Suppress and handle stderr error output in PowerShell script

Question

I wanted to capture SMB shares using PowerShell, but this doesn't work

# Cannot use CIM as it throws up WinRM errors.
# Could maybe use if WinRM is configured on all clients, but this is not a given.
$cim = New-CimSession -ComputerName $hostname
$sharescim = Get-SmbShare -CimSession $cim

So this led me to another method using net view and this is fairly ok if the host is Windows

# This method uses net view to collect the share names (including hidden shares like C$) into an array
# https://www.itprotoday.com/powershell/view-all-shares-remote-machine-powershell
try { $netview = $(net view \\$hostname /all) | select -Skip 7 | ?{$_ -match 'disk*'} | %{$_ -match '^(.+?)\s+Disk*'|out-null ; $matches[1]} }
catch { $netview = "No shares found" }

So, if the host is Linux, I get an error, and as you can see, I am trying above to suppress that error with try / catch, but this fails.

Obviously, this is because 'net view' is CMD so is not controllable by try / catch. So my question is: how can I a) suppress the system error below?, and b) handle this error when it happens (ie throw a "This host is not responding to 'net view'" or something instead of the error)?

System error 53 has occurred.
The network path was not found.

Answer 1

Stderr (standard error) output from external programs is not integrated with PowerShell's error handling , primarily because this stream is not only used to communicate errors , but also status information.
(You should therefore only infer success vs. failure of an external-program call from its exit code , as reflected in $LASTEXTICODE ^[1] ).

However, you can redirect stderr output, and redirecting it to $null ( 2>$null ) silences it ^[2] :

$netview = net view \\$hostname /all 2>$null | ...
if (-not $netview) { $netview = 'No shares found' }

---

^{[1] Acting on a nonzero exit code, which by convention signals failure, is also not integrated into PowerShell's error handling as of v7.1, but fixing that is being proposed in this RFC .}

^{[2] Up to PowerShell 7.1.x, any 2> redirection unexpectedly also records the stderr lines in the automatic $Error collection. This problem has been corrected in v7.1
As an unfortunate side effect, in versions up to v7.0, a 2> redirection can also throw a script-terminating error if $ErrorActionPreference = 'Stop' happens to be in effect, if at least one stderr line is emitted.}