Kill process tree programmatically in C#

This worked very nicely for me:

/// <summary>
/// Kill a process, and all of its children, grandchildren, etc.
/// </summary>
/// <param name="pid">Process ID.</param>
private static void KillProcessAndChildren(int pid)
{
    // Cannot close 'system idle process'.
    if (pid == 0)
    {
        return;
    }
    ManagementObjectSearcher searcher = new ManagementObjectSearcher
            ("Select * From Win32_Process Where ParentProcessID=" + pid);
    ManagementObjectCollection moc = searcher.Get();
    foreach (ManagementObject mo in moc)
    {
        KillProcessAndChildren(Convert.ToInt32(mo["ProcessID"]));
    }
    try
    {
        Process proc = Process.GetProcessById(pid);
        proc.Kill();
    }
    catch (ArgumentException)
    {
        // Process already exited.
    }
}

Update 2016-04-26

Tested on Visual Studio 2015 Update 2 on Win7 x64. Still works as well now as it did 3 years ago.

Update 2017-11-14

Added check for system idle process if (pid == 0)

Update 2018-03-02

Need to add a reference to the System.Management namespace, see comment from @MinimalTech below. If you have ReSharper installed, it will offer to do this for you automatically.

Update 2018-10-10

The most common use case for this is killing any child processes that our own C# process has started.

In this case, a better solution is to use Win32 calls within C# to make any spawned process a child process. This means that when the parent process exits, any child processes are automatically closed by Windows, which eliminates the need for the code above. Please let me know if you want me to post the code.

If anyone needs a dotnet core solution,

Dotnet core 3.0

process.Kill(true);

See official documentation

Dotnet core 2.0

For .Net 2.0 dotnet cli came up with an implementation based on taskill as mentioned above and recursive pgrep/kill for unix based systems. Full implementation can be found on github. Sadly, the class is internal so you'll have to copy it into your code base.

List Child processes (has to be done recursively):

$"pgrep -P {parentId}"

Kill on process:

$"kill -TERM {processId}"

You should call Process.CloseMainWindow() which will send a message to the main window of the process. Think of it as having the user click the "X" close button or File | Exit menu item.

It is safer to send a message to Internet Explorer to close itself down, than go and kill all its processes. Those processes could be doing anything and you need to let IE do its thing and finish before just killing it in the middle of doing something that may be important for future runs. This goes true for any program you kill.