Enable tab completion for ssh hostnames in PowerShell

profile-snippet-sshargcomplete.ps1

using namespace System.Management.Automation

Register-ArgumentCompleter -CommandName ssh,scp,sftp -Native -ScriptBlock {
    param($wordToComplete, $commandAst, $cursorPosition)
    $knownHosts = Get-Content ${Env:HOMEPATH}\.ssh\known_hosts `
    | ForEach-Object { ([string]$_).Split(' ')[0] } `
    | ForEach-Object { $_.Split(',') } `
    | Sort-Object -Unique

    # For now just assume it's a hostname.
    $textToComplete = $wordToComplete
    $generateCompletionText = {
        param($x)
        $x
    }
    if ($wordToComplete -match "^(?<user>[-\w/\\]+)@(?<host>[-.\w]+)$") {
        $textToComplete = $Matches["host"]
        $generateCompletionText = {
            param($hostname)
            $Matches["user"] + "@" + $hostname
        }
    }

    $knownHosts `
    | Where-Object { $_ -like "${textToComplete}*" } `
    | ForEach-Object { [CompletionResult]::new((&$generateCompletionText($_)), $_, [CompletionResultType]::ParameterValue, $_) }
}

Thank you so much everyone. This is my version that can read "Include" keyword recursively and support glob too

using namespace System.Management.Automation

Register-ArgumentCompleter -CommandName ssh,scp,sftp -Native -ScriptBlock {
	param($wordToComplete, $commandAst, $cursorPosition)

	function Get-SSHHostList($sshConfigPath) {
		Get-Content -Path $sshConfigPath `
		| Select-String -Pattern '^Host ' `
		| ForEach-Object { $_ -replace 'Host ', '' } `
		| ForEach-Object { $_ -split ' ' } `
		| Sort-Object -Unique `
		| Select-String -Pattern '^.*[*!?].*$' -NotMatch
	}
	
	function Get-SSHConfigFileList ($sshConfigFilePath) {
		$sshConfigDir = Split-Path -Path $sshConfigFilePath -Resolve -Parent
	
		$sshConfigFilePaths = @()
		$sshConfigFilePaths += $sshConfigFilePath
	
		$pathsPatterns = @()
		Get-Content -Path $sshConfigFilePath `
		| Select-String -Pattern '^Include ' `
		| ForEach-Object { $_ -replace 'Include ', '' }  `
		| ForEach-Object { $_ -replace '~', $Env:USERPROFILE } `
		| ForEach-Object { $_ -replace '\$Env:USERPROFILE', $Env:USERPROFILE } `
		| ForEach-Object { $_ -replace '\$Env:HOMEPATH', $Env:USERPROFILE } `
		| ForEach-Object { 
		$sshConfigFilePaths += $(Get-ChildItem -Path $sshConfigDir\$_ -File -ErrorAction SilentlyContinue -Force).FullName `
		| ForEach-Object { Get-SSHConfigFileList $_ } 
		}
	
		if (($sshConfigFilePaths.Length -eq 1) -and ($sshConfigFilePaths.item(0) -eq $sshConfigFilePath) ) {
			return $sshConfigFilePath
		}
	
		return $sshConfigFilePaths | Sort-Object -Unique
	}

	$sshPath = "$Env:USERPROFILE\.ssh"
	$hosts = Get-SSHConfigFileList "$sshPath\config" `
	| ForEach-Object { Get-SSHHostList $_ } `

	# For now just assume it's a hostname.
	$textToComplete = $wordToComplete
	$generateCompletionText = {
		param($x)
		$x
	}
	if ($wordToComplete -match "^(?<user>[-\w/\\]+)@(?<host>[-.\w]+)$") {
		$textToComplete = $Matches["host"]
		$generateCompletionText = {
			param($hostname)
			$Matches["user"] + "@" + $hostname
		}
	}

	$hosts `
	| Where-Object { $_ -like "${textToComplete}*" } `
	| ForEach-Object { [CompletionResult]::new((&$generateCompletionText($_)), $_, [CompletionResultType]::ParameterValue, $_) }
}

Thanks to all of you, this is my version that uses ~\.ssh\config, reads Include recursively, accepts multiple hosts per line, and filters out hosts with wildcards

Thanks @hoang-himself -- this snippet works perfectly for my use case, much appreciated.