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, $_) }
}

I works for me. Maybe you need to load PSReadLine, I'm not really sure.

Just adding a note. There are missing backticks ``` in the example. You need to add them at the end of every line begining with a pipe |.
I think that they have been removed by the markdown parser...

Here is the working version to auto complete the from the .ssh/config file.

using namespace System.Management.Automation

### SSH autocompletion
Function Get-Hosts($configFile) {
    Get-Content $configFile `
    | Select-String -Pattern "^Host " `
    | ForEach-Object { $_ -replace "host ", "" } `
    | Sort-Object -Unique `
}

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

    $sshDir = "${Env:HOMEPATH}\.ssh"

    $hosts = Get-Content "$sshDir\config" `
    | Select-String -Pattern "^Include " `
    | ForEach-Object { $_ -replace "include ", "" } `
    | ForEach-Object { Get-Hosts "$sshDir/$_" } `

    $hosts += Get-Hosts "$sshDir\config"
    $hosts = $hosts | 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
        }
    }

    $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

[Diagnostics.CodeAnalysis.SuppressMessageAttribute('PSReviewUnusedParameter', '')]
param()

function Get-SSHHost($sshConfigPath) {
  Get-Content -Path $sshConfigPath `
  | Select-String -Pattern '^Host ' `
  | ForEach-Object { $_ -replace 'Host ', '' } `
  | ForEach-Object { $_ -split ' ' } `
  | Sort-Object -Unique `
  | Select-String -Pattern '^.*[*!?].*$' -NotMatch
}

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

  $sshPath = "$env:USERPROFILE\.ssh"

  $hosts = Get-Content -Path "$sshPath\config" `
  | Select-String -Pattern '^Include ' `
  | ForEach-Object { $_ -replace 'Include ', '' }  `
  | ForEach-Object { Get-SSHHost "$sshPath/$_" }

  $hosts += Get-SSHHost "$sshPath\config"
  $hosts = $hosts | Sort-Object -Unique

  $hosts | Where-Object { $_ -like "$wordToComplete*" } `
  | ForEach-Object { $_ }
}

I don't use known_hosts and I don't understand why some people use it, but I made this anyway

[Diagnostics.CodeAnalysis.SuppressMessageAttribute('PSReviewUnusedParameter', '')]
param()

function Get-SSHKnownHost($sshKnownHostsPath) {
  Get-Content -Path $sshKnownHostsPath `
  | ForEach-Object { $_.split(' ')[0] } `
  | Sort-Object -Unique
}

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

  $hosts = Get-SSHKnownHost "$env:USERPROFILE\.ssh\known_hosts"

  if ($wordToComplete -match '^(?<user>[-\w/\\]+)@(?<host>[-.\w]+)$') {
    $hosts | Where-Object { $_ -like "$($Matches['host'].ToString())*" } `
    | ForEach-Object { "$($Matches['user'].ToString())@$_" }
  }
}

I imagine you can use both of these at the same time, but pattern matching must be changed.

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.