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, $_) }
}

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