Question

How can I test in PowerShell code if a folder is a junction point?

Answer 1

Take a look at this blog:
https://web.archive.org/web/20190422210654/https://devblogs.microsoft.com/powershell/viewing-junctions-with-dir/

the way to do it is to copy the built in file system formatting file, modify it so that junctions are indicated, then load it with Update-FormatData:

From the Blog:

The file system formatting rules are
in $pshome\FileSystem.Format.ps1xml. I
copied this, then in the element
[ViewDefinitions –> View –> TableControl –> TableRowEntries –> TableRowEntry –> TableColumnItems –> TableColumnItem]
I changed the content
of PropertyName with value of ‘Mode’
to the following:

<ScriptBlock> 
   "$($_.Mode)$(if($_.Attributes -band [IO.FileAttributes]::ReparsePoint)
{'J'})" </ScriptBlock> 

This does a bitwise AND on the
DirectoryInfo object Attributes
property ($_.Attributes) against the
.Net System.IO.FileAttributes.ReparsePoint
enum value. If the result is not zero,
it displays a ‘J’ next to the other
file mode attributes. Next, load the
new formatting file like this:

 PS> Update-FormatData -PrependPath myFilesystem.format.ps1xml

The PrependPath parameter ensures that
the new formatting file is loaded
before the built-in formatting files.

Directory alink has a ‘J’ in the mode
column, seems to work!

It’s in the Mode column J for
Junction.