Developer Command Cheatsheet

.gitignore syntax cheat sheet: wildcards, directory rules, negation (!), global ignores and templates for Node, Python.

A one-stop Linux troubleshooting reference organized by process/load, port/network, disk/memory, and logs/services, helping you quickly spot performance bottlenecks, connection anomalies, and resource hogs during live incidents.

Vim commands: motion, edit, search & replace, visual mode, save/exit, plus batch replace and sudo saves on servers.

Systemd service reference: start/stop, boot-enabling, journalctl log queries, timer scheduling, targets, resource limits, reload vs restart explained.

Cron schedules in five fields: use */5 for every five minutes, @daily for midnight runs, and crontab -e to edit while MAILTO routes task output.

A debugging reference for GitHub Actions, GitLab CI, and Jenkins pipelines, covering job reruns and log extraction, runner online status, cache and disk usage, and local reproduction with act or gitlab-runner exec.

An ES6+ syntax reference for frontend and full-stack developers: let/const, arrow functions, destructuring, template literals, higher-order array methods, and Promise/async-await — the patterns used most in everyday React/Vue and Node code, ready to reuse.

For Go developers building backend services, cloud-native tooling, and CLIs: covers variables & types, control flow, functions and defer, structs & methods, interfaces, goroutine/channel concurrency, and error handling, organized by the coding scenarios you hit in practice.

For Python developers doing data analysis, numerical computing, and scientific simulation: covers array creation, indexing & slicing, shape manipulation, math & statistics, random numbers, and the often-misunderstood broadcasting rule, arranged from creating an array to saving it to disk.

For Java backend and ops developers: covers compiling, running and packaging with javac/java/jar, Maven/Gradle build flows, JVM heap and GC tuning flags, and online troubleshooting with jps/jstack/jmap/jstat, organized in a build → run → tune → debug sequence you can copy.

For PHP developers and the ops people deploying PHP apps: covers running scripts and the built-in dev server, Composer dependency management, extension and ini config checks, php -l linting and phpinfo diagnostics, grouped by the real dev workflow.

For engineers working without a browser who need to call APIs and download with resumable transfers — covering GET/POST requests, headers & cookies, resumable download, proxy auth, and debugging with both curl and wget, plus a side-by-side comparison so you pick the right tool per task.

A curl request and troubleshooting handbook for backend developers, testers, and ops, covering GET/POST request bodies, -v/-I/-w request details and timing analysis, -k/-x TLS and proxies, -u/-F/-o auth and upload, plus practical combinations of cookies, redirects, and timeout retries.

An HTML reference for building accessible, semantic web pages — document structure, text, lists, links & images, tables, forms, and the semantic tags that convey meaning to both browsers and screen readers.

A CSS reference for styling pages without a framework, covering selectors, the box model, Flex/Grid layout, positioning, transitions & animation, and responsive patterns for both desktop and mobile.

An Emmet abbreviation reference for anyone writing HTML/CSS by hand in VSCode, covering structure expansion, nesting & grouping, attribute and counter shortcuts, and CSS shorthand that turns long markup into a single keystroke.

A MySQL command handbook for DBAs, backends, and data analysts, covering database & table management, CRUD, index optimization and slow-query localization with EXPLAIN, user privileges, logical backup & recovery, and replication — highlighting operations that can lock tables or stall replication.

A PostgreSQL command handbook for backend engineers, DBAs, and data analysts, covering connection & role management, database & table operations, EXPLAIN analysis, lock & transaction troubleshooting, pg_dump/pg_restore backup & recovery, and streaming replication, with paths for locating lock waits and table bloat.

40+ Redis commands: strings, hashes, lists, sets, expiry, persistence, memory, slowlog, cluster and replication.

A MongoDB reference for backend engineers, covering database & collection management, document CRUD, query operators, index strategies that keep queries off full collection scans, the aggregation pipeline, and replica-set vs sharded-cluster responsibilities.

Cypher for graph data in Neo4j: create nodes with CREATE, walk typed relationships with MATCH, match-or-create via MERGE, and index with CREATE INDEX.

A kubectl command handbook for app developers and cluster operators, covering Pod query & log diagnosis, deployment scaling & rolling updates, context & namespace switching, and event troubleshooting, with full debugging paths for CrashLoopBackOff and ImagePullBackOff.

A Docker Compose command handbook for frontend, backend, and DevOps engineers who manage several services as one unit, covering multi-service orchestration, log tracking & status inspection, config validation & build, network & named volume management, and horizontal scaling, with mitigation and troubleshooting for frequent incidents like down -v data loss and --scale port conflicts.

A Dockerfile writing reference for developers who package applications into images, covering base image selection, RUN execution, COPY/ADD file handling, ENV variables, port declaration, multi-stage builds, and layer size optimization — with the build cache and .dockerignore pitfalls that silently blow up image size.

HTTP methods and REST semantics: GET/POST/PUT/PATCH/DELETE verbs, idempotency, safe methods, status-code pairing and common misuses. For choosing the right verb when designing APIs so retries and concurrency behave predictably. Pairs with the HTTP Status Codes sheet.

Every HTTP response status code from 1xx to 5xx with its meaning, common cause and a debugging hint. Built for backend/frontend developers and Nginx/gateway ops to pinpoint why an API misbehaves — distinguishing 4xx from 5xx and checking whether redirects behave as expected.

A Markdown syntax reference covering headings, text formatting, links & images, lists, code blocks, tables, blockquotes and GFM extensions, with cross-platform caveats. For writing technical docs, READMEs and blog posts that stay clean and portable.

LaTeX commands for academic typesetting, grouped into document structure, text formatting, math formulas, list environments, tables/figures and references. For writing papers, reports and theses in LaTeX rather than fighting the tool.

ASCII codes for control and printable characters, each shown in decimal, hex, octal and HTML-entity forms, plus notes on Latin-1 extension and how to convert codes in common programming languages. For encoding and protocol debugging.

Emacs keystrokes covering file & buffer operations, cursor movement and editing, search/replace, window management, keyboard macros and Org-mode, with the C/M prefix conventions explained. For terminal or no-GUI editing where Vim-style modal editing is not an option.

Prompt-design patterns and templates for ChatGPT: role assignment, task framing and step breakdown, output-format constraints, few-shot examples and chain-of-thought steering — with common office, coding and writing scenarios. For turning vague asks into consistent, controllable model output.

Pandoc conversion commands across Markdown/HTML/PDF/DOCX/EPUB interchange, Chinese PDF typesetting and fonts, custom templates and styles, slides and e-books, citations and math. For converting documents without re-keying content or breaking layout.

Homebrew commands for installing/updating/removing formulas, managing Cask GUI apps, starting and stopping services, switching to domestic mirrors, and inspecting dependencies and debugging broken installs. For keeping a macOS dev environment reproducible.

XPath selector reference: node paths, predicates, axes, string and node functions, wildcards and operators, plus examples for HTML and XML scraping.

For developers shipping with Docker and slimming images: explains .dockerignore glob matching, ignoring files and directories, differences from .gitignore, build-context slimming tips and common pitfalls. A correct ignore file sharply shrinks the context sent to the daemon.

A YAML syntax reference for developers who write Docker Compose, Kubernetes and GitHub Actions configs, covering basic syntax, data types, lists, dicts, multiline strings, anchors and explicit type tags. Consult section by section while validating indentation and common write errors.

A JSON reference for frontend/backend developers who handle API payloads and JSON config, covering data types, objects, arrays, nesting, common API response patterns, and validation/formatting commands. Consult section by section when a key quotation, comma or nested brace causes an error.

TOML reference for Rust/Cargo, Hugo and Python pyproject.toml: basic types, date-time, strings, arrays, tables, arrays of tables, Cargo.toml example.

INI config syntax: write sections like [section] and key = value pairs, comment with ; or #, and watch parser quirks such as BOM and duplicate keys.

llamacpp how-to: llama-cli flags -m, -i, -ngl, -c, GGUF quantization picks and fixes for load and VRAM errors.

Full command reference for MLC-LLM mlc_llm CLI: chat interactive, serve local server, convert model, plus --device, --quantization, --model-lib flags, all matched to official docs.

Full command reference for LocalAI local-ai CLI: run and serve to start, models list/install/pull for management, api and finetune commands, all matched to official docs.

Full command reference for LM Studio lms CLI: status, ls and ps to list models, get to download, load and unload, server start, and terminal chat, all matched to official docs.

Full command reference for GPT Engineer gpte and gpt-engineer CLI: create projects, improve code with -i, --model selection, --steps workflows, and --temperature, all matched to official docs.

Retrieval-Augmented Generation (RAG) prompt patterns covering answer-only-from-context, cite sources, handle no-answer, fuse multi-passage evidence, and flag conflicts — emphasizing traceability and hallucination control.

Autonomous-agent system-prompt patterns covering goal/role definition, tool declarations, step-by-step decision loops, guardrails & permissions, error handling, and reflection — emphasizing control and safety.

Model-agnostic text-to-image (Midjourney/Stable Diffusion/SDXL) prompt structure covering subject, style & artists, composition & lens, light & material, negative prompts, and common params.

Code-generation prompt patterns covering requirement & context handoff, language/framework/version constraints, I/O contracts, edge cases & tests, and acceptance criteria — emphasizing compilable, runnable output.

Prompt-writing reference for DeepSeek that distinguishes the reasoning model R1 (deepseek-reasoner) from the chat model V3 (deepseek-chat), covering R1 hard rules (no system prompt, instructions in user, no few-shot, temperature 0.6) and V3 system-lock, few-shot, and JSON/function calling.

50+ Windows keyboard shortcuts: Win key combos, File Explorer, screenshots, window management and CMD/PowerShell.

40+ Chrome shortcuts: tabs, windows, browsing, address bar, DevTools and mouse, macOS ⇄ Windows side by side.

A Slack keyboard-shortcut reference for team members who rely on Slack across many channels and threads, covering Messages, Channels, Navigation, Search and Formatting — 20+ high-frequency bindings on macOS and Windows.