Tee-Object to two pipelines? - powershell

Question

I have the following code.
$summary = . {
while ($true) {
# Generating huge list of psobject
}
} |
Tee-Object -FilePath 'fname.csv' | # Need to process the input objects before writing to CSV
Group-Object -Property xxx | Select Name,Count
However, I need to process the input objects before writing to fname.csv. Is it possible to Tee the object to two pipelines?
I tried
$summary = . {
while ($true) {
# Generating huge list of psobject
}
} |
For-Each {
$_ | ConvertTo-Csv -NoTypeInformation | Out-File -Append 'file.csv'
$_
} |
Group-Object -Property xxx | Select Name,Count
But the headers are repeated every line in file.csv.

Answer 1

I'm not sure what you want to do. Does this help? The objects from get-process get passed to two different pipelines.
get-process cmd | foreach-object { $_ | measure-object
$_ | export-csv -append whatever.csv }

Answer 2

This should do the work in the question. It doesn't Tee to two pipelines, which may be needed for some use cases, though.
$summary = . {
while ($true) {
# Generating huge list of psobject
}
} |
ForEach {
$_ | Export-Csv -NoTypeInformation -Append 'file.csv'
$_
} |
Group-Object -Property xxx | Select Name,Count

Answer 3

Going after #mklement0 's guidance, does the below make it any simpler,
Get-Process excel | Tee-Object -Variable process | group processname | select name, count
$process | Export-Csv "D:\Op_GetProcessExcel.csv" -NoTypeInformation
Previous suggestion
As #AnsgarWiechers pointed out something like the following should work for you,
Get-Process |
group processname |
select name, count |
ConvertTo-Csv -NoTypeInformation |
Tee-Object "C:\Op_GetProcess.csv"