/dotnet:install-sdk Skill

/dotnet:install-sdk

Install .NET SDK versions with cross-platform package manager support and interactive global.json configuration.

Arguments

Parse arguments from $ARGUMENTS:

| Flag | Description | Default | |------|-------------|---------| | --version <version> | SDK version to install (e.g., 10.0, 10.0.100) | Latest stable | | --update-global-json | Also update/create global.json | false | | --interactive | Interactive mode for global.json configuration | false | | --list | List installed SDKs | false | | --channel <channel> | Release channel (LTS, STS, Preview) | STS |

Workflow

Step 1: Detect Environment

Determine current state:

# Check installed SDKs
dotnet --list-sdks

# Check current global.json if exists
cat global.json 2>/dev/null || echo "No global.json"

Detect OS:

Windows: Check for winget availability
macOS: Check for brew availability
Linux: Check for apt, dnf, or pacman

Step 2: Determine Target Version

If --version specified:

Parse version (accept "10", "10.0", or "10.0.100")
Normalize to full SDK version

If --version not specified:

Query latest stable version:

Use mcp__perplexity__search:
  query: ".NET SDK latest stable version January 2026"

Step 3: Check If Already Installed

dotnet --list-sdks | grep "^<version>"

If already installed:

.NET SDK <version> is already installed.

Installed location: <path>
Current global.json: <version or none>

Would you like to:
- Update global.json to use this version
- Install a different version
- Exit

Step 4: Install SDK

Windows (winget):

winget install Microsoft.DotNet.SDK.<major> --version <version>

Windows (manual/chocolatey fallback):

# If winget not available
choco install dotnet-sdk --version=<version>

macOS (Homebrew):

# For latest
brew install --cask dotnet-sdk

# For specific version (if available)
brew install --cask dotnet-sdk@<major>

Linux (apt - Ubuntu/Debian):

# Add Microsoft package repository if needed
wget https://packages.microsoft.com/config/ubuntu/$(lsb_release -rs)/packages-microsoft-prod.deb
sudo dpkg -i packages-microsoft-prod.deb

# Install SDK
sudo apt-get update
sudo apt-get install -y dotnet-sdk-<major>.0

Linux (dnf - Fedora/RHEL):

sudo dnf install dotnet-sdk-<major>.0

Step 5: Verify Installation

dotnet --list-sdks
dotnet --version

Confirm the installed version appears in the list.

Step 6: Global.json Configuration

If --update-global-json or --interactive:

Interactive Mode (--interactive):

Present SDK selection:

Configure global.json for this project

Installed SDKs:
  1. 10.0.100 (just installed)
  2. 9.0.200
  3. 8.0.400

Which SDK version should this project use?

Then present rollForward policy:

Select rollForward policy:

  1. latestPatch (Recommended) - Use latest patch version
  2. latestMinor - Use latest minor version
  3. latestMajor - Use latest major version
  4. latestFeature - Use latest feature band
  5. disable - Use exact version only

Then present allowPrerelease:

Allow prerelease SDK versions?

  1. No (Recommended for production)
  2. Yes (For testing preview features)

Non-Interactive Mode:

Create/update global.json with sensible defaults:

{
  "sdk": {
    "version": "<installed-version>",
    "rollForward": "latestPatch"
  }
}

Step 7: Write Global.json

If global.json exists, preserve other settings:

{
  "sdk": {
    "version": "10.0.100",
    "rollForward": "latestPatch",
    "allowPrerelease": false
  },
  // Preserve existing msbuild-sdks, tools, etc.
}

Output Format

List Mode:

Installed .NET SDKs:

  Version     Location                              Status
  10.0.100    C:\Program Files\dotnet\sdk\10.0.100  Active (global.json)
  9.0.200     C:\Program Files\dotnet\sdk\9.0.200   Installed
  8.0.400     C:\Program Files\dotnet\sdk\8.0.400   Installed

Current global.json:
  Version: 10.0.100
  RollForward: latestPatch
  Path: D:\repos\myproject\global.json

Install Success:

.NET SDK Installation Complete

  Installed: .NET SDK 10.0.100
  Location: C:\Program Files\dotnet\sdk\10.0.100
  Method: winget

Verification:
  dotnet --version: 10.0.100

Global.json: Updated to use 10.0.100 with latestPatch rollForward

Install with Global.json Interactive:

.NET SDK Installation Complete

  Installed: .NET SDK 10.0.100

Global.json Configuration:
  {
    "sdk": {
      "version": "10.0.100",
      "rollForward": "latestMinor",
      "allowPrerelease": false
    }
  }

Written to: D:\repos\myproject\global.json

RollForward Policy Reference

| Policy | Behavior | |--------|----------| | patch | Exact patch version only | | feature | Latest patch, same feature band | | minor | Latest patch, same minor version | | major | Latest patch, same major version | | latestPatch | Latest patch of specified feature band | | latestFeature | Latest feature band of specified minor | | latestMinor | Latest minor of specified major | | latestMajor | Latest available SDK | | disable | Exact version only, no roll-forward |

Examples

# List installed SDKs
/dotnet:install-sdk --list

# Install latest stable SDK
/dotnet:install-sdk

# Install specific version
/dotnet:install-sdk --version 10.0.100

# Install and update global.json
/dotnet:install-sdk --version 10.0 --update-global-json

# Interactive global.json configuration
/dotnet:install-sdk --interactive

# Install preview SDK
/dotnet:install-sdk --channel Preview

Troubleshooting

winget not found (Windows):

winget is not available. Options:
1. Install App Installer from Microsoft Store
2. Use chocolatey: choco install dotnet-sdk
3. Download manually from https://dotnet.microsoft.com/download

Permission denied (Linux):

Installation requires sudo. Run:
  sudo apt-get install dotnet-sdk-10.0

Or use the install script (user-local):
  curl -sSL https://dot.net/v1/dotnet-install.sh | bash /dev/stdin --version 10.0.100

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