[powershell] How to Correctly Check if a Process is running and Stop it

What is the correct way of determining if a process is running, for example FireFox, and stopping it?

I did some looking around and the best way I found was this:

if((get-process "firefox" -ea SilentlyContinue) -eq $Null){ 
        echo "Not Running" 
}

else{ 
    echo "Running"
    Stop-Process -processname "firefox"
 }

Is this the ideal way of doing it? If not, what the correct way of doing so?

@jmp242 - the generic System.Object type does not contain the CloseMainWindow method, but statically casting the System.Diagnostics.Process type when collecting the ProcessList variable works for me. Updated code (from this answer) with this casting (and looping changed to use ForEach-Object) is below.

function Stop-Processes {
    param(
        [parameter(Mandatory=$true)] $processName,
                                     $timeout = 5
    )
    [System.Diagnostics.Process[]]$processList = Get-Process $processName -ErrorAction SilentlyContinue

    ForEach ($Process in $processList) {
        # Try gracefully first
        $Process.CloseMainWindow() | Out-Null
    }

    # Check the 'HasExited' property for each process
    for ($i = 0 ; $i -le $timeout; $i++) {
        $AllHaveExited = $True
        $processList | ForEach-Object {
            If (-NOT $_.HasExited) {
                $AllHaveExited = $False
            }                    
        }
        If ($AllHaveExited -eq $true){
            Return
        }
        Start-Sleep 1
    }
    # If graceful close has failed, loop through 'Stop-Process'
    $processList | ForEach-Object {
        If (Get-Process -ID $_.ID -ErrorAction SilentlyContinue) {
            Stop-Process -Id $_.ID -Force -Verbose
        }
    }
}

Thanks @Joey. It's what I am looking for.

I just bring some improvements:

• to take into account multiple processes
• to avoid reaching the timeout when all processes have terminated
• to package the whole in a function

function Stop-Processes {
    param(
        [parameter(Mandatory=$true)] $processName,
                                     $timeout = 5
    )
    $processList = Get-Process $processName -ErrorAction SilentlyContinue
    if ($processList) {
        # Try gracefully first
        $processList.CloseMainWindow() | Out-Null

        # Wait until all processes have terminated or until timeout
        for ($i = 0 ; $i -le $timeout; $i ++){
            $AllHaveExited = $True
            $processList | % {
                $process = $_
                If (!$process.HasExited){
                    $AllHaveExited = $False
                }                    
            }
            If ($AllHaveExited){
                Return
            }
            sleep 1
        }
        # Else: kill
        $processList | Stop-Process -Force        
    }
}

If you don't need to display exact result "running" / "not runnuning", you could simply:

ps notepad -ErrorAction SilentlyContinue | kill -PassThru

If the process was not running, you'll get no results. If it was running, you'll receive get-process output, and the process will be stopped.