StopProcessSample02 Sample
This sample shows how to write a cmdlet that writes debug (WriteDebug), verbose (WriteVerbose), and
warning (WriteWarning) messages while stopping processes on the local computer. This cmdlet is
similar to the Stop-Process cmdlet provided by Windows PowerShell 2.0.
How to build the sample by using Visual Studio
Open Windows Internet Explorer and navigate to the StopProcessSample02 directory under the Samples directory.
With the Windows PowerShell 2.0 SDK installed, navigate to the StopProcessSample02 folder. The default location is
C:\Program Files (x86)\Microsoft SDKs\Windows\v7.0\Samples\sysmgmt\WindowsPowerShell\csharp\StopProcessSample02.Double-click the icon for the solution (.sln) file. This opens the sample project in Microsoft Visual Studio.
In the Build menu, select Build Solution to build the library for the sample in the default
\binor\bin\debugfolders.
How to run the sample
Create the following module folder:
[user]\Documents\WindowsPowerShell\Modules\StopProcessSample02Copy the sample assembly to the module folder.
Start Windows PowerShell.
Run the following command to load the assembly into Windows PowerShell:
Import-Module stopprossessample02Run the following command to run the cmdlet:
stop-proc
Requirements
This sample requires Windows PowerShell 2.0.
Demonstrates
This sample demonstrates the following.
Declaring a cmdlet class by using the Cmdlet attribute.
Declaring a cmdlet parameters by using the Parameter attribute.
Writing verbose messages. For more information about the method used to write verbose messages, see System.Management.Automation.Cmdlet.WriteVerbose.
Writing error messages. For more information about the method used to write error messages, see System.Management.Automation.Cmdlet.WriteError.
Writing warning messages. For more information about the method used to write warning messages, see System.Management.Automation.Cmdlet.WriteWarning.
Example
This sample shows how to write debug, verbose, and warning messages by using the WriteDebug,
WriteVerbose, and WriteWarning methods.
using System;
using System.Diagnostics;
using System.Collections;
using Win32Exception = System.ComponentModel.Win32Exception;
using System.Management.Automation; //Windows PowerShell namespace
using System.Globalization;
namespace Microsoft.Samples.PowerShell.Commands
{
#region StopProcCommand
/// <summary>
/// This class implements the stop-proc cmdlet.
/// </summary>
[Cmdlet(VerbsLifecycle.Stop, "Proc",
SupportsShouldProcess = true)]
public class StopProcCommand : Cmdlet
{
#region Parameters
/// <summary>
/// This parameter provides the list of process names on
/// which the Stop-Proc cmdlet will work.
/// </summary>
[Parameter(
Position = 0,
Mandatory = true,
ValueFromPipeline = true,
ValueFromPipelineByPropertyName = true
)]
public string[] Name
{
get { return processNames; }
set { processNames = value; }
}
private string[] processNames;
/// <summary>
/// This parameter overrides the ShouldContinue call to force
/// the cmdlet to stop its operation. This parameter should always
/// be used with caution.
/// </summary>
[Parameter]
public SwitchParameter Force
{
get { return force; }
set { force = value; }
}
private bool force;
/// <summary>
/// This parameter indicates that the cmdlet should return
/// an object to the pipeline after the processing has been
/// completed.
/// </summary>
[Parameter]
public SwitchParameter PassThru
{
get { return passThru; }
set { passThru = value; }
}
private bool passThru;
#endregion Parameters
#region Cmdlet Overrides
/// <summary>
/// The ProcessRecord method does the following for each of the
/// requested process names:
/// 1) Check that the process is not a critical process.
/// 2) Attempt to stop that process.
/// If no process is requested then nothing occurs.
/// </summary>
protected override void ProcessRecord()
{
foreach (string name in processNames)
{
string message = null;
// For every process name passed to the cmdlet, get the associated
// processes.
// Write a non-terminating error for failure to retrieve
// a process.
// Write a user-friendly verbose message to the pipeline. These
// messages are intended to give the user detailed information
// on the operations performed by the cmdlet. These messages will
// appear with the -Verbose option.
message = String.Format(CultureInfo.CurrentCulture,
"Attempting to stop process \"{0}\".", name);
WriteVerbose(message);
Process[] processes;
try
{
processes = Process.GetProcessesByName(name);
}
catch (InvalidOperationException ioe)
{
WriteError(new ErrorRecord(ioe,
"UnableToAccessProcessByName",
ErrorCategory.InvalidOperation,
name));
continue;
}
// Try to stop the processes that have been retrieved.
foreach (Process process in processes)
{
string processName;
try
{
processName = process.ProcessName;
}
catch (Win32Exception e)
{
WriteError(new ErrorRecord(e, "ProcessNameNotFound",
ErrorCategory.ObjectNotFound, process));
continue;
}
// Write a debug message to the host that can be used when
// troubleshooting a problem. All debug messages will appear
// with the -Debug option.
message = String.Format(CultureInfo.CurrentCulture,
"Acquired name for pid {0} : \"{1}\"",
process.Id, processName);
WriteDebug(message);
// Confirm the operation first.
// This is always false if the WhatIf parameter is specified.
if (!ShouldProcess(string.Format(CultureInfo.CurrentCulture,
"{0} ({1})",
processName, process.Id)))
{
continue;
}
// Make sure that the user really wants to stop a critical
// process that can possibly stop the computer.
bool criticalProcess = criticalProcessNames.Contains(processName.ToLower(CultureInfo.CurrentCulture));
if (criticalProcess && !force)
{
message = String.Format(CultureInfo.CurrentCulture,
"The process \"{0}\" is a critical process and should not be stopped. Are you sure you wish to stop the process?",
processName);
// It is possible that the ProcessRecord method is called
// multiple times when objects are received as inputs from
// the pipeline. So to retain YesToAll and NoToAll input that
// the user may enter across multiple calls to this function,
// they are stored as private members of the cmdlet.
if (!ShouldContinue(message, "Warning!",
ref yesToAll, ref noToAll))
{
continue;
}
} // if (criticalProcess...
// Display a warning message if the cmdlet is stopping a
// critical process.
if (criticalProcess)
{
message = String.Format(CultureInfo.CurrentCulture,
"Stopping the critical process \"{0}\".",
processName);
WriteWarning(message);
} // if (criticalProcess...
// Stop the named process.
try
{
process.Kill();
}
catch (Exception e)
{
if ((e is Win32Exception) || (e is SystemException) ||
(e is InvalidOperationException))
{
// This process could not be stopped so write
// a non-terminating error.
WriteError(new ErrorRecord(
e,
"CouldNotStopProcess",
ErrorCategory.CloseError,
process)
);
continue;
} // if ((e is...
else throw;
} // catch
message = String.Format(CultureInfo.CurrentCulture,
"Stopped process \"{0}\", pid {1}.",
processName, process.Id);
WriteVerbose(message);
// If the PassThru parameter is specified,
// return the terminated process object to the pipeline.
if (passThru)
{
message = String.Format(CultureInfo.CurrentCulture,
"Writing process \"{0}\" to pipeline",
processName);
WriteDebug(message);
WriteObject(process);
} // if (passThru...
} // foreach (Process...
} // foreach (string...
} // ProcessRecord
#endregion Cmdlet Overrides
#region Private Data
private bool yesToAll, noToAll;
/// <summary>
/// Partial list of critical processes that should not be
/// stopped. Lower case is used for case insensitive matching.
/// </summary>
private ArrayList criticalProcessNames = new ArrayList(
new string[] { "system", "winlogon", "spoolsv" }
);
#endregion Private Data
} // StopProcCommand
#endregion StopProcCommand
}
