with picocolors and patterns for building polished CLI UX.
Claude API
The Anthropic Message Batches API — create, poll, retrieve, and stream results at 50% off list price for asynchronous bulk processing of thousands of Claude requests.
Claude API
The Anthropic Files API — upload PDFs, images, and text once and reference them by `file_id` across multiple messages, with citations, lifecycle management, and Workbench integration.
Claude API
The Anthropic Claude API — Python and TypeScript SDKs, streaming, tool use, batches, prompt caching, files, vision, and agentic loops.
Claude API
Anthropic prompt caching — `cache_control`, 5-minute TTL, 1-hour beta, cache breakpoints, cost math, multi-turn caching patterns, and recipes for system prompts, tools, and documents.
Claude API
Complete Python SDK reference for the Anthropic Claude API — messages, streaming, vision, extended thinking, prompt caching, batch processing, and token counting.
Claude API
Streaming responses from the Anthropic API — server-sent events, event types, async iteration in Python and TypeScript, partial tool input, error handling, and retry strategies.
Claude API
Complete TypeScript SDK reference for the Anthropic Claude API — install, messages.create, streaming, tool use, vision, types, and Node/Deno/Bun integration.
Claude Code
Anthropic's agentic CLI — installation, configuration, slash commands, hooks, MCP integration, subagents, skills, statusline, and power-user workflows.
Claude Code CLI
All claude CLI flags, startup modes, non-interactive usage, environment variables, keyboard shortcuts, subcommands, exit codes, and configuration file locations in one place.
Claude Code Hooks
Automate Claude Code lifecycle events with shell hooks — PreToolUse, PostToolUse, UserPromptSubmit, Notification, Stop, SubagentStop, and PreCompact. Covers configuration, environment variables, JSON I/O, exit codes, and blocking examples.
Claude Code MCP Servers
Add, configure, and build Model Context Protocol (MCP) servers for Claude Code — HTTP, SSE, and stdio transports, management commands, permission rules, and a curated list of useful servers.
Claude Code Overview
Install, configure, and use Claude Code — Anthropic's agentic CLI. Covers interactive mode, headless scripting, CLAUDE.md memory files, the project/user settings hierarchy, IDE integration, and authentication.
Claude Code Power-User Tips
Advanced Claude Code workflows — effective CLAUDE.md authoring, custom skills, multi-agent patterns, headless scripting, cost control, keyboard shortcuts, prompt caching, and daily workflow techniques.
Claude Code Settings and Permissions
Complete settings.json schema for Claude Code — permission rules, tool allowlists/denylists, environment variables, hooks, MCP, statusline, model selection, and file precedence.
Claude Code Skills
Author and load custom Claude Code skills — how skills are discovered, the SKILL.md schema, available-skills list, packaging, project-vs-user scope, plugin namespacing, and the difference from slash commands.
Claude Code Slash Commands
Complete reference for every built-in Claude Code slash command — session control, context management, configuration, tools, MCP, and authoring custom commands with arguments.
Claude Code Statusline
Customise the Claude Code statusline — settings.json keys, the JSON context passed to scripts, available variables (model, session id, cwd, branch, cost), and example scripts in bash, python, and Node.
Claude Code Subagents
Spawn isolated subagents with the Task tool — Plan, Explore, general-purpose, project-defined agents, isolation modes including worktrees, background runs, and orchestration patterns.
Claude Tool Use (Function Calling)
Define tools, handle tool calls, run agentic loops, use parallel tools, and manage errors with the Claude API.
Code Review
A practical guide to reviewing and authoring pull requests — small PRs, naming, control flow, error paths, security, performance, and GitHub PR conventions.
Codex CLI Overview
Install and use OpenAI's Codex CLI — the open-source agentic coding tool. Covers authentication, interactive mode, headless exec, ~/.codex/ layout, and AGENTS.md project memory.
Codex Configuration
Complete config.toml reference for Codex CLI — model selection, approval policies, sandbox modes, profiles, MCP server stubs, shell environment, notify hooks, and project trust levels.
codex exec
Complete reference for codex exec — scripted invocation, stdin piping, JSON event streams, output formats, exit codes, timeouts, and automation patterns for CI, git hooks, and shell pipelines.
Codex MCP Servers
Add and configure Model Context Protocol (MCP) servers in Codex CLI — config.toml [mcp_servers.*] reference, the codex mcp subcommand, per-server tool approval modes, and the /mcp runtime command.
Codex Slash Commands
Complete reference for every built-in Codex CLI slash command — session control, model switching, sandboxing, MCP management, and TUI utilities.
Codex Sub-Agents & Task Delegation
How Codex CLI supports delegating to child agents — the experimental /agent system, codex exec as a sub-agent pattern, MCP-mediated agent-to-agent calls, isolation boundaries, and orchestration patterns.
Codex Tips & AGENTS.md
Advanced Codex CLI workflows — AGENTS.md authoring, profiles, experimental hooks, notify callbacks, non-interactive exec scripting, session resume and fork, and codex cloud.
Commander.js
Build full-featured Node.js CLIs with positional arguments, typed options, subcommands, auto-generated help, lifecycle hooks, and a distributable bin in package.json.
cron
Time-based job scheduler on Unix. Covers crontab syntax, user vs. system crontabs, environment quirks, logging, anacron, and the modern systemd timer alternative.
curl
Transfer data with URLs. Covers HTTP methods, headers, authentication, forms, TLS, cookies, proxies, timeouts, parallel downloads, and a comprehensive recipe collection.
cut, paste & join
Extract columns by delimiter or byte position (cut), merge files column-wise (paste), and join on a common key field (join). Essential for tab/CSV/field-delimited data.
dataclasses
Define typed data containers with @dataclass — frozen, slots, kw_only, default_factory, __post_init__, asdict, replace, and how it compares to attrs, pydantic, NamedTuple, TypedDict.
datetime
Work with dates, times, and timezones in Python using the stdlib datetime module and zoneinfo. Covers aware vs naive datetimes, ISO-8601 parsing, strftime/strptime, timedelta arithmetic, and DST handling.
Day.js
Parse, format, manipulate, compare, and convert timezones for dates in JavaScript using Day.js — a 2 kB Moment-compatible alternative with a plugin-based architecture.
Declaration Merging
Deep dive into TypeScript declaration merging — interface merging, namespace + class, namespace + function, module augmentation, global augmentation, and the Express Request pattern.
Deno
Deno is a secure, modern JavaScript and TypeScript runtime built on V8 with permission-based sandboxing, built-in TypeScript, a curated standard library on JSR, and a complete toolchain (fmt, lint, test, bench, compile).
Design Patterns
A practical reference for classic OOP design patterns — Strategy, Observer, Factory, Adapter, Decorator, Repository — with examples in Python, TypeScript, and Go.
df, du & duf
Check filesystem free space (df), measure directory sizes (du), and view a colourful disk overview (duf). Covers all key flags, human-readable output, modern alternatives (dust, gdu, ncdu), and common sysadmin recipes.
dig
Query DNS records of any type from any resolver — A, AAAA, MX, TXT, NS, SOA, SRV, CAA — with formatted output, reverse lookups, and full delegation tracing.
Discriminated Unions
Discriminated unions model finite states with a shared literal tag, enabling exhaustive narrowing in switch statements, Result-style error handling, reducer actions, and pattern-matched API responses.
DNS
The hierarchical, cached, globally-distributed naming system that turns human-readable hostnames into IP addresses, mail routes, service endpoints, and trust anchors.
dotenv
Load configuration and secrets from .env files into process.env at startup, with multi-environment files, variable expansion, schema validation, and Node 20.6+ built-in --env-file alternatives.
DSPy
Build LLM programs in DSPy with declarative signatures, modules, and optimisers. Covers Predict, ChainOfThought, ReAct, BootstrapFewShot, COPRO, MIPRO, MIPROv2, and inference compilation.
Essential Python Packages
Overview of the 34 most useful Python packages — HTTP clients, data science, web frameworks, orchestration, testing, and tooling. Each has its own dedicated page with examples.
eza / exa
A modern ls replacement with colour coding, Git status, icons, tree view, and rich metadata. eza is the actively maintained fork of the original exa project.
fastapi
Build high-performance async REST APIs with FastAPI. Covers path params, request bodies, Pydantic models, dependency injection, and auto-generated OpenAPI docs.
Fastify
Fastify is a high-performance Node.js web framework with schema-driven validation, plugin encapsulation, hooks, decorators, and built-in Pino logging — covering routes, plugins, hooks, error handling, and production hardening.
fd
Modern find replacement written in Rust. Simpler syntax, respects .gitignore, supports regex and glob patterns, parallel execution, and coloured output.
Few-Shot Prompting
In-context learning techniques — example selection, format design, count tuning, dynamic retrieval of demonstrations, and pitfalls of few-shot prompting.
FFmpeg
Comprehensive FFmpeg reference covering transcoding, container conversion, scaling, filters, audio, subtitles, streaming, batch processing, and ffplay — with NVIDIA NVENC/NVDEC/CUDA alternatives, Vulkan compute codecs, VVC/H.266 decoding, and the FFmpeg 8.0 Whisper filter.
ffprobe
Comprehensive ffprobe reference for inspecting media files — formats, streams, frames, packets, chapters, metadata — with output formats (default, json, csv, xml, flat, ini), select_streams, show_entries, and one-liners for duration, fps, codec, resolution, and bitrate.
Filesystems
The OS-layer abstraction that turns a flat block device into named, permissioned, hierarchical files — covering inodes, paths, permissions, journaling, and copy-on-write.
Filesystems
Core filesystem concepts every operator should know: inodes, directory structure, hard vs symbolic links, journaling, copy-on-write, and a head-to-head of ext4, XFS, Btrfs, ZFS, APFS, and NTFS with mount options and pitfalls.
fish
Comprehensive fish shell reference covering syntax, variables, functions, abbreviations, completions, config files, path management, prompt customization, Fisher plugins, fish 4.x features (Rust rewrite), and migration from bash/zsh.
flask
Build lightweight web apps and REST APIs with Flask. Covers routes, request handling, JSON responses, blueprints, and the debug-server warning.
fzf
Interactive fuzzy finder for the terminal. Covers key bindings, shell integration, previews with bat and tree, multi-select, popup/tmux mode, --listen IPC, and pipelines with git, kill, and vim.
gh
Complete GitHub CLI reference. Auth, configuration, repos, issues, pull requests, releases, Actions, attestations, projects, models, rulesets, caches, secrets, gists, search, API, extensions, and codespaces.
git
Complete Git reference. Setup, staging, committing, branching, merging, rebasing, stashing, remotes, tags, log inspection, undoing mistakes, submodules, and power-user aliases.
Go Modules
Cheat sheets for Go modules from pkg.go.dev — web frameworks, CLI builders, config, ORMs, and more.
gpg
Practical GnuPG cheat sheet — generate keys, sign and verify files, encrypt for a recipient, sign git commits and tags, and manage trust without the bureaucracy.
grep
Search files and streams using fixed strings, extended regex, or PCRE. Covers all major flags, context, recursive search, and pipeline patterns.
Haystack 2.x
Build production-grade LLM pipelines with Haystack 2.x. Covers components, the pipeline graph, indexing and querying, retrievers, generators, RAG patterns, and evaluation.
htop
Interactive process and resource monitor for the terminal. Covers function keys, sorting, filtering, signal sending, tree view, threads, and how to read load averages and memory correctly. Compares with top, btop, and bottom.
HTTP
The request/response protocol that carries almost every API, page, and download on the modern internet — methods, status codes, headers, caching, and three wire formats (HTTP/1.1, HTTP/2, HTTP/3).
httpx
Make sync and async HTTP requests with httpx. Covers GET/POST, async usage, HTTP/2, streaming, and how it compares to requests.
ImageMagick
Comprehensive ImageMagick 7 reference covering magick, identify, mogrify, composite, montage, format conversion, resize, crop, rotate, color adjustments, effects, drawing, text, PDF operations, policy.xml hardening, and batch processing.
infer Keyword
TypeScript's infer keyword declares a fresh type variable inside a conditional type, letting you pull a sub-type out of a matched shape. It powers ReturnType, Parameters, Awaited, and most advanced type extractors.
ip
Modern replacement for ifconfig, route, and arp. Inspect and configure interfaces, addresses, routes, neighbour tables, and network namespaces with the iproute2 ip command.
itertools & functools
The two stdlib modules every Python developer pairs together — iterator algebra (chain, groupby, batched, pairwise) and function plumbing (lru_cache, partial, reduce, singledispatch, cached_property).
journalctl
Query and follow systemd's structured journal. Covers unit filters, time ranges, priority levels, boot logs, namespaces, invocations, output formats, persistence, configuration, and disk-vacuum.
jq
Slice, filter, map, and transform JSON data from the command line. Covers all essential filters, built-in functions, select, map, reduce, streaming, jq 1.7/1.8 additions, and real-world API response processing.
json
Encode and decode JSON in Python with the stdlib json module. Covers dumps/loads, indent/sort_keys/separators, custom default= and JSONEncoder, object_hook decoding, JSONL streaming, and orjson/ujson/msgspec comparison.
LLM Evaluations
Build production evaluation pipelines for LLM applications — golden datasets, LLM-as-judge, rubrics, statistical significance, regression detection, and evals vs tests.
logging
Configure Python's built-in logging module — loggers, handlers, formatters, dictConfig, rotation, structured records, and how it compares to loguru.
lsof & ss
Diagnose what's holding a port, which files a process has open, and the state of every TCP/UDP socket using lsof and the modern iproute2 ss utility.
make
Practical Makefile patterns: targets, prerequisites, automatic variables, pattern rules, parallel builds, and a working lint/test/build/clean workflow for any project.
MCP Frameworks
Model Context Protocol (MCP) framework overview. Covers client/server architecture, stdio vs SSE vs streamable HTTP transports, FastMCP, mcp-go, the Python and TypeScript SDKs, and comparison with custom tool servers.
Memory Management
How operating systems give every process its own address space: virtual memory and paging, swap, the OOM killer, mmap, copy-on-write, the page cache, allocator choices (glibc, jemalloc, mimalloc), and how to read memory counters in top, ps, and free.
Networking Stack
How packets actually move: the OSI and TCP/IP layer models, the BSD socket API, TCP vs UDP, the three-way handshake, MTU/MSS, NAT and port translation, basic IP routing, and the full DNS resolution flow.
node:fs
Node.js file system module — the three APIs (callback, sync, promises), reading and writing files, directory operations, watchers, atomic writes, and path module pairing.
node:stream
Node.js streams — Readable, Writable, Duplex, and Transform, the modern pipeline() API, backpressure, async iterators, Web Streams interop, and patterns for piping files, HTTP bodies, and gzip compression.
npm Packages
Cheat sheets for Node.js modules from the npm registry — HTTP clients, validation, CLI builders, utility libraries, and more.
Packages
Cheat sheets for individual libraries and modules across language ecosystems — pip, npm, Cargo, and Go.
PCRE
PCRE2 syntax reference — character classes, quantifiers, anchors, groups, lookarounds, backreferences, flags, and advanced features used in grep, sed, nginx, PHP, and dozens of other tools.
pdb
Pause, inspect, and step through Python programs with pdb. Covers breakpoint(), command reference, post-mortem debugging, conditional breakpoints, and enhanced alternatives like ipdb, pdbpp, and pudb.
permissions
POSIX file permissions on Linux. Covers symbolic and octal chmod, ownership with chown, the meaning of r/w/x for files vs. directories, setuid/setgid/sticky bits, umask, ACLs, capabilities, and immutable attributes.
Pip Packages
Cheat sheets for third-party PyPI packages — HTTP clients, data tools, validation, terminal UIs, and more.
pip vs uv
Side-by-side feature comparison of pip and uv — speed, lock files, virtual envs, Python version management, and when to use each.
Pipes
An operating-system primitive that streams one process's stdout into another's stdin, letting small composable tools build large data flows.
Playwright
Cross-browser end-to-end test runner from Microsoft with auto-waiting, role-based selectors, trace viewer, and codegen.
poetry
Manage Python project dependencies, virtual environments, and package publishing with Poetry. Covers pyproject.toml, lockfiles, groups, and publishing to PyPI.
pre-commit
Run linters, formatters, and validators automatically on every git commit. Covers .pre-commit-config.yaml, essential hooks (ruff, mypy, check-yaml), autoupdate, and CI integration.
Prisma
Schema-first ORM for Node.js with auto-generated typed client, declarative migrations, relations, transactions, and seeding — for PostgreSQL, MySQL, SQLite, MongoDB, and more.
Processes
Process lifecycle on Unix: fork/exec/wait, PIDs, signals, zombies and orphans, parent/child trees, process groups, sessions, controlling terminals, and a tour of Linux cgroups.
Prompt Engineering Patterns
Reliable prompt structures for reasoning, extraction, classification, generation, extended thinking, and vision tasks with Claude.
Prompting
Prompt engineering patterns, RAG, evaluations, few-shot, chain-of-thought, and structured output — foundational techniques for extracting reliable, structured behavior from LLMs.
ps, ss & netstat
Inspect running processes (ps), list network connections and listening ports (ss / netstat). Covers output formats, filtering, process trees, and socket state analysis.
pydantic
Validate and parse data at runtime using Python type hints with Pydantic v2. Covers BaseModel, field validators, nested models, and JSON serialization.
pyproject.toml
The canonical config file for modern Python projects — [project] metadata, [build-system] backends (setuptools, hatchling, pdm-backend, poetry-core, flit-core), [tool.*] sections, dynamic versioning, scripts, building, and publishing.
Python Installation
Install Python 3 on Debian/Ubuntu, Fedora/RHEL, and Arch Linux. Covers package managers, pyenv, and building from source for unsupported distros.
Python Installation
Install Python 3 on macOS via Homebrew or pyenv. Explains the system-Python warning, PATH precedence, and verification steps.
Python Installation
Install Python 3 on Windows via winget or the python.org installer. Covers PATH setup, the py launcher, and verification steps.
Python Installation
Install Python 3 inside WSL2/Ubuntu via apt, the deadsnakes PPA, or pyenv. Covers the python3-venv quirk and version aliasing.
Python Installation
Choose your OS and get Python installed in minutes. Covers Windows, WSL/Ubuntu, macOS, and Linux with recommended versions and verification steps.
qsv
Comprehensive reference for qsv: count, headers, stats, moarstats, select, search, sort, dedup, frequency, join, sqlp, luau, apply, schema, validate, sample, split, MCP server, and more — with examples and outputs.
RAG Implementation Checklist
End-to-end checklist and code for building reliable Retrieval-Augmented Generation pipelines — chunking, embedding, vector DBs, retrieval, and evaluation.
re
Python's built-in regex module — compile vs not, match/search/findall/finditer/sub, named groups, lookarounds, verbose mode (re.X), and how it differs from PCRE.
React Basics
Foundational React patterns — function components, JSX, props, hooks (useState, useEffect, useRef, useContext), list rendering, and form handling — with TypeScript throughout.
React with TypeScript
Type-safe React patterns — function components, prop types, children, event handlers, refs, generic components, polymorphic `as` props, and Zod-powered forms.
Regular Expressions
A pattern-matching mini-language for searching, validating, and rewriting text — implemented (with subtly different dialects) by every modern language and CLI tool.
requests
Make HTTP requests in Python with the requests library. Covers GET/POST, JSON, sessions, authentication, retries, and common pitfalls.
Retrieval-Augmented Generation (RAG)
Grounding LLM responses in chunks retrieved from an external corpus so the model reasons over real, citable sources instead of parametric memory alone.
ripgrep (rg)
Modern grep replacement written in Rust. Respects .gitignore, searches hidden files optionally, supports PCRE2, and is significantly faster on large codebases.
rsync
Copy and synchronise files locally or over SSH using a delta-transfer algorithm that only sends changed parts. Covers archive mode, deletion, filtering, progress, and snapshot backups.
satisfies Operator
TypeScript's satisfies operator checks a value against a type while preserving its narrow literal inferred type. The middle ground between an annotation that widens and an as cast that lies.
scikit-learn
Build classical ML pipelines with scikit-learn. Covers the estimator API, train_test_split, Pipeline, ColumnTransformer, cross-validation, metrics, and model persistence.
Security Fundamentals
OS-level security primitives every operator should know: users and groups, file permissions, Linux capabilities, SUID/SGID, mandatory access control (SELinux, AppArmor), sandboxing concepts, least privilege, and encryption at rest vs in transit.
sed
Non-interactive text transformation. Substitution, deletion, insertion, address ranges, in-place editing, and multi-line patterns with practical recipes.
Semantic Kernel
Build LLM-powered applications with Microsoft Semantic Kernel. Covers the kernel, plugins, prompt templates, planners, function calling, Kernel Memory, Python and .NET SDKs.
shellcheck
Catch quoting bugs, missing checks, and POSIX portability mistakes in shell scripts. Covers every flag, severity levels, inline directives, CI/pre-commit integration, and the most common rules.
SOLID
A modern walk-through of the SOLID principles — single responsibility, open-closed, Liskov, interface segregation, dependency inversion — with anti-examples and refactors in TypeScript and Python.
SoX
Comprehensive SoX reference covering file info, format conversion, synthesis, playback, recording, combining, effects (trim, reverb, compand, rate, pitch, tempo, noise gate), batch processing, spectrograms, and piping.
SSH Tunnels & Port Forwarding
Local, remote, and dynamic SSH tunnels — port forwarding, SOCKS proxies, jump hosts, ssh_config directives, agent forwarding, autossh persistence, post-quantum key exchange, and operational recipes.
streamlit
Build interactive web apps for data and ML in pure Python. Covers widgets, layout, session state, caching, multipage apps, and deployment patterns.
Structural Typing
Understand TypeScript's structural type system — assignability is based on shape, not name; excess property checks are the one exception; nominal typing requires branded types or class privates.
Structured Output
Techniques for reliable structured generation — JSON mode, schema-constrained decoding, function/tool calls as output, and validator pairing with Pydantic or Zod.
subprocess
Run external commands from Python with subprocess. Covers run vs Popen, capture_output, streaming, pipes, timeouts, env/cwd overrides, and shlex quoting safety.
systemd Unit Files
Writing, enabling, and managing systemd service, timer, and socket units.
tar
Bundle directory trees into a single archive file with optional compression. Covers create/extract/list, gzip/bzip2/xz formats, exclusions, transforms, and incremental backups.
Template Literal Types
Template literal types let TypeScript pattern-match and synthesize string types — covering Uppercase/Lowercase intrinsics, infer-based parsers (Split, Join, CamelCase), route-param extraction, JSON path keys, and typed i18n helpers.
Testing Strategies
A practical guide to test design — the pyramid (unit/integration/e2e), fixture and mock patterns, property-based testing, snapshot tests, and CI strategies that scale.
tmux
Run multiple persistent terminal sessions, windows, and panes inside one shell. Covers the session/window/pane mental model, default keybindings, copy-mode, and a minimal tmux.conf.
ts-node, tsx & Friends
Compare ts-node, tsx, Node 22.6+ --experimental-strip-types, Bun, and Deno for running .ts files directly; pick the right tool, configure watch mode, and avoid the classic ESM / type-strip pitfalls.
type-fest
Sindre Sorhus's collection of essential TypeScript utility types — PartialDeep, ReadonlyDeep, SetOptional, RequireAtLeastOne, Merge, Tagged, JsonValue, Opaque, and dozens more — so you don't hand-roll them.
typeof & keyof
TypeScript's typeof promotes a runtime value into the type position; keyof extracts the union of property keys. Together they form the backbone of type-safe lookups, enum-from-object patterns, and inferred shapes.
TypeScript Compiler API
Drive the TypeScript compiler programmatically — parse SourceFiles, query the type checker, transform ASTs with the factory, and write codemods that scale across a monorepo.
TypeScript Modules
Deep dive into TypeScript's module system — module/moduleResolution pairs, .mts/.cts file extensions, NodeNext vs Bundler resolution, paths, and tsconfig extends.
TypeScript Project References
Split a TypeScript codebase into composite sub-projects, build them incrementally in dependency order with tsc --build, and integrate the result with bundlers, Turborepo, and Nx.
typing
Go beyond list[int] and str | None. Covers Protocol, TypeVar bounds, ParamSpec, Concatenate, Self, Annotated, TypedDict with NotRequired/Required, TypeAlias, TypeGuard, TypeIs, cast, assert_type, and reveal_type.
uv
Install packages and manage virtual environments blazingly fast with uv. Covers uv pip, uv venv, uv run, uv init, and how it compares to pip and poetry.
vim
Bram Moolenaar's modal editor. Covers modes, verb-noun grammar, text objects, registers, marks, windows, search-and-replace, quickfix, macros, configuration, and a high-value baseline .vimrc.
Virtual Environments
Create, activate, and manage Python virtual environments with venv. Covers activation for every shell, pip usage, requirements files, and cleanup.
wget
Non-interactive network downloader. Covers single and batch downloads, recursive mirroring, authentication, resuming, rate limiting, and site archiving.
xidel Web Scraping & Data Extraction
Extract data from HTML, XML, and JSON using XPath, CSS selectors, pattern matching, and JSONiq from the command line.
Zod
TypeScript-first runtime validation library. Define schemas, validate inputs, infer static types — works at API boundaries, env config, forms, and tRPC.
05-24-2026
05-04-2026
05-02-2026
04-28-2026
04-27-2026
AI
Claude Code, Codex CLI, the Claude API, and prompt engineering — practical reference for building with and using large language models.
AutoGen
Build multi-agent AI systems with Microsoft AutoGen. Covers agents, group chats, code execution, tool registration, async runtimes, and LLM configuration.
ChromaDB
Store and query vector embeddings locally or over a network with ChromaDB. Covers client types, collections, add, query, metadata filters, embedding functions, and LangChain/LlamaIndex integration.
Codex CLI
OpenAI's open-source agentic coding CLI — installation, config.toml, slash commands, sandboxing, MCP integration, and AGENTS.md workflows.
crewAI
Orchestrate teams of role-playing AI agents with crewAI. Covers agents, tasks, crews, tools, LLM selection, memory, YAML config, and the kickoff lifecycle.
dagster
Build, schedule, and observe data pipelines as software-defined assets with Dagster. Covers assets, jobs, schedules, sensors, resources, partitions, and the Dagster UI.
DuckDB
Run fast analytical SQL queries in-process with DuckDB. Covers Python API, CSV/Parquet ingestion, pandas interop, Arrow, window functions, and persistent databases.
google-generativeai
Call Google's Gemini models from Python for text, multimodal, streaming, chat, function calling, and embeddings. Covers the genai SDK, safety settings, file API, and async usage.
guidance
Interleave Python control flow with LLM generation and enforce structured output using guidance. Covers gen(), select(), chat blocks, regex constraints, JSON schemas, and token healing.
LangChain
Build LLM-powered pipelines with LangChain. Covers LCEL chains, chat models, prompts, output parsers, tools, agents, retrievers, memory, and streaming.
LangSmith
Trace, debug, evaluate, and monitor LLM applications with LangSmith. Covers tracing setup, datasets, evaluators, prompt hub, comparing runs, and CI integration.
litestar
Build fast, type-safe HTTP APIs and web apps with Litestar. Covers route handlers, path/query/body params, DTOs, dependency injection, middleware, WebSockets, and OpenAPI.
LlamaIndex
Build RAG pipelines and LLM-powered data applications with LlamaIndex. Covers document loading, indexing, query engines, custom LLMs and embeddings, persistent storage, and agents.
modin
Speed up pandas workloads across all CPU cores with a one-line import swap. Covers Ray and Dask backends, config tuning, pandas interop, and when modin wins vs polars.
notebooklm-py
Automate Google NotebookLM from Python with the unofficial notebooklm-py library. Covers authentication, notebook and source management, summaries, FAQ generation, and audio podcast creation.
Operating Systems
Command-line references and tooling guides for Linux, Windows, z/OS, and macOS.
polars
High-performance DataFrames with a lazy expression API. Covers read/write, select, filter, group_by, joins, LazyFrame, datetime, string operations, and pandas interop.
prefect
Build, schedule, and observe Python workflows with Prefect. Covers flows, tasks, retries, schedules, deployments, caching, concurrency, and Prefect Cloud.
qdrant-client
Store and search vector embeddings with the Qdrant Python client. Covers collections, CRUD, filtered vector search, payload indexing, batch upsert, sparse/dense hybrid search, and integrations.
ragas
Measure and improve RAG pipeline quality with ragas. Covers faithfulness, answer relevancy, context precision, context recall, dataset format, LLM judges, and CI integration.
reflex
Build interactive web applications entirely in Python with Reflex. Covers state, components, events, pages, database, forms, and deployment.
SQLModel
Define database models with Python type hints using SQLModel. Covers table creation, CRUD, relationships, FastAPI integration, Pydantic validation, and async sessions.
tqdm
Add auto-updating progress bars to any Python loop or CLI pipeline with tqdm. Covers iterables, manual updates, pandas integration, nested bars, async, Jupyter, and byte-piping.
transformers
Load and run pre-trained models for NLP, vision, and audio with the Hugging Face Transformers library. Covers pipelines, AutoModel, tokenisation, generation, fine-tuning, and device placement.
TruLens
Evaluate and monitor LLM applications with TruLens. Covers the RAG triad, feedback functions, TruChain, TruLlama, custom evaluators, the dashboard, and CI integration.
typer
Build command-line interfaces using Python type annotations with Typer. Covers commands, options, arguments, subcommands, callbacks, rich output, and testing.
unstructured
Extract structured text from PDFs, Word docs, HTML, images, and more with the unstructured library. Covers partitioning, chunking, cleaning, metadata, and pipeline integrations.
weaviate-client
Store, search, and manage vector embeddings with the Weaviate Python client. Covers collections, CRUD, vector/hybrid/BM25 search, multi-tenancy, generative search, and batch import.
04-26-2026
Array Methods
JavaScript arrays have ~30 built-in methods for transforming, searching, and reducing data. Covers mutation, non-mutation, search, boolean, iteration, and static methods with real examples.
Async / Await
async/await syntax, error handling, parallel execution with Promise.all, sequential vs parallel loops, top-level await, AbortController, and common mistakes.
Common TypeScript Errors
A reference for the most frequent TypeScript compiler errors — their meaning, a minimal reproduction, and the correct fix. Covers TS2304, TS2345, TS2339, TS2322, TS2532, TS2554, TS2307, TS2366, TS7006, TS2571, TS2769, TS2693, plus type assertions and ts-expect-error.
Decorators
TypeScript decorators annotate and transform classes and class members. Covers the TC39 stage-3 standard decorators (TS 5.0+), legacy experimentalDecorators, decorator factories, method/class/field decorators, and reflect-metadata for NestJS and Angular patterns.
Enums
TypeScript enums create named constant sets as real runtime objects. Covers numeric, string, and const enums; reverse mapping; enum pitfalls; and when to prefer a union of string literals instead.
Error Handling
JavaScript error handling with try/catch/finally, built-in error types, custom error classes, error chaining with cause (ES2022), async errors, and practical patterns like result objects.
ESLint
The standard JavaScript/TypeScript linter. Covers flat config (v9), legacy .eslintrc, running, rules, plugins, TypeScript integration, VS Code, and pre-commit hooks.
Fetch API
The browser and Node 18+ built-in HTTP client that returns Promises. Covers GET/POST/PUT/DELETE, headers, error handling, streaming, AbortController, uploads, credentials, and CORS.
Generics
TypeScript generics allow writing reusable, type-safe code that works over many types. Covers generic functions, interfaces, classes, constraints, keyof, conditional types, and the infer keyword.
JavaScript
Node.js runtime, package managers, async patterns, array methods, and frontend tooling — a complete JavaScript reference for the command line and the browser.
JavaScript Modules
CommonJS vs ES Modules in Node.js — syntax, how Node chooses the module system, dynamic import, top-level await, CJS/ESM interop, and common pitfalls.
Mapped & Conditional Types
Mapped types iterate over type keys to create new types; conditional types pick between types based on a condition. Together they power all built-in utility types and advanced type composition.
Node.js Installation
Install Node.js on Windows, macOS, and Linux using winget, Homebrew, apt, nvm, Volta, or fnm. Covers version managers, LTS vs current, and verifying your install.
Node.js Runtime
How to use the Node.js runtime — REPL, running scripts, CLI flags, ESM vs CJS modules, built-in node: modules, the process object, and modern globals like fetch and structuredClone.
npm Package Manager
Complete npm reference — installing packages, scripts, workspaces, package.json anatomy, audit, publish, link, lockfiles, and registry configuration.
npx
Run npm package binaries without global installs using npx. Covers resolution order, version pinning, --yes, --no-install, npm exec, scaffolders, and cache management.
package.json Reference
Complete reference for the Node.js package manifest — name, version, scripts, dependencies, exports, workspaces, and the packageManager field for Corepack.
pip
Complete pip reference covering installation, package management, requirements files, private registries, caching, offline installs, and reproducible builds.
pnpm Package Manager
Fast, disk-efficient package manager using a content-addressable store and hard-links. Covers install, add, remove, scripts, dlx, exec, the pnpm store, and workspaces.
Prettier
Opinionated code formatter for JS/TS/CSS/HTML/JSON/Markdown. Covers config options, .prettierignore, VS Code integration, ESLint compatibility, lint-staged, and CI usage.
Programming
A reference hub for programming languages and their ecosystems — Python, JavaScript, and TypeScript, with package managers, runtimes, and tooling.
Promises
JavaScript Promises represent the eventual completion or failure of an async operation. Covers states, chaining, combinators, callback conversion, AbortController, and common anti-patterns.
Regular Expressions
JavaScript has built-in RegExp support (ES2018+ with named groups, lookbehind, dotAll). Covers literal syntax, flags, character classes, methods, named captures, and common patterns.
tsconfig.json Reference
Complete reference for tsconfig.json — compiler options for type checking, module resolution, output, paths, and JSX. Includes ready-to-use presets for Node 20, browser libraries, and Vite/React apps.
Type Guards
User-defined type guards narrow types at runtime using the `is` predicate, assertion functions, generic guards, and class-based patterns. Covers API validation, DOM guards, and when to use Zod.
Type Narrowing
TypeScript narrowing refines broad types to specific ones within code branches. Covers typeof, instanceof, in, equality, assignment narrowing, discriminated unions, control flow analysis, and the never type.
Type-Only Imports & Exports
import type and export type erase at compile time, preventing runtime side-effects and enabling better tree-shaking. Covers inline type qualifiers, verbatimModuleSyntax, and common gotchas with enums and namespaces.
Types vs Interfaces
TypeScript has two ways to define object shapes — type aliases and interface declarations. Learn when each is appropriate, how they differ in extension, merging, and composability.
TypeScript
Static typing for JavaScript — tsconfig reference, the full type system, generics, utility types, narrowing, and common compiler errors explained.
TypeScript Installation & Running
Install the TypeScript compiler, run .ts files without a build step using ts-node or tsx, and compile projects with tsc. Covers tsc flags, watch mode, and project references.
Utility Types
TypeScript's built-in generic utility types that transform existing types into new ones. Covers Partial, Required, Readonly, Record, Pick, Omit, Exclude, Extract, ReturnType, Awaited, and more.
Vite
Next-generation frontend build tool using native ES modules for near-instant dev server startup and Rollup for production bundles. Covers setup, config, HMR, env vars, assets, CSS, and plugins.
Vitest
Vite-native unit test framework with a Jest-compatible API. Covers setup, writing tests, matchers, mocking, timers, async testing, coverage, and UI mode.
Yarn Package Manager
Yarn is a fast, deterministic package manager from Meta. Covers Yarn Classic (v1) vs Yarn Berry (v4), install, add, remove, workspaces, Plug'n'Play, and migration tips.
04-25-2026
asyncio
Write concurrent Python code with asyncio. Covers coroutines, asyncio.run, gather, create_task, timeouts, queues, and avoiding the blocking-call pitfall.
black
Format Python code consistently with black. Covers installation, configuration, editor integration, and how it compares to ruff format.
click
Build command-line interfaces with click using decorators. Covers commands, options, arguments, groups, prompts, and progress bars.
django
Build database-driven web applications with Django. Covers project setup, models, migrations, the admin panel, views, forms, class-based views, middleware, signals, ORM advanced patterns, and the management command workflow.
jupyter
Run interactive Python notebooks with Jupyter. Covers JupyterLab setup, cell types, keyboard shortcuts, magic commands, nbconvert export, and common pitfalls.
loguru
Add structured, colorized logging to Python apps with loguru. Covers sinks, log levels, file rotation, retention, exception catching, and context binding.
matplotlib
Create publication-quality 2-D plots with matplotlib. Covers pyplot basics, subplots, savefig, common chart types, and the show-vs-save pitfall.
mypy
Catch type errors before runtime with mypy. Covers strict mode, common error codes, type: ignore annotations, gradual typing, and pyproject.toml configuration.
numpy
Create and manipulate N-dimensional arrays with NumPy. Covers array creation, broadcasting, vectorized math, indexing, and matrix operations.
pandas
Load, filter, transform, and aggregate tabular data with pandas. Covers DataFrame creation, read_csv, groupby, merge, and the SettingWithCopy pitfall.
pathlib
Work with filesystem paths using Python's built-in pathlib module. Covers Path creation, navigation, reading/writing files, glob patterns, and stat.
Pillow
Open, resize, crop, convert, and save images with Pillow (PIL fork). Covers format conversion, filters, drawing, and EXIF handling.
pytest
Write and run Python tests with pytest. Covers test discovery, assertions, fixtures, parametrize, conftest, and common patterns.
Python
Installation guides, essential packages, CLI snippets, and real-world recipes for Python 3.
Python CLI Snippets
Short standalone Python scripts for common tasks — file I/O, JSON manipulation, HTTP requests, CSV processing, and data transformation.
Python One-Liners
Useful Python one-liners runnable directly from the shell with python -c or python -m. No file creation needed.
rich
Make terminal output beautiful with Rich. Covers styled print, Console, tables, progress bars, syntax highlighting, live displays, and the rich-cli command.
ruff
Lint and format Python code with ruff — a single Rust-powered tool that replaces flake8, isort, and black. Covers configuration, rule selection, and CI usage.
scipy
Statistical distributions, optimization, integration, signal processing, and linear algebra with SciPy. Builds on NumPy arrays.
sqlalchemy
Connect to databases, write queries, and define ORM models with SQLAlchemy 2.0. Covers the engine, sessions, Core queries, ORM declarative models, relationships, session lifecycle, migrations with Alembic, and connection pool configuration.
04-24-2026
find
POSIX file finder with capable expression-based filters for name, type, size, time, permissions, and ownership. Covers exec actions, pruning, and real-world recipes.
macOS
Command-line tools, system utilities, Homebrew, Finder tricks, and macOS-specific development workflows.
sort, uniq & wc
Sort lines (numerically, by field, human-readable sizes), deduplicate with uniq, count lines/words/bytes with wc, and number lines with nl. With real-world pipeline recipes.
tr & xargs
Translate, squeeze, and delete characters with tr. Build and execute command lines from stdin with xargs. Includes parallel execution, NUL safety, and pipeline recipes.