Windows10 / Powershell：使用Get-Childitem时如何使用-include参数？

Question

When using "-filter":

Get-ChildItem -file -filter "*.txt" | foreach-object { write-host $_.FullName Get-ChildItem -file -filter "*.txt" | foreach-object { write-host $_.FullName }

I get a listing of the 4 .txt files that's in the current folder.

I tried using "-include"

Get-ChildItem -file -include *.txt | foreach-object { write-host $_.FullName }
Get-ChildItem -file -include *txt | foreach-object { write-host $_.FullName }

and I get nothing. I tried with and without the "-file" parameter and it makes no difference.

I've looked at various guides/examples (ss64.com/TechNet and etc) and supposedly I am doing it right.

Any ideas what I could be doing wrong? Thanks!

Answer 1

From the Get-Help page for Get-ChildItem :

The -Include parameter is effective only when the command includes the -Recurse parameter or the path leads to the contents of a directory, such as C:\\Windows* , where the " * " wildcard character specifies the contents of the C:\\Windows directory.

You'll note that you don't get a syntax error if you specify -include and don't specify -recurse in spite of the fact that whatever it does is literally undefined. You'll also note that C:\\Windows* is not a normal wildcard expression for "all files in the C:\\Windows directory". It's a wildcard expression for "all items that start with 'Windows' in the C:\\ directory and may or may not have an extension". I have no idea what the authors of Get-ChildItem think this parameter is supposed to do. They've done a fantastically poor job of documenting it and implementing it.

Consequently, I avoid the -Include parameter as broken/badly documented. I don't know what it's supposed to do that -Filter doesn't. I've read articles about what it does exactly. It "passes the value to the underlying provider to filter at that level" in some manner. I don't know why they assume that a sysadmin will know what that really means. My understanding is that it's the difference between calling DirectoryInfo.GetFiles() on each directory item and calling DirectoryInfo.GetFiles('*.txt') on each directory item, but most sysadmins aren't going to know what that means. However, it's so oddly behaved that I don't trust it, so even though I am about 95% sure of what it does... I still never use it.

Instead, I just pipe to Where-Object :

Get-ChildItem -file | Where-Object Extension -eq '.txt' | [...]

Also note that Get-ChildItem is broken with -LiteralPath , -Recurse and -Include in some versions of PowerShell, and will instead return all items.

Compare:

Get-ChildItem -LiteralPath $PSHOME *.exe -Recurse # works
Get-ChildItem -Path $PSHOME -Include *.exe -Recurse # works
Get-ChildItem -LiteralPath $PSHOME -Include *.exe -Recurse # does NOT work

Issue reported here for v6.

Answer 2

These work for me without recursion:

Get-ChildItem -Path "C:\Users\Athom\Desktop\*.txt"


Get-ChildItem -Path ".\*.txt"

Or Just add the recursion parameter:

 Get-ChildItem -Include *.txt -Recurse