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How to invoke a PSCmdlet from within a PSCmdlet

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This example shows how to invoke a script based cmdlet or binary cmdlet inheriting from [System.Management.Automation.PSCmdlet] from within a binary cmdlet. In this example, the new cmdlet Get-ClipboardReverse calls Get-Clipboard to get the contents of the clipboard. The Get-ClipboardReverse reverses the order of the characters and returns the reversed string.

Note

The [PSCmdlet] class differs from the [Cmdlet] class. [PSCmdlet] implementations use runspace context information so you must invoke another cmdlet using the PowerShell pipeline API. In [Cmdlet] implementations you can call the cmdlet's .NET API directly. For an example, see How to invoke a Cmdlet from within a Cmdlet.

To invoke a cmdlet from within a PSCmdlet

  1. Ensure that the namespace for the [System.Management.Automation.PowerShell] API is referenced. In this example, the following namespaces are added.

    using System.Management.Automation;   // PowerShell assembly.
using System.Text;

  2. To invoke a command from within another binary cmdlet you must use the [PowerShell] API to construct a new pipeline and add the cmdlet to be invoked. Call the System.Management.Automation.PowerShell.Invoke<T>() method to invoke the pipeline.

    using var ps = PowerShell.Create(RunspaceMode.CurrentRunspace);
ps.AddCommand("Get-Clipboard").AddParameter("Raw");
var output = ps.Invoke<string>();

Example

To invoke a script based cmdlet or binary cmdlet inheriting from [PSCmdlet] you must build a PowerShell pipeline with the command and parameters you want to execute, then invoke the pipeline.

using System;
using System.Management.Automation;   // PowerShell assembly.
using System.Text;

namespace ClipboardReverse
{
    [Cmdlet(VerbsCommon.Get,"ClipboardReverse")]
    [OutputType(typeof(string))]
    public class ClipboardReverse : PSCmdlet
    {
        protected override void EndProcessing()
        {
            using var ps = PowerShell.Create(RunspaceMode.CurrentRunspace);
            ps.AddCommand("Get-Clipboard").AddParameter("Raw");
            var output = ps.Invoke<string>();
            if (ps.HadErrors)
            {
                WriteError(new ErrorRecord(ps.Streams.Error[0].Exception,
                           "Get-Clipboard Error", ErrorCategory.NotSpecified, null));
            }
            else
            {
                var sb = new StringBuilder();
                foreach (var text in output)
                {
                    sb.Append(text);
                }

                var reversed = sb.ToString().ToCharArray();
                Array.Reverse(reversed);
                WriteObject(new string(reversed));
            }
        }
    }
}

See Also

Writing a Windows PowerShell Cmdlet