📖 Guide

YAML — Complete Reference

YAML syntax reference covering scalars, collections, anchors, multi-line strings, and common patterns.

58 commands across 9 categories

ScalarsStringsCollections (Sequences & Mappings)Nested StructuresAnchors & AliasesMulti-line StringsCommentsAdvanced TypesCommon Patterns

Scalars

CommandDescription
key: value
String scalar (unquoted)
count: 42
Integer scalar
price: 19.99
Float scalar
enabled: true
Boolean (true, false, yes, no)
value: null
Null value (null, ~, or omit value)
date: 2024-01-15
Date scalar (ISO 8601)
timestamp: 2024-01-15T10:30:00Z
Timestamp with timezone
octal: 0o755
Octal number (YAML 1.2)

Strings

CommandDescription
name: hello world
Plain (unquoted) string
name: "hello\nworld"
Double-quoted string (escape sequences processed)
name: 'it''s here'
Single-quoted string (no escapes, '' for literal ')
not_bool: "true"
Quote to force string type when value looks like bool/number
not_null: "null"
Quote to prevent null interpretation
colon: "key: value"
Quote strings containing special chars (:, #, etc.)
special: "line1\nline2\ttab"
Escape sequences: \n newline, \t tab, \\ backslash

Collections (Sequences & Mappings)

CommandDescription
fruits:\n - apple\n - banana
Block sequence (list)
fruits: [apple, banana, cherry]
Flow sequence (inline list)
person:\n name: Alice\n age: 30
Block mapping (dictionary)
person: {name: Alice, age: 30}
Flow mapping (inline dictionary)
-\n name: Alice\n age: 30
Sequence of mappings
matrix:\n - [1, 2, 3]\n - [4, 5, 6]
Sequence of sequences (2D array)
? [complex, key]\n: value
Complex mapping key (using ? indicator)

Nested Structures

CommandDescription
a:\n b:\n c: deep
Deeply nested mappings (2-space indent per level)
users:\n - name: Alice\n roles:\n - admin
Nested sequence inside sequence item
config:\n db:\n host: localhost\n port: 5432
Nested config structure
servers:\n - name: web\n ports: [80, 443]
Mixed block and flow styles
defaults: &defaults\n adapter: postgres\ndev:\n <<: *defaults\n database: dev_db
Merge key with nested override

Anchors & Aliases

CommandDescription
defaults: &defaults\n timeout: 30
Anchor — define a reusable node with &name
production: *defaults
Alias — reference anchored node with *name
<<: *defaults
Merge key — merge anchored mapping into current mapping
dev:\n <<: *defaults\n debug: true
Merge with override — local keys take precedence
items:\n - &first Apple\n - Banana\n - *first
Anchor and alias on scalar values
<<: [*defaults, *extras]
Merge multiple anchors (first match wins)

Multi-line Strings

CommandDescription
text: |\n Line 1\n Line 2
Literal block — preserves newlines
text: >\n Line 1\n Line 2
Folded block — joins lines with spaces
text: |+\n Line 1\n\n
Keep trailing newlines (+ chomping indicator)
text: |-\n Line 1
Strip final newline (- chomping indicator)
text: >-\n Long text\n continued here
Folded and stripped — single line, no trailing newline
text: |2\n Indented content
Explicit indentation indicator (2 spaces)
text: >\n Paragraph 1.\n\n Paragraph 2.
Folded with blank line — preserves paragraph breaks

Comments

CommandDescription
# This is a comment
Full-line comment
key: value # inline comment
Inline comment (space before # required)
# Section header\n# ==============
Comment blocks for document organization
key: "value # not a comment"
# inside quotes is not a comment
# TODO: fix this later
Convention — use TODO/FIXME/NOTE prefixes

Advanced Types

CommandDescription
---
Document start marker
...
Document end marker
---\ndoc1\n---\ndoc2
Multiple documents in one file
binary: !!binary aGVsbG8=
Binary data (base64 encoded)
not_date: !!str 2024-01-15
Explicit type tag — force string
set: !!set\n ? item1\n ? item2
Set type (unique values only)
pairs: !!pairs\n - key1: val1\n - key2: val2
Ordered pairs type

Common Patterns

CommandDescription
env:\n DATABASE_URL: postgres://...
Environment variables mapping
services:\n web:\n image: nginx\n ports:\n - "80:80"
Docker Compose service definition
name: my-app\nversion: 1.0.0\ndependencies:\n - name: lib\n version: ^2.0
Package manifest pattern
on:\n push:\n branches: [main]\njobs:\n build:\n runs-on: ubuntu-latest
GitHub Actions workflow structure
apiVersion: v1\nkind: ConfigMap\nmetadata:\n name: config
Kubernetes resource pattern
spring:\n profiles:\n active: dev\n datasource:\n url: jdbc:...
Spring Boot application.yml pattern

More Guides

🌿
Git Commands
Complete Git command reference — from basics to advanced workflows. Searchable, with examples.
📝
Vim Commands
Complete Vim/Vi command reference — modes, motions, editing, search, and advanced features.
🐳
Docker Commands
Complete Docker & Docker Compose command reference — containers, images, volumes, networks, and orchestration.
🔤
Regex Reference
Complete regular expression reference — syntax, patterns, quantifiers, groups, lookaheads, and common recipes.
🐧
Linux Commands
Complete Linux/Bash command reference — file management, text processing, networking, system admin, and shell scripting.
☸️
Kubernetes Commands
Complete Kubernetes & kubectl command reference — pods, deployments, services, configmaps, and cluster management.
🐍
Python Reference
Complete Python reference — syntax, data structures, string methods, file I/O, comprehensions, and common patterns.
🗃️
SQL Reference
Complete SQL reference — queries, joins, aggregation, subqueries, indexes, and database management.
🌐
Nginx Reference
Complete Nginx configuration reference — server blocks, locations, proxying, SSL, load balancing, and caching.
🔐
SSH Commands
Complete SSH reference — connections, key management, tunneling, config, SCP/SFTP, and security hardening.
👷
Jenkins Reference
Complete Jenkins reference — pipeline syntax, Jenkinsfile, plugins, CLI, agents, and CI/CD patterns.
📨
HTTP Headers Reference
Complete HTTP headers reference — request headers, response headers, caching, security, CORS, and content negotiation. Searchable, with examples.
🐘
PostgreSQL Reference
Comprehensive PostgreSQL reference — from connection basics to advanced features like JSONB, full-text search, window functions, and performance tuning.
⚡
Async Patterns Reference
Multi-language async/concurrency patterns — JavaScript, Python, Go, Rust, Java, and universal concurrency patterns.
📡
Protobuf & gRPC Reference
Comprehensive reference for Protocol Buffers (proto3) and gRPC — message definitions, services, streaming, and common patterns.
📚
JS Array Methods
Complete JavaScript Array methods reference — creating, searching, transforming, sorting, iterating, and common patterns. Searchable, with examples.
🌊
Tailwind CSS Reference
Complete Tailwind CSS reference — layout, spacing, typography, colors, responsive design, states, and common patterns. Searchable, with examples.
◈
GraphQL Reference
Complete GraphQL reference — schema definition, types, queries, mutations, directives, fragments, and common patterns. Searchable, with examples.
💻
VS Code Shortcuts
Complete VS Code keyboard shortcuts — editing, navigation, search, multi-cursor, terminal, debug, and more. Searchable, with Cmd/Ctrl notation.
🔲
CSS Grid Reference
Complete CSS Grid reference — container properties, item placement, grid functions, and common layout patterns. Searchable, with examples.
📦
CSS Flexbox Reference
Complete CSS Flexbox reference — container properties, item properties, and common layout patterns. Searchable, with examples.
⚛️
React Hooks Reference
Complete React Hooks reference — useState, useEffect, useContext, custom hooks, and common patterns. Searchable, with examples.
🔷
TypeScript Reference
Complete TypeScript reference — types, interfaces, generics, utility types, and advanced patterns. Searchable, with examples.
☁️
AWS CLI Reference
Complete AWS CLI reference — EC2, S3, IAM, Lambda, ECS, RDS, CloudFormation, and common operations.
🐹
Go Reference
Complete Go (Golang) reference — syntax, types, functions, concurrency, error handling, and common patterns.
💠
PowerShell Reference
Complete PowerShell reference — cmdlets, pipelines, scripting, file operations, remote management, and Active Directory.
💾
Redis Commands
Complete Redis command reference — strings, hashes, lists, sets, sorted sets, pub/sub, transactions, and server management.
🏗️
Terraform Commands
Complete Terraform reference — init, plan, apply, state management, modules, workspaces, and HCL syntax.
⚙️
Ansible Commands
Complete Ansible reference — playbooks, modules, inventory, roles, vault, and ad-hoc commands.
🟨
JavaScript
Complete JavaScript reference — variables, types, operators, strings, arrays, objects, functions, async, DOM, ES6+, and more.
🎨
CSS
Complete CSS reference — selectors, box model, positioning, typography, animations, media queries, custom properties, and more.
📄
HTML
Complete HTML reference — document structure, text content, forms, media, semantic elements, accessibility, and more.
☕
Java
Complete Java reference — data types, strings, collections, OOP, interfaces, exceptions, file I/O, streams, lambdas, and more.
💻
Bash
Complete Bash reference — variables, strings, arrays, conditionals, loops, functions, file tests, I/O redirection, process management, and more.
🦀
Rust
Comprehensive Rust language cheat sheet covering ownership, traits, pattern matching, concurrency, and more.
📝
Markdown
Complete Markdown syntax reference for headings, formatting, links, tables, code blocks, and extensions.

📖 Free, searchable command reference. Bookmark this page for quick access.