Detect number of processes running with the same name

Any ideas of how to write a function that returns the number of instances of a process is running?

Perhaps something like this?

function numInstances([string]$process)
{开发者_如何学JAVA
    $i = 0
    while(<we can get a new process with name $process>)
    {
        $i++
    }

    return $i
}

Edit: Started to write a function... It works for a single instance but it goes into an infinite loop if more than one instance is running:

function numInstances([string]$process)
{
$i = 0
$ids = @()
while(((get-process $process) | where {$ids -notcontains $_.ID}) -ne $null)
    {
    $ids += (get-process $process).ID
    $i++
    }

return $i
}

function numInstances([string]$process)
{
    @(get-process -ea silentlycontinue $process).count
}

EDIT: added the silently continue and array cast to work with zero and one processes.

This works for me:

function numInstances([string]$process)
{
    @(Get-Process $process -ErrorAction 0).Count
}

# 0
numInstances notepad

# 1
Start-Process notepad
numInstances notepad

# many
Start-Process notepad
numInstances notepad

Output:

0
1
2

Though it is simple there are two important points in this solution: 1) use -ErrorAction 0 (0 is the same as SilentlyContinue), so that it works well when there are no specified processes; 2) use the array operator @() so that it works when there is a single process instance.

Its much easier to use the built-in cmdlet group-object:

 get-process | Group-Object -Property ProcessName

There is a nice one-liner : (ps).count

(Get-Process | Where-Object {$_.Name -eq 'Chrome'}).count

This will return you the number of processes with same name running. you can add filters to further format your data.