How do I pass variables with the Invoke-Command cmdlet?

Question

I have to get Event-Logs from some servers and I don't want to read in the credentials for each server which is found.

I've tried to pass my variables by using the ArgumentList parameter but I doesn't work.

This is my code:

$User = Read-Host -Prompt "Enter Username"
$Password = Read-Host -Prompt "Enter Password" -AsSecureString
$BSTR = [System.Runtime.InteropServices.Marshal]::SecureStringToBSTR($Password)
$UnsecurePassword = [System.Runtime.InteropServices.Marshal]::PtrToStringAuto($BSTR)

Get-ADComputer -Filter "OperatingSystem -Like '*Server*'" | Sort-Object Name |
ForEach-Object{
    if($_.Name -like '*2008*'){
        Invoke-Command -ComputerName $_.Name -ArgumentList $User, $UnsecurePassword -ScriptBlock {  
            net use P: \\Server\dir1\dir2 /persistent:no /user:$User $UnsecurePassword
            Get-EventLog -LogName System -After (Get-Date).AddHours(-12) -EntryType Error, Warning | format-list | 
            out-file P:\EventLog_$env:COMPUTERNAME.log
            net use P: /delete /yes
        }
    }
}

How can I use the variables in the Invoke-Command ScriptBlock?

score 31 · Answer 1 · edited Nov 08 '21 at 16:19

31

Alternatively you can use the $Using:scope. See Example 5 under this link.

Example:

$servicesToSearchFor = "*"
Invoke-Command -ComputerName $computer -Credential (Get-Credential) -ScriptBlock { Get-Service $Using:servicesToSearchFor }

With $Using: you don't need the -ArgumentList parameter and the param block in the scriptblock.

edited Nov 08 '21 at 16:19

zett42

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answered Feb 07 '17 at 07:21

Moerwald

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1

This works WAY better than `param` and the like! Thank you! – Danijel-James W May 19 '20 at 10:13

score 9 · Accepted Answer · answered Mar 31 '16 at 09:15

Either you declare the parameters at the beginning of your scriptblock:

   {  
        param($user,$unsecurepassword)
        net use P: \\Server\dir1\dir2 /persistent:no /user:$User $UnsecurePassword
        Get-EventLog -LogName System -After (Get-Date).AddHours(-12) -EntryType Error, Warning | format-list | 
        out-file P:\EventLog_$env:COMPUTERNAME.log
        net use P: /delete /yes
    }

Or you acces your arguments using the $args variable:

#first passed parameter
$args[0]
#second passed parameter
$args[1]
....

Documentation: MSDN

Just make sure your variables in `param()` match up with the ones you pass in through the `-ArgumentList`. I learned that one the hard way when my $computer kept showing up as my user ID lol — nkasco, Mar 31 '16 at 12:26

score 0 · Answer 3 · answered Dec 21 '22 at 09:17

When you use ScriptBlock with Invoke-Command, all variables inside ScriptBlock are assumed to be defined in the remote session when it connected, so its not available on your current script block as an usual variable usagee form!

If you need to use a variable filled inside your script on the remote side, you should to use Using scope modifier to identify that local variable in a remote command environment.

See Example 9 on the: https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.core/invoke-command?view=powershell-7.3

change your code like these:

...
    ForEach-Object{
    if($_.Name -like '*2008*'){
        Invoke-Command -ComputerName $_.Name -ArgumentList $User, $UnsecurePassword -ScriptBlock {  
            net use P: \\Server\dir1\dir2 /persistent:no /user:$Using:User $Using:UnsecurePassword
            Get-EventLog -LogName System -After (Get-Date).AddHours(-12) -EntryType Error, Warning | format-list | 
            out-file P:\EventLog_$env:COMPUTERNAME.log
            net use P: /delete /yes
        }
    }

How do I pass variables with the Invoke-Command cmdlet?

3 Answers3

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