A proof of concept PowerShell function to add a new profile to the Windows Terminal Preview (0.2.1831.0).

New-WindowsTerminalProfile.ps1

Function New-WindowsTerminalProfile {
    [cmdletbinding(SupportsShouldProcess)]
    Param(
        [Parameter(Position = 0, Mandatory)]
        [ValidateNotNullOrEmpty()]
        [alias("name")]
        [string]$ProfileName,
        [Parameter( Mandatory)]
        [ValidateNotNullOrEmpty()]
        [string]$Commandline,
        [string]$StartingDirectory,
        [ValidateSet("Campbell", "Solarized Light", "SolarizedDark", "One Half Dark", "One Half Light")]
        [string]$ColorScheme = "Campbell",
        [string]$FontFace = "Consolas",
        [int32]$FontSize = 10,
        [ValidateSet("bar", "emptyBox", "filledBox", "underscore", "vintage")]
        #cursor shape values are case sensitive
        [string]$CursorShape = "bar",
        [ValidatePattern("^#\w{6}$")]
        [string]$CursorColor = "#FFFFFF",
        [validateSet("PowerShell", "Linux", "CMD")]
        [string]$Icon = "PowerShell",
        [Validatescript( {Test-Path $_})]
        [string]$BackgroundImage,
        [ValidateSet("none", "fill", "uniform", "uniformtofill")]
        [string]$StretchMode = "uniform",
        [double]$Opacity = 0.9,
        [switch]$EnableOpacity
    )
    Begin {
        Write-Verbose "[$((Get-Date).TimeofDay) BEGIN  ] Starting $($myinvocation.mycommand)"
        #get the profiles.json file
        $Path = (Get-Childitem $env:localappdata\packages\Microsoft.WindowsTerminal*\profiles.json -Recurse).fullname
        Write-Verbose "[$((Get-Date).TimeofDay) BEGIN  ] Getting settings from $Path"
        #get the current settings
        $settings = Get-content -Path $path | ConvertFrom-Json

        #private helper function
        Function _getdatestamp {
            (Get-Date -format s).replace(":", "_")
        }
    } #begin

    Process {
        Write-Verbose "[$((Get-Date).TimeofDay) PROCESS] Creating terminal profile $ProfileName "
        Write-Verbose "[$((Get-Date).TimeofDay) PROCESS] Using icon for $icon"
        switch ($Icon) {

            "Powershell" { $iconpath = "ms-appx:///ProfileIcons/{61c54bbd-c2c6-5271-96e7-009a87ff44bf}.png"}
            "Linux" { $iconpath = "ms-appx:///ProfileIcons/{9acb9455-ca41-5af7-950f-6bca1bc9722f}.scale-100.png"}
            "CMD" { $iconpath = "ms-appx:///ProfileIcons/{0caa0dad-35be-5f56-a8ff-afceeeaa6101}.png"}
        }

        $guid = New-Guid

        $new = @{
            acrylicOpacity = $Opacity
            closeOnExit    = $True
            colorScheme    = $ColorScheme
            commandline    = $commandline
            cursorColor    = $CursorColor
            cursorShape    = $CursorShape
            fontFace       = $FontFace
            fontSize       = $FontSize
            guid           = "{$guid}"
            historySize    = 9001
            icon           = $iconPath
            name           = $ProfileName
            padding        = "0, 0, 0, 0"
            snapOnInput    = $True
            useAcrylic     = $EnableOpacity.ToBool()
        }

        if ($StartingDirectory) {
            Write-Verbose "[$((Get-Date).TimeofDay) PROCESS]  Setting Starting Directory to $StartingDirectory"
            #escape slashes in the path
            $new.add("startingDirectory", $StartingDirectory)
        }
        if ($BackgroundImage) {
            Write-Verbose "[$((Get-Date).TimeofDay) PROCESS] Adding background image $BackgroundImage"
            $new.Add("backgroundImage", $BackgroundImage)
            $new.Add("backgroundImageStretchMode", $StretchMode)
            $new.useAcrylic = $False
        }

        $newprof = New-Object -typename PSObject -property $new

        $settings.profiles += $newprof

        $out = [PSCustomobject]@{
            globals  = $settings.globals
            profiles = $settings.profiles
            schemes  = $settings.schemes
        }

        if ($pscmdlet.ShouldProcess($($newProf | Out-String))) {
            $parent = Split-Path -path $path
            $backpath = Join-Path -Path $parent -ChildPath "profiles_$(_getdatestamp).json"
            Write-Verbose "[$((Get-Date).TimeofDay) PROCESS] Creating a backup copy of $Path to $Backpath"

            Copy-item -path $path -Destination $backpath

            Write-Verbose "[$((Get-Date).TimeofDay) PROCESS] Writing updates to $Path"
            $out | ConvertTo-Json -depth 3  | Out-File -FilePath $path
        } #if should process
    } #process

    End {
        Write-Verbose "[$((Get-Date).TimeofDay) END    ] Ending $($myinvocation.mycommand)"
    } #end

} #close New-WindowsTerminalProfile

These are some of the things I'm thinking about, depending on what happens with the application.

• Going forward it would make sense to have many of these parameters take pipeline input by property name.
• Need to do more testing on the case-sensitivity of some of the values.
• I'd like a better way to get the current color schemes
• Offer a validation set for font family
• Need some parameter validation for parameters like font size and opacity

All of this may be duplicated effort. https://www.powershellgallery.com/packages/MSTerminalSettings/1.0.37-pre