I want to pass a variable to a new console, but I don't know how.

$server = "server_name"
Start-Process Powershell {
      $host.ui.RawUI.WindowTitle = “Get-Process”
      Invoke-Command -ComputerName $server -ScriptBlock {
             Get-Process
      }
cmd /c pause
}

Error message:

Invoke-Command : Cannot validate argument on parameter 'ComputerName'. The argument is null or empty. Provide an argument that is not null or empty, and then try the command again

CodePudding user response：

if you want to use param-

info

param([type]$p1 = , [type]$p2 = , ...)

or:

info

param(
[string]$server 
)

Write-Host $a

./Test.ps1 "your server name"

CodePudding user response：

• Start-Process only accepts (one or more) strings as arguments, not a script block ({ ... }).

  • While a script block is accepted, it is simply stringified, which results in its verbatim content being passed as the argument (sans { and }), which means that $server is retained as-is (not expanded), and the child process that runs your command doesn't have a variable by that name defined, causing Invoke-Command to fail due not receiving a value for -ComputerName.

• Therefore, in order to incorporate variable values from the caller's scope, you must use string interpolation, using an expandable (double-quoted) string ("..."):

$server = "server_name"
# Parameters -FilePath and -ArgumentList are positionally implied.
# For the resulting powershell.exe call, -Command is implied.
Start-Process powershell "
  $host.ui.RawUI.WindowTitle = 'Get-Process'
  Invoke-Command -ComputerName $server -ScriptBlock { Get-Process }
  pause
"

A computer name ($server, in your case) doesn't contain spaces, but any variable values that do would require embedded enclosing quoting inside the overall "..." string, such as \`"$someVar\`" (`" escapes an " inside a "..." string in PowerShell, and the \ is additionally needed to escape the resulting verbatim " for the PowerShell CLI, powershell.exe).

For full robustness, additionally enclose the entire string value (implied -Command argument) in embedded "..." quoting ("`"...`"").

You can make this a bit easier by using the here-string form of an expandable string (@"<newline>...<newline>"@), inside of which you don't need to escape " chars.

Example of a fully robust call:

$someVar = 'A value with   spaces'
Start-Process powershell @"
  -NoProfile -Command "
    # Echo the value of $someVar
    Write-Output \"$someVar\"
    pause
  "
"@

Note the use of -NoProfile before -Command, which suppresses loading of the profile files, which can speed up the call and makes for a more predictable execution environment.