Pass variables into script block powershell

Question

I seem to have a lot of trouble understanding how to get this working. I am trying to gather all variables up front that way I can call psexec and pass those variables to it in a scriptblock.

The reason I am using psexec is due to the fact I have old 2003 servers without powershell installed. My goal was to have powershell multithread out against a list of servers in a text file and spawn processes in a manner below.

    #Gather info
    $servers = "test1234"
    $userName = Read-host "What is the user name?"
    $userPassword = Read-host "What is the user password?"

    $scriptBlockwork = {c:\scripts\message\psexec.exe "$servers" -u domain\$userName -p $userPassword -c InstallMShotfix.cmd -f InstallMShotfix.cmd}.GetNewClosure()
    & $scriptBlockwork
    echo $scriptBlockwork

Why does the script block not take the variables defined even when using .GetNewClosure()

Mathias R. Jessen · Accepted Answer · 2015-03-13 18:54:11Z

1

It's not entirely clear from your question in which order you want to bind the parameters, but for a proper closure:

$PartialInstaller = {
    param($servers)
    return {
        param($userName,$userPassword)
        c:\scripts\message\psexec.exe "$servers" -u domain\$userName -p $userPassword -c InstallMShotfix.cmd -f InstallMShotfix.cmd
    }.GetNewClosure()
}

$Installer = &$PartialInstaller $servers
$Result = &Installer "username","password"

Alternatively, the call operator (&) supports splatting as well:

$ScriptArguments = @{}
$ScriptArguments.servers = "test1234"
$ScriptArguments.userName = Read-host "What is the user name?"
$ScriptArguments.userPassword = Read-host "What is the user password?"

$Work = {
    param($servers,$userName,$userPassword)
    c:\scripts\message\psexec.exe "$servers" -u domain\$userName -p $userPassword -c InstallMShotfix.cmd -f InstallMShotfix.cmd
}

& $Work @ScriptArguments

edited Mar 13, 2015 at 18:54

answered Mar 13, 2015 at 15:23

Mathias R. Jessen

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2 Comments

james Over a year ago

With this if I i want to call $work, it would not & $work and @scriptsarguments . Trying something like

$work2= {$work = {{ param($server,$Credential)           echo $server $Credential | out-file C:\echoplease.txt -NoClobber}& $work $ScriptArguments}}  Invoke-Command -ComputerName localhost -AsJob -ScriptBlock $work2

Didnt seem to work

Mathias R. Jessen Over a year ago

Oh sorry, neglected to address your requirement for a proper Closure. My example must be very confusing then, I'll update it

mjolinor · Accepted Answer · 2015-03-13 15:19:17Z

0

Not sure why, but I've never been able to get .getnewclosure() to work for that.

Fortunately [scriptblock]::Create() provides an workaround:

#Gather info
    $servers = "test1234"
    $userName = Read-host "What is the user name?"
    $userPassword = Read-host "What is the user password?"

    $scriptBlockwork = 
    [scriptblock]::Create(@"
    c:\scripts\message\psexec.exe "$servers" -u domain\$userName -p $userPassword -c InstallMShotfix.cmd -f InstallMShotfix.cmd
"@)
    & $scriptBlockwork
    echo $scriptBlockwork

answered Mar 13, 2015 at 15:19

mjolinor

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Comments

Jeter-work · Accepted Answer · 2015-03-13 16:03:13Z

0

invoke-command on TechNet.

Example 2 and Example 5 are each similar to your example.

Example 3 and Example 4 would allow you to do it without psexec, but you'll need WinRM enabled on the remote machine. These are especially useful if you need to execute a number of commands.

Also research Get-Credential for prompting for authentification. Depending on the environment (information security policy in your organization, etc.), you may be able to store the credentials in a file (encrypted format) and reuse them in scripts. Bare minimum, you won't be passing admin credentials over the wire in the clear.

TL;DR Invoke-Command is your friend. Get-Credential is more secure than Read-Host.

$Credential = $get-credential
foreach ($Server in $Serverlist) {
    $scriptBlockwork = { psexec $Server -c InstallMShotfix.cmd -f InstallMShotfix.cmd }
    Invoke-Command -credential $Credential -scriptblock $scriptBlockwork
}

This will run your psexec command with the credentials you enter. They need the right to run psexec locally and to run the cmd file on the remote machine. Populate $Serverlist by reading in a text file or statically defining it above.

edited Mar 13, 2015 at 16:03

answered Mar 13, 2015 at 15:57

Jeter-work

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4 Comments

Jeter-work Over a year ago

Just as an aside, consider installing WMF on your 2003 servers, so you can simplify this to: Invoke-Command -ComputerName server01 -Credential domain01\user01 -ScriptBlock { InstallMShotfix.cmd } In this case Invoke-Command replaces psexec.

james Over a year ago

This will wait until each session is complete before proceeding, and not thread out. If i had 25 servers in that list it would take a long time to complete. Right?

CB. Over a year ago

@james I think that using the -asjob switch parameter in invoke-command can do the trick,

Jeter-work Over a year ago

I was worried because -asjob starts a PS job on the target computer. Documentation says "Remote" but it should say "target". The switch -asjob is not allowed without a target. But there's an easy workaround. Invoke-Command -ComputerName localhost -AsJob -ScriptBlock ...

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