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about_Remote_Variables.md

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ms.date schema locale keywords title
01/03/2018
2.0.0
en-us
powershell,cmdlet
about_Remote_Variables

About Remote Variables

SHORT DESCRIPTION

Explains how to use local and remote variables in remote commands.

LONG DESCRIPTION

You can use variables in commands that you run on remote computers. Simply assign a value to the variable and then use the variable in place of the value.

By default, the variables in remote commands are assumed to be defined in the session in which the command runs. You can also use variables that are defined in the local session, but you must identify them as local variables in the command.

USING REMOTE VARIABLES

PowerShell assumes that the variables used in remote commands are defined in the session in which the command runs.

In the following example, the $ps variable is defined in the temporary session in which the Get-WinEvent command runs.

Invoke-Command -ComputerName S1 -ScriptBlock {
  $ps = "Windows PowerShell"; Get-WinEvent -LogName $ps
}

Similarly, when the command runs in a persistent session (PSSession), the remote variable must be defined in the same PSSession.

$s = New-PSSession -ComputerName S1
Invoke-Command -ComputerName S1 -ScriptBlock {$ps = "Windows PowerShell"}
Invoke-Command -Session $s -ScriptBlock {Get-WinEvent -LogName $ps}

USING LOCAL VARIABLES

You can also use local variables in remote commands, but you must indicate that the variable is defined in the local session.

Beginning in Windows PowerShell 3.0, you can use the Using scope modifier to identify a local variable in a remote command.

The syntax of Using is as follows:

$Using:<VariableName>

In the following example, the $ps variable is created in the local session, but is used in the session in which the command runs. The Using scope modifier identifies $ps as a local variable.

$ps = "Windows PowerShell"
Invoke-Command -ComputerName S1 -ScriptBlock {
  Get-WinEvent -LogName $Using:ps
}

You can also use the Using scope modifier in PSSessions.

$s = New-PSSession -ComputerName S1
$ps = "Windows PowerShell"
Invoke-Command -Session $s -ScriptBlock {Get-WinEvent -LogName $Using:ps}

USING LOCAL VARIABLES IN WINDOWS POWERSHELL 2.0

You can use local variables in a remote command by defining parameters for the remote command and using the ArgumentList parameter of the Invoke-Command cmdlet to specify the local variable as the parameter value.

This command format is valid on Windows PowerShell 2.0 and later versions of Windows PowerShell and PowerShell Core.

  • Use the param keyword to define parameters for the remote command. The parameter names are placeholders that do not need to match the name of the local variable.

  • Use the parameters defined by the param keyword in the command.

  • Use the ArgumentList parameter of the Invoke-Command cmdlet to specify the local variable as the parameter value.

For example, the following commands define the $ps variable in the local session and then use it in a remote command. The command uses $log as the parameter name and the local variable, $ps, as its value.

$ps = "Windows PowerShell"
Invoke-Command -ComputerName S1 -ScriptBlock {
  param($log)
  Get-WinEvent -logname $log
} -ArgumentList $ps

SEE ALSO

about_Remote

about_PSSessions

about_Scopes

Invoke-Command

Enter-PSSession

New-PSSession