StopProcessSample04 Sample
This sample shows how to write a cmdlet that declares parameter sets, specifies the default
parameter set, and can accept an input object. This cmdlet is similar to the Stop-Process cmdlet
provided by Windows PowerShell 2.0.
How to build the sample by using Visual Studio
With the Windows PowerShell 2.0 SDK installed, navigate to the StopProcessSample04 folder. The default location is
C:\Program Files (x86)\Microsoft SDKs\Windows\v7.0\Samples\sysmgmt\WindowsPowerShell\csharp\StopProcessSample04.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\StopProcessSample04Copy the sample assembly to the module folder.
Start Windows PowerShell.
Run the following command to load the assembly into Windows PowerShell:
Import-Module stopprossessample04Run 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.
Adding a parameter that accepts input object.
Adding parameters to parameter sets
Specifying the default parameter set.
Example
The following code shows an implementation of the Stop-Proc cmdlet that declare parameter sets, specifies the default parameter set, and can accept an input object.
This sample shows the input object, how to declare parameter sets, and how to specify the default parameter set to use.
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",
DefaultParameterSetName = "ProcessId",
SupportsShouldProcess = true)]
public class StopProcCommand : PSCmdlet
{
#region Parameters
/// <summary>
/// This parameter provides the list of process names on
/// which the Stop-Proc cmdlet will work.
/// </summary>
[Parameter(
Position = 0,
ParameterSetName = "ProcessName",
Mandatory = true,
ValueFromPipeline = true,
ValueFromPipelineByPropertyName = true,
HelpMessage = "The name of one or more processes to stop. Wildcards are permitted."
)]
[Alias("ProcessName")]
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(
HelpMessage = "If set the process(es) will be passed to the pipeline after stopped."
)]
public SwitchParameter PassThru
{
get { return passThru; }
set { passThru = value; }
}
private bool passThru;
/// This parameter provides the list of process identifiers on
/// which the Stop-Proc cmdlet will work.
[Parameter(
ParameterSetName = "ProcessId",
Mandatory = true,
ValueFromPipelineByPropertyName = true,
ValueFromPipeline = true
)]
[Alias("ProcessId")]
public int[] Id
{
get { return processIds; }
set { processIds = value; }
}
private int[] processIds;
/// <summary>
/// This parameter accepts an array of Process objects from the
/// the pipeline. This object contains the processes to stop.
/// </summary>
/// <value>Process objects</value>
[Parameter(
ParameterSetName = "InputObject",
Mandatory = true,
ValueFromPipeline = true)]
public Process[] InputObject
{
get { return inputObject; }
set { inputObject = value; }
}
private Process[] inputObject;
#endregion Parameters
#region CmdletOverrides
/// <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()
{
switch (ParameterSetName)
{
case "ProcessName":
ProcessByName();
break;
case "ProcessId":
ProcessById();
break;
case "InputObject":
foreach (Process process in inputObject)
{
SafeStopProcess(process);
}
break;
default:
throw new ArgumentException("Bad ParameterSet Name");
} // switch (ParameterSetName...
} // ProcessRecord
#endregion Cmdlet Overrides
#region Helper Methods
/// <summary>
/// Returns all processes with matching names.
/// </summary>
/// <param name="processName">
/// The name of the processes to return.
/// </param>
/// <param name="allProcesses">An array of all
/// computer processes.</param>
/// <returns>An array of matching processes.</returns>
internal ArrayList SafeGetProcessesByName(string processName,
ref ArrayList allProcesses)
{
// Create and array to store the matching processes.
ArrayList matchingProcesses = new ArrayList();
// Create the wildcard for pattern matching.
WildcardOptions options = WildcardOptions.IgnoreCase |
WildcardOptions.Compiled;
WildcardPattern wildcard = new WildcardPattern(processName, options);
// Walk all of the machine processes.
foreach(Process process in allProcesses)
{
string processNameToMatch = null;
try
{
processNameToMatch = process.ProcessName;
}
catch (Win32Exception e)
{
// Remove the process from the list so that it is not
// checked again.
allProcesses.Remove(process);
string message =
String.Format(CultureInfo.CurrentCulture, "The process \"{0}\" could not be found",
processName);
WriteVerbose(message);
WriteError(new ErrorRecord(e, "ProcessNotFound",
ErrorCategory.ObjectNotFound, processName));
continue;
}
if (!wildcard.IsMatch(processNameToMatch))
{
continue;
}
matchingProcesses.Add(process);
} // foreach(Process...
return matchingProcesses;
} // SafeGetProcessesByName
/// <summary>
/// Safely stops a named process. Used as standalone function
/// to declutter the ProcessRecord method.
/// </summary>
/// <param name="process">The process to stop.</param>
private void SafeStopProcess(Process process)
{
string processName = null;
try
{
processName = process.ProcessName;
}
catch (Win32Exception e)
{
WriteError(new ErrorRecord(e, "ProcessNotFound",
ErrorCategory.OpenError, processName));
return;
}
// 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)))
{
return;
}
// 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));
string message = null;
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))
{
return;
}
} // if (criticalProcess...
// Display a warning message if stopping a critical
// process.
if (criticalProcess)
{
message =
String.Format(CultureInfo.CurrentCulture,
"Stopping the critical process \"{0}\".",
processName);
WriteWarning(message);
} // if (criticalProcess...
try
{
// Stop the process.
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)
);
return;
} // if ((e is...
else throw;
} // catch
// Write a user-level verbose message to the pipeline. These 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,
"Stopped process \"{0}\", pid {1}.",
processName, process.Id);
WriteVerbose(message);
// If the PassThru parameter is specified, return the terminated
// process to the pipeline.
if (passThru)
{
// 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,
"Writing process \"{0}\" to pipeline",
processName);
WriteDebug(message);
WriteObject(process);
} // if (passThru..
} // SafeStopProcess
/// <summary>
/// Stop processes based on their names (using the
/// ParameterSetName as ProcessName)
/// </summary>
private void ProcessByName()
{
ArrayList allProcesses = null;
// Get a list of all processes.
try
{
allProcesses = new ArrayList(Process.GetProcesses());
}
catch (InvalidOperationException ioe)
{
base.ThrowTerminatingError(new ErrorRecord(
ioe, "UnableToAccessProcessList",
ErrorCategory.InvalidOperation, null));
}
// If a process name is passed to the cmdlet, get
// the associated processes.
// Write a non-terminating error for failure to
// retrieve a process.
foreach (string name in processNames)
{
// The allProcesses array list is passed as a reference because
// any process whose name cannot be obtained will be removed
// from the list so that its not compared the next time.
ArrayList processes =
SafeGetProcessesByName(name, ref allProcesses);
// If no processes were found write a non-
// terminating error.
if (processes.Count == 0)
{
WriteError(new ErrorRecord(
new Exception("Process not found."),
"ProcessNotFound",
ErrorCategory.ObjectNotFound,
name));
} // if (processes...
// Otherwise terminate all processes in the list.
else
{
foreach (Process process in processes)
{
SafeStopProcess(process);
} // foreach (Process...
} // else
} // foreach (string...
} // ProcessByName
/// <summary>
/// Stop processes based on their identifiers (using the
/// ParameterSetName as ProcessIds)
/// </summary>
internal void ProcessById()
{
foreach (int processId in processIds)
{
Process process = null;
try
{
process = Process.GetProcessById(processId);
// Write a debug message to the host that can be used
// when troubleshooting a problem. All debug messages
// will appear with the -Debug option
string message =
String.Format(CultureInfo.CurrentCulture,
"Acquired process for pid : {0}",
process.Id);
WriteDebug(message);
}
catch (ArgumentException ae)
{
string
message = String.Format(CultureInfo.CurrentCulture,
"The process id {0} could not be found",
processId);
WriteVerbose(message);
WriteError(new ErrorRecord(ae, "ProcessIdNotFound",
ErrorCategory.ObjectNotFound, processId));
continue;
}
SafeStopProcess(process);
} // foreach (int...
} // ProcessById
#endregion Helper Methods
#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", "calc" }
);
#endregion Private Data
} // StopProcCommand
#endregion StopProcCommand
}
See Also
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