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# Configuration
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Commands for managing yarn configuration, global packages, and development symlinks.
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## Capabilities
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### Configuration Management
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Manage yarn configuration settings at global and project levels.
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```bash { .api }
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yarn config set <key> <value> [options]    # Set configuration value
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yarn config get <key>                      # Get configuration value
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yarn config delete <key> [options]         # Delete configuration key
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yarn config list                           # List all configuration
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yarn config current                        # Show current effective configuration
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# Options:
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--global, -g             # Set global configuration (user-level)
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```
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**Usage Examples:**
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```bash
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# Set configuration values
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yarn config set registry https://registry.npmjs.org
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yarn config set cache-folder /tmp/yarn-cache
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yarn config set network-timeout 300000
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# Set global configuration
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yarn config set registry https://npm.company.com --global
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yarn config set ignore-engines true --global
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# Get configuration values
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yarn config get registry
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yarn config get cache-folder
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# List all configuration
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yarn config list
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# Show current effective configuration with sources
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yarn config current
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# Delete configuration
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yarn config delete registry
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yarn config delete network-timeout --global
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```
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### Common Configuration Options
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```bash { .api }
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# Registry settings
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yarn config set registry <url>                    # Default package registry
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yarn config set <scope>:registry <url>            # Registry for scoped packages
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# Cache settings  
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yarn config set cache-folder <path>               # Cache directory location
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yarn config set offline-mirror <path>             # Offline cache location
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# Network settings
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yarn config set network-timeout <ms>              # Network request timeout
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yarn config set network-concurrency <number>      # Concurrent network requests
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# Installation behavior
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yarn config set ignore-scripts <boolean>          # Skip lifecycle scripts
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yarn config set ignore-engines <boolean>          # Ignore engines field
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yarn config set ignore-platform <boolean>         # Ignore platform checks
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yarn config set flat <boolean>                    # Use flat dependency structure
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# Workspace settings
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yarn config set workspaces-experimental <boolean> # Enable workspace features
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```
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**Configuration Examples:**
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```bash
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# Corporate environment setup
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yarn config set registry https://npm.company.com
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yarn config set //npm.company.com/:_authToken ${NPM_TOKEN}
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yarn config set strict-ssl false
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# Development optimizations
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yarn config set network-timeout 600000
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yarn config set network-concurrency 16
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yarn config set cache-folder ~/.yarn-cache
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# Security settings
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yarn config set ignore-scripts true
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yarn config set audit-level moderate
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```
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### Global Package Management
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Manage globally installed packages.
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```bash { .api }
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yarn global add <package> [options]        # Install global package
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yarn global remove <package>               # Remove global package
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yarn global list [options]                 # List global packages
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yarn global upgrade [package] [options]    # Upgrade global packages
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yarn global bin                            # Show global bin directory
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# Options for add:
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--prefix <path>          # Install to specific prefix
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# Options for upgrade:
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--latest                 # Upgrade to latest version (ignore semver)
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```
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**Usage Examples:**
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```bash
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# Install global packages
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yarn global add yarn
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yarn global add @vue/cli
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yarn global add create-react-app
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yarn global add typescript
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# Remove global packages
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yarn global remove create-react-app
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yarn global remove @vue/cli
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# List global packages
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yarn global list
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yarn global list --depth=0
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# Upgrade global packages
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yarn global upgrade
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yarn global upgrade typescript
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# Upgrade to latest versions (ignoring semver)
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yarn global upgrade --latest
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yarn global upgrade typescript --latest
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# Show global bin directory
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yarn global bin
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# Add global bin to PATH
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export PATH="$(yarn global bin):$PATH"
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```
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**Global Package Location:**
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- **Linux/macOS**: `~/.config/yarn/global`
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- **Windows**: `%LOCALAPPDATA%\Yarn\config\global`
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- **Binaries**: `$(yarn global bin)` directory
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### Link Management
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Create and manage symlinks for local development.
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```bash { .api }
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yarn link [package]                        # Link package from current directory
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yarn unlink [package]                     # Unlink package
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```
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**Usage Examples:**
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```bash
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# In package directory - register for linking
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cd /path/to/my-package
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yarn link
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# In consumer project - link to registered package
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cd /path/to/my-project
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yarn link my-package
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# Unlink package
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yarn unlink my-package
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# In package directory - unregister from linking
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cd /path/to/my-package
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yarn unlink
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```
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**Link Workflow:**
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1. **Register package**: Run `yarn link` in package directory
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2. **Link consumer**: Run `yarn link <package-name>` in consumer project
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3. **Development**: Changes in package are immediately available in consumer
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4. **Unlink**: Run `yarn unlink <package-name>` to restore normal dependency
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**Link Registry Location:**
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- **Linux/macOS**: `~/.config/yarn/link`
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- **Windows**: `%LOCALAPPDATA%\Yarn\config\link`
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## Configuration Files
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### .yarnrc Configuration
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Project-level configuration file (`.yarnrc`):
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```bash
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# Registry configuration
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registry "https://npm.company.com"
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"@company:registry" "https://npm.company.com"
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# Cache settings
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cache-folder "/tmp/yarn-cache"
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offline-mirror "./offline-cache"
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# Network settings
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network-timeout 300000
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network-concurrency 8
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# Installation settings
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ignore-scripts true
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ignore-engines false
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flat false
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# Authentication
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"//npm.company.com/:_authToken" "${NPM_TOKEN}"
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```
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### Global Configuration
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Global configuration location:
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- **Linux/macOS**: `~/.yarnrc`
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- **Windows**: `%USERPROFILE%\.yarnrc`
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```bash
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# Global defaults
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registry "https://registry.npmjs.org"
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cache-folder "/Users/username/.yarn-cache"
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disable-self-update-check true
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ignore-engines true
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```
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### Environment Variables
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Yarn respects environment variables for configuration:
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```bash { .api }
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# Cache directory
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YARN_CACHE_FOLDER=/path/to/cache
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# Registry settings
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YARN_REGISTRY=https://registry.npmjs.org
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# Network settings
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YARN_NETWORK_TIMEOUT=300000
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YARN_NETWORK_CONCURRENCY=8
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# Disable features
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YARN_DISABLE_SELF_UPDATE_CHECK=true
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YARN_ENABLE_OFFLINE_MODE=true
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# Authentication
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NPM_CONFIG_REGISTRY=https://npm.company.com
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NPM_CONFIG__AUTH_TOKEN=${TOKEN}
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# HTTP proxy
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HTTP_PROXY=http://proxy.company.com:8080
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HTTPS_PROXY=https://proxy.company.com:8080
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```
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## Registry Configuration
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### Multiple Registries
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```bash
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# Default registry
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yarn config set registry https://registry.npmjs.org
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# Scoped registries
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yarn config set @company:registry https://npm.company.com
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yarn config set @internal:registry https://internal-npm.company.com
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# Authentication for each registry
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yarn config set //registry.npmjs.org/:_authToken ${NPM_TOKEN}
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yarn config set //npm.company.com/:_authToken ${COMPANY_TOKEN}
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```
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### Registry Authentication
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```bash
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# Token-based authentication
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yarn config set //registry.npmjs.org/:_authToken ${NPM_TOKEN}
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# Basic authentication (base64 encoded username:password)
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yarn config set //npm.company.com/:_auth ${BASE64_AUTH}
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# Username/password authentication
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yarn config set //npm.company.com/:username ${USERNAME}
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yarn config set //npm.company.com/:_password ${BASE64_PASSWORD}
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yarn config set //npm.company.com/:email ${EMAIL}
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```
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### SSL Configuration
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```bash
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# Disable SSL verification (not recommended for production)
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yarn config set strict-ssl false
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# Custom CA certificate
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yarn config set ca-file /path/to/ca-cert.pem
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# Custom certificate files
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yarn config set cert-file /path/to/client-cert.pem
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yarn config set key-file /path/to/client-key.pem
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```
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## Advanced Configuration
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### Workspace Configuration
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```bash
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# Enable workspace features
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yarn config set workspaces-experimental true
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# Workspace-specific settings
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yarn config set workspace-experimental true
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yarn config set workspace-tools true
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```
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### Cache Configuration
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```bash
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# Cache settings
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yarn config set cache-folder ~/.yarn-cache
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yarn config set offline-mirror ./offline-packages
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yarn config set disable-self-update-check true
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# Cache cleanup
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yarn config set cache-clean-interval 86400000  # 24 hours in ms
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```
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### Network Optimization
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```bash
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# Network performance
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yarn config set network-timeout 600000    # 10 minutes
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yarn config set network-concurrency 16    # Concurrent requests
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yarn config set child-concurrency 8       # Child processes
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# Retry settings
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yarn config set network-retry-count 3
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yarn config set network-retry-delay 1000
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```
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### Development Settings
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```bash
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# Development optimizations
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yarn config set save-prefix "~"           # Use tilde for version ranges
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yarn config set ignore-scripts false      # Allow lifecycle scripts
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yarn config set ignore-engines false      # Check engine compatibility
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yarn config set ignore-platform false     # Check platform compatibility
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# Workspace development
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yarn config set link-duplicates true      # Link duplicate packages
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yarn config set link-folder ~/.config/yarn/link  # Link registry location
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```
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## Configuration Hierarchy
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Yarn uses configuration in this priority order (highest to lowest):
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1. **Command line flags**: `--registry https://example.com`
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2. **Environment variables**: `YARN_REGISTRY=https://example.com`
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3. **Project .yarnrc**: `./.yarnrc` in project directory
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4. **Parent .yarnrc**: `../.yarnrc` (and up the directory tree)
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5. **Global .yarnrc**: `~/.yarnrc` (user home directory)
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6. **System .yarnrc**: `/etc/yarnrc` (system-wide, Linux/macOS only)
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7. **Built-in defaults**: Yarn's default configuration
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### Configuration Debugging
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```bash
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# Show effective configuration
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yarn config list
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# Show configuration sources
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yarn config list --verbose
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# Check specific configuration value
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yarn config get registry
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# Test configuration
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yarn install --verbose  # Shows which registry is being used
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```
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### Configuration Best Practices
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**Project .yarnrc:**
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```bash
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# Project-specific settings only
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registry "https://npm.company.com"
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"@company:registry" "https://npm.company.com"
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network-timeout 300000
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```
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**Global .yarnrc:**
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```bash
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# User preferences and defaults
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cache-folder "/Users/username/.yarn-cache"
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disable-self-update-check true
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network-concurrency 8
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save-prefix "^"
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```
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**Environment Variables (CI/CD):**
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```bash
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# In CI/CD environment
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export YARN_CACHE_FOLDER=/tmp/yarn-cache
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export YARN_REGISTRY=https://npm.company.com
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export YARN_DISABLE_SELF_UPDATE_CHECK=true
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export NPM_CONFIG__AUTH_TOKEN=${NPM_TOKEN}
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```