Redirection to 'NUL' failed: FileStream will not open Win32 devices

Question

I am trying to remove some verbosity from a choco install command within AppVeyor. Here is what I been trying (as suggested here):

if (Test-Path "C:/ProgramData/chocolatey/bin/swig.exe") {
    echo "using swig from cache"
} else {
    choco install swig > NUL
}

However it fails with:

Redirection to 'NUL' failed: FileStream will not open Win32 devices such as
disk partitions and tape drives. Avoid use of "\\.\" in the path.
At line:4 char:5
+     choco install swig > NUL
+     ~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidOperation: (:) [], RuntimeException
    + FullyQualifiedErrorId : RedirectionFailed

Command executed with exception: Redirection to 'NUL' failed: FileStream will not open Win32 devices such as disk partitions and tape drives. Avoid use of "\\.\" in the path.

So my question is there a way to suppress the verbosity of a choco install command within PowerShell on AppVeyor?

http://stackoverflow.com/questions/5260125/whats-the-better-cleaner-way-to-ignore-output-in-powershell — beatcracker, Dec 30 '15 at 13:04
Throwing this out there - you should add `-y` to the argument as it may fail to finish installing depending on the version of choco. — ferventcoder, Dec 30 '15 at 21:47

score 11 · Accepted Answer · answered Dec 30 '15 at 14:05

11

nul is batch syntax. In PowerShell you can use $null instead, as Mathias R. Jessen pointed out in his comment:

choco install swig > $null

Other options are piping into the Out-Null cmdlet, collecting the output in a variable, or casting it to void:

choco install swig | Out-Null
$dummy = choco install swig
[void](choco install swig)

answered Dec 30 '15 at 14:05

Ansgar Wiechers

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2

It is not specific to the shell. It is a valid native Win32 filename for the `NUL` device. But most of .NET does not allow them. – Michel de Ruiter Jan 06 '16 at 13:30

Redirection to 'NUL' failed: FileStream will not open Win32 devices

1 Answers1