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, $_) }
}

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.

Awesome! It works perfectly! Thanks you! This reminds me to renew my Shell scripting

If you want to simplify the script and just want to use the host-aliases without the user@ part in your ssh command, you can use the following script:

using namespace System.Management.Automation

$script = {
  param($wordToComplete)    

  Get-Content ${Env:HOMEPATH}\.ssh\config `
    | Select-String -Pattern "^Host " `
    | ForEach-Object { $_ -replace "host ", "" -split " " } `
    | Sort-Object -Unique `
    | Where-Object { $_ -like "$wordToComplete*" } `
    | ForEach-Object { "$_" }
}

Register-ArgumentCompleter -CommandName ssh,scp,sftp -ScriptBlock $script

This autocompletes for example ssh du⭾ to ssh dummy which will internally calls ssh [email protected], given the following ~\.ssh\config:

Host dummy
  Hostname dummy.com
  User admin

To state the "obvious" but for new users (and for educational purposes) note that this script should be placed in your profile file e.g:

C:\Users\Bob\Documents\WindowsPowerShell\Microsoft.PowerShell_profile.ps1

If you have VS code installed you could run code $PROFILE and it should look like:

using namespace System.Management.Automation

# Any other imports you had before
Import-Module posh-sshell

# Then the SSH completion script
Register-ArgumentCompleter -CommandName ssh,scp,sftp -Native -ScriptBlock {
    param($wordToComplete, $commandAst, $cursorPosition)
    
    # ... rest of the script
}

# Any other stuff you had in your profile

i found this and it was a great starting point, thanks a lot to the people above :3
i then sunk a little too much time into enhancing it... so here's my version, complete with scp remote-path completion:

using namespace System.Management.Automation

function Get-SSH-Hosts {
	param (
		[string]$filename = "${env:USERPROFILE}\.ssh\config"
	)

	if ([System.IO.File]::Exists($filename)) {
		Get-Content $filename `
			| Select-String -Pattern '^(Include|Host) ' `
			| ForEach-Object {
				if ($_ -match '^Include ') {
					$included = (Join-Path $filename .. ($_ -replace '^Include ', '') -Resolve)
					Get-SSH-Hosts $included
				} elseif (!($_ -match '\*')) {
					($_ -replace '^Host ', '' -split ' ')[0]
				}
			} `
			| Select-Object -Unique
	}
}

function Get-SSH-KnownHosts {
	Get-Content ${env:USERPROFILE}\.ssh\known_hosts `
		| ForEach-Object { ([string]$_).Split(' ')[0] } `
		| ForEach-Object { $_.Split(',') }
}

Function Complete-SSH-Host {
	param($wordToComplete, $hosts, $generateCompletionText)

	$textToComplete = $wordToComplete
	# preserve username if specified; only complete hostname
	if ($wordToComplete -match '^(?<user>[-\w/\\]+)@(?<host>[-.\w]+)$') {
		$textToComplete = $Matches['host']
		$generateCompletionText = {
			param($hostname)
			"$($Matches['user'])@${hostname}:"
		}
	}

	$allMatches = @()

	$prefixMatch = @($hosts | Where-Object { $_ -like "${textToComplete}*" })
	$allMatches += $prefixMatch

	$substringMatch = @($hosts | Where-Object { $_ -notin $allMatches -and $_ -like "*${textToComplete}*" })
	$allMatches += $substringMatch

	$fuzzyMatchString = ($textToComplete.toCharArray() | Join-String -OutputPrefix '*' -Separator '*' -OutputSuffix '*')
	# not quite smart-casing, but matches with same case shall be offered first
	$fuzzyMatchCased = @($hosts | Where-Object { $_ -notin $allMatches -and $_ -clike $fuzzyMatchString })
	$allMatches += $fuzzyMatchCased
	$fuzzyMatchUncased = @($hosts | Where-Object { $_ -notin $allMatches -and $_ -like $fuzzyMatchString })
	$allMatches += $fuzzyMatchUncased

	$allMatches | ForEach-Object { [CompletionResult]::new((&$generateCompletionText($_)), $_, [CompletionResultType]::ParameterValue, $_) }
}

Register-ArgumentCompleter -CommandName ssh,sftp -Native -ScriptBlock {
	param($wordToComplete, $commandAst, $cursorPosition)
	$hosts = (Get-SSH-Hosts) + (Get-SSH-KnownHosts) | Sort-Object -Unique

	# for now just assume it's a hostname; no command completion
	$generateCompletionText = {
		param($x)
		$x
	}
	Complete-SSH-Host $wordToComplete $hosts $generateCompletionText
}

Register-ArgumentCompleter -CommandName scp -Native -ScriptBlock {
	param($wordToComplete, $commandAst, $cursorPosition)
	$hosts = (Get-SSH-Hosts) + (Get-SSH-KnownHosts) | Sort-Object -Unique

	if ($wordToComplete -match '^(?<remote>([-\w/\\]+@)?([-.\w]+)):(?<path>.*)$') {
		$remote = $Matches['remote']
		$pathPrefix = $Matches['path'] -replace "^'", "" -replace "([^\\])'$", '$1'
		$generateCompletionText = {
			param($path)

			$quotedPath = $path
			if ($quotedPath -match '\s' -and $quotedPath -notmatch "'") {
				$quotedPath = "`'$quotedPath`'"
			}
			"${remote}:${quotedPath}"
		}

		# 'Write-Host' here is a hack to make password/TOTP prompts appear on a new line
		$files = (Write-Host) + (ssh -oRemoteCommand=none $remote shopt -s dotglob`; ls -1dp "'${pathPrefix}'*")

		return $files `
			| ForEach-Object {
				[CompletionResult]::new((&$generateCompletionText($_)), $_, [CompletionResultType]::ParameterValue, $_)
			}
	}

	$generateCompletionText = {
		param($x)
		"${x}:"
	}
	Complete-SSH-Host $wordToComplete $hosts $generateCompletionText
}