/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