Copy-Item by header & timestamp - powershell

Question

I am using the code below to filter out files depending on the headers in the file.
It works like a charm, but I have a problem with that it takes all the files in the $InputDirectory.
I would like to limit it so it only takes files that are 1-2 hours old.
There are two ways where I can get the date for this process.
Filename contains timestamp = XXXXXXXXXXX_XXXXXXXX_valuereport_YYYYMMDDhhmmss.csv
The timestamp the file was created (please note we are talking about 800K-1M files in the directory and more is added every hour, so the fastest way would be appreciated.
So how do I insert something in my code, so it besides the header, only takes files that are <1-2 hours old?
Sorry about the code example, I am new to this site and not sure how to get it in the right order.
Nothing yet.
foreach ($FilePath in (Get-ChildItem $InputDirectory -File) | Select-Object -ExpandProperty FullName) {
$Header = Get-Content $FilePath -First 1
# test for a string in the header line that distincts it from the other files
if ($Header -match ';energy,Wh,') {
# the substring ';energy,Wh,' defines this file as a 'HeatMeter' file
Copy-Item -Path $FilePath -Destination $OutputPathHeat
} elseif ($Header -match ';fabrication-no,,inst-value,0,0,0;datetime,,inst-value,0,0,0;volume,m3') {
# the substring ';datetime,,inst-value,0,0,0;volume,m3' defines this file as a 'WaterMeter' file
Copy-Item -Path $FilePath -Destination $OutputPathWater
} else {
# if all key substrings above did not match, move to the 'Other' directory
Copy-Item -Path $FilePath -Destination $OutputPathOther
}

Answer 1

There are several ways to filter a directory listing. The easiest way is to pipe the result of Get-ChildItem through Where-Object like:
Get-ChildItem -Path $InputDirectory -File |
Where-Object { $_.CreationTime -gt (Get-Date).AddHours(-2) } |
Select-Object -ExpandProperty FullName |
ForEach-Object {
$FilePath = $_
$Header = Get-Content $FilePath -First 1
# test for a string in the header line that distincts it from the other files
if ($Header -match ';energy,Wh,') {
# the substring ';energy,Wh,' defines this file as a 'HeatMeter' file
Copy-Item -Path $FilePath -Destination $OutputPathHeat
}
elseif ($Header -match ';fabrication-no,,inst-value,0,0,0;datetime,,inst-value,0,0,0;volume,m3') {
# the substring ';datetime,,inst-value,0,0,0;volume,m3' defines this file as a 'WaterMeter' file
Copy-Item -Path $FilePath -Destination $OutputPathWater
}
else {
# if all key substrings above did not match, move to the 'Other' directory
Copy-Item -Path $FilePath -Destination $OutputPathOther
}
}
It checks that the CreationTime is greater than now - 2h. Note that the last modified (LastWriteTime) timestamp may also be suitable for your use case.