Question

I have a PowerShell script that uses du.exe (Disk Usage originally from Sysinternals) to calculate the size of directories.

If I run du c:\Backup in the console, it works as expected, but the same line of code run in ISE or PowerGui gives the expected result plus the error

+ du <<<<  c:\backup
+ CategoryInfo          : NotSpecified: (:String) [], RemoteException
+ FullyQualifiedErrorId : NativeCommandError

Why is that? How do I avoid this error? I tried invoke-expression, using &, but no go.

Thanks for the help.

Answer 1

To avoid this you can redirect stderr to null e.g.:

du 2> $null

Essentially the console host and ISE (as well as remoting) treat the stderr stream differently. On the console host it was important for PowerShell to support applications like edit.com to work along with other applications that write colored output and errors to the screen. If the I/O stream is not redirected on console host, PowerShell gives the native EXE a console handle to write to directly. This bypasses PowerShell so PowerShell can’t see that there are errors written so it can’t report the error via $error or by writing to PowerShell’s stderr stream.

ISE and remoting don’t need to support this scenario so they do see the errors on stderr and subsequently write the error and update $error.