Foreach try catch

2
votes

I have a file with a list of computers, I need to loop through that list and report if one is free. 

$list = get-content "pathtofile.txt"

foreach ($computer in $list) {
  try {
    quser /server:$computer
  } catch [System.Management.Automation.RemoteException] {
    Write-Host "$computer is free"
  }
}

Now it works, but I want the catch to grab the error message and change it to the mess of computer name is free.

At the moment it is still returning 

quser : No User exists for *
At line:5 char:5
+     quser /server:$computer
+     ~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (No User exists for *:String) [], RemoteException
    + FullyQualifiedErrorId : NativeCommandError

For computers that are free.

I was able to get the System.Management.Automation.RemoteException by running the quser command against a computer I know is free and then running $Error[0] | fl * -Force:

writeErrorStream      : True
PSMessageDetails      : 
Exception             : System.Management.Automation.RemoteException: No User exists for *
TargetObject          : No User exists for *
CategoryInfo          : NotSpecified: (No User exists for *:String) [], RemoteException
FullyQualifiedErrorId : NativeCommandError
ErrorDetails          : 
InvocationInfo        : System.Management.Automation.InvocationInfo
ScriptStackTrace      : at , : line 1
PipelineIterationInfo : {0, 0}

Which gave me the exception code.

Now I did look at Foreach error handling in Powershell which showed my code should be right so not sure why the catch is not working.

2
powershell

2 Answers

4
votes
try {
    $savePreference = $ErrorActionPreference
    $ErrorActionPreference = 'Stop'
    quser /server:$computer 2>&1
}

catch [System.Management.Automation.RemoteException] {
    Write-Host "$computer is free"
}

finally
{
    $ErrorActionPreference = $savePreference
}
2
votes

I usually do this:

$list = get-content "pathtofile.txt"

foreach ($computer in $list)
{
    try 
{
    quser /server:$computer
}
catch
{
    if ($Error.Exception -eq "System.Management.Automation.RemoteException: No User exists for *")
    {
        Write-Host "$computer is free"
    }
    else
    {
        throw $error
    }
}

}