Add Install-PowerShellAsDotNetTool.ps1

Author: SamErde

General/Install-PowerShellAsDotNetTool.ps1

@@ -0,0 +1,51 @@
+<#
+.SYNOPSIS
+    Install PowerShell as a .NET global tool, which does not require Administrator privileges.
+.DESCRIPTION
+    This script installs PowerShell as a .NET global tool, which does not require Administrator privileges. It begins by
+    downloading the required .NET Tool install script, which is then used to install PowerShell.
+.NOTES
+    Author: Sam Erde (@SamErde)
+    Date: 2025-02-12
+#>
+
+# Download the .NET CLI install script if it is not found.
+if ( (Get-Command -Name 'dotnet' -ErrorAction SilentlyContinue) ) {
+    Write-Verbose "dotnet is already installed."
+} else {
+    $DownloadPath = Join-Path -Path $env:TEMP -ChildPath 'dotnet-install.ps1'
+    try {
+        Invoke-WebRequest 'https://dot.net/v1/dotnet-install.ps1' -OutFile $DownloadPath
+        Unblock-File -Path $DownloadPath
+    } catch {
+        Write-Error "Failed to download dotnet-install.ps1 to '$DownloadPath'."
+        throw $_
+    }
+
+    # Install the dotnet tool. The script installs the latest LTS release by default.
+    # The current stable release is required for PowerShell 7.5, which depends on .NET 9.
+    # Need to add a check for the appropriate version of .NET.
+    try {
+        .$DownloadPath -InstallDir '~/.dotnet' -Channel 'STS' # use of 'Current' is deprecated.
+    } catch {
+        throw $_
+    }
+
+}
+
+dotnet dev-certs https --trust
+
+# Install PowerShell and add $HOME\.dotnet\tools to the PATH.
+# Need to add error handling for when the required version of .NET is missing.
+try {
+    dotnet tool install --global PowerShell
+    $env:PATH += ';' + [System.IO.Path]::Combine($HOME, '.dotnet', 'tools')
+} catch {
+    throw $_
+}
+
+# Clean up.
+Remove-Variable -Name DownloadPath
+if (Test-Path -Path DownloadPath) {
+    Remove-Item -Path $DownloadPath -Confirm:$false
+}