Recently I was to create a report via PowerShell about the *.inf files located in the C:\Windows\winsxs folder unsing the Filter parameter of Get-ChildItem (see the official documentation about this cmdlet and its parameters), like:
$infFiles = Get-ChildItem -Path C:\Windows\winsxs -Filter *.inf -Recurse
I've noticed it however, that files having other file extensions, like .inf_loc or .inf_dbf42768 are included in the result as well.
On the other hand, the Include parameter works as expected, returning only the .inf files:
$infFiles = Get-ChildItem -Path C:\Windows\winsxs -Include *.inf -Recurse
I've tested the phenomenon using PS version 3 and 4, and found, that if the extension you are looking for has exactly 3 character, than any files, those extensions begin with the same 3 character are returned, even if those files have a longer extension. If the extension you are looking for is shorter or longer than 3 characters, there is no such issue, at least, based on my experience.
Although performance is in my case not crucial, as far as I understand, using the Filter parameter would be more efficient, than the Include parameter, as it performs the filtering already on the provider level, as discussed in the cmdlet description:
Filters are more efficient than other parameters, because the provider applies them when retrieving the objects, rather than having Windows PowerShell filter the objects after they are retrieved.
and here:
...the –Filter parameter generates early, early filtering, whereas-Include is later early filtering! The performance difference between the two approaches turns out to be significant!
Is it a documented behaviour / bug? I've found something similar in the post mentioned before as well, but not in the official documentations.
