Why do Powershell return as null when called from C# app code?

Question

I'm using this as a reference: http://msdn.microsoft.com/en-us/library/dd182449(v=VS.85).aspx

So the implementation is very similar. I'm executing the following PowerShell command to retrieve process information from the intended computer through the 1-liner command below:

$computer = "Remote.Computer.Here"; Get-Process -computer $computer | Sort-Object WorkingSet -desc | Select-Object -first 10 | Format-Table -property name, ID, @{Expression= {$_.WorkingSet/1mb};Label="MemoryLoad";} -auto

The command above executes perfectly in PS window. However, when called from C# app code, I get no returns. Especially so, when I access it through the following:

        PowerShell shell = PowerShell.Create();
        shell.AddScript(CmdletMap[PSVocab.OsProcLoad]);
        Collection<PSObject> obj = shell.Invoke();

        DataTable dt = new DataTable();
        dt.Columns.Add("ProcessName");
        dt.Columns.Add("ID");
        dt.Columns.Add("MemoryLoad");

        DataRow row;
        foreach (PSObject resultObject in obj)
        {
            row = dt.NewRow();
            row["ProcessName"] = resultObject.Members["name"].Value;
            row["ID"] = resultObject.Members["id"].Value;
            row["MemoryCol"] = resultObject.Members["MemoryLoad"].Value;

            dt.Rows.Add(row);
        }

Doing a quick-watch of resultObject.Members[].Value would simply return null.

Any help?

Thanks.

meta.stackexchange.com/questions/2950/…

Kiquenet
– Kiquenet

2013-03-06 10:01:38 +00:00
Commented Mar 6, 2013 at 10:01 — Kiquenet
– Kiquenet, Commented Mar 6, 2013 at 10:01

Keith Hill · Accepted Answer · 2011-07-19 20:45:10Z

2

Inspect shell.Streams.Error to see what error is happening with your invocation of the script.

answered Jul 19, 2011 at 20:45

Keith Hill

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Start-Automating · Accepted Answer · 2011-07-19 20:52:18Z

2

In PowerShell, the default for a failing operation is to return nothing. PowerShell has several well-known streams, and your error is either lying in the error stream ([PowerShell].Streams.Error) or it is a terminating error ([Powershell].InvocationStateInfo.Reason).

Hope this helps,

answered Jul 19, 2011 at 20:52

Start-Automating

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3 Comments

Jae Over a year ago

I inspected both for hints where the error might lie, however, both Streams.Error and InvocationStateInfo.Reason did not yield anything that would indicate there was an error. One thing I did find curious though is that if I add shell.AddCommand("Out-String") it would return the values.. only in string format. So it's definitely there, but being a pain to find than usual.

Start-Automating Over a year ago

You should try looking @ psobject.immediateBaseObject instead of poking @ the property values thru the psobject (as your the code above does)

Kiquenet Over a year ago

meta.stackexchange.com/questions/2950/…

Roman Kuzmin · Accepted Answer · 2011-07-20 01:58:51Z

1

Use two slightly different commands: one for C# (and console) and another for console only.

For invoking from C# and console:

$computer = "."
Get-Process -computer $computer | Sort-Object WorkingSet -desc | Select-Object -first 10 |
Select-Object -property name, ID, @{Expression= {$_.WorkingSet/1mb};Label="MemoryLoad"}

For interactive host (i.e. console, ISE, etc.) with prettier look:

$computer = "."
Get-Process -computer $computer | Sort-Object WorkingSet -desc | Select-Object -first 10 |
Select-Object -property name, ID, @{Expression= {$_.WorkingSet/1mb};Label="MemoryLoad"} |
Format-Table -AutoSize

It is the Format-Table that makes problems in C#. Do not use it in C#. As for console, it should be the last command in the pipeline, it produces objects for printing, not for further use. Example: the first command shows two columns name and ID but the second command does not get any name properties:

Get-Process | Format-Table -property name, ID
Get-Process | Format-Table -property name, ID | Select-Object name

edited Jul 20, 2011 at 1:58

answered Jul 20, 2011 at 1:46

Roman Kuzmin

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1 Comment

JasonMArcher Over a year ago

This. Format-Table returns formatting objects that are only intended for the console's format handling. Use Select-Object instead.

surfasb · Accepted Answer · 2011-07-20 00:15:08Z

1

According to the Technet, your syntax is wrong. . .

http://technet.microsoft.com/en-us/library/dd347630.aspx

Syntax

Get-Process [[-Name] ] [-ComputerName ] [-FileVersionInfo] [-Module] []

Get-Process -Id [-ComputerName ] [-FileVersionInfo] [-Module] []

Get-Process -InputObject [-ComputerName ] [-FileVersionInfo] [-Module] []

Specifically, you need to use -computername, and not computer. And I have no idea what "Remote.Computer.Here" is. . .. you can use localhost.

edit

Nm, my coworker is an idiot. I just had to swap Remote.Computer.here with . and it looks all fine and dandy. See if that works.

edited Jul 20, 2011 at 0:15

answered Jul 19, 2011 at 20:48

surfasb

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2 Comments

Jae Over a year ago

using 'computer' was a typo on my part. As for using localhost, I already tried that, and the results would still be the same.

surfasb Over a year ago

Try a . instead of 'localhost'. Actually, I have to modify that script heavily to make it work. I'm not a powershell expert, but he said that script needs some work. . .

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