Using variable in c# invocation of powershell

Question

I want to examine a MS service (with display name 'MyService', say) on a failover cluster and to this end I want to evaluate powershell commands in C#. The commands I have in mind are

$a = Get-ClusterResource "MyService"
$b = Get-ClusterGroup $a.OwnerGroup.Name | Get-ClusterResource | Where-Object {$_.ResourceType -eq "Network Name"}

I already figured out how to load the FailoverClusters module in to the power shell instance. I'm creating the shell using the following code:

InitialSessionState state = InitialSessionState.CreateDefault();
state.ImportPSModule(new[] { "FailoverClusters" });
PowerShell ps = PowerShell.Create(state);

With this psinstance I can now successfully execute single cluster evaluation commands.

Now my understanding is that if I'm using ps.AddCommand twice, first with Get-ClusterResource and then with the commands from the next line, I will pipe the result of Get-ClusterResource into the next command, which I don't want to do since the -Name parameter of Get-ClusterResource does not accept results from a pipe. (Rather the second line would be build using AddCommand)

My question is, how do I pass the variable $a to the second line in a c# powershell invoke? Do I have to create two power shell instances and evaluate the first line first, passing it's result somehow to a second call, or is it possible to define a variable in a programmatic powershell instance?

Eris · Accepted Answer · 2014-07-23 20:32:08Z

1

I'm pretty sure you just need to use AddParameter or AddArgument after adding the Get-ClusterResource command to the pipeline. AddParameter on MSDN.

Once you have the first pipeline added (only a single command in this case), use var result = ps.Invoke();, yank the required info from the result.Members collection, and use it to AddParameter or AddArgument after adding the Get-ClusterGroup

Then continue to use addCommand to fill in the rest of the pipeline.

The Powershell Invoke method has an example on msdn

(copy and pasted for posterity):

// Using the PowerShell object, call the Create() method 
// to create an empty pipeline, and then call the methods  
// needed to add the commands to the pipeline. Commands 
// parameters, and arguments are added in the order that the 
// methods are called.
PowerShell ps = PowerShell.Create();
ps.AddCommand("Get-Process");
ps.AddArgument("wmi*");
ps.AddCommand("Sort-Object");
ps.AddParameter("descending");
ps.AddArgument("id");

Console.WriteLine("Process               Id");
Console.WriteLine("------------------------");

// Call the Invoke() method to run the commands of 
// the pipeline synchronously.
foreach (PSObject result in ps.Invoke())
{
  Console.WriteLine("{0,-20}{1}",
          result.Members["ProcessName"].Value,
          result.Members["Id"].Value);
} // End foreach.

answered Jul 23, 2014 at 20:32

Eris

7,7281 gold badge33 silver badges46 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Thomas Over a year ago

Hi, thanks for answering, but, sorry, this does not address the point I wanted to make. I do know the example from MS you posted and I got this kind of command running. Your answer explains how to add parameters to a command. My question was about using variables (like $a) and how they behave in the pipeline. By now I figured out that the AddScript method does what I need, it allows the literal usage of the two lines I posted in the program.

Collectives™ on Stack Overflow

Using variable in c# invocation of powershell

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related