Silently handle errors in powershell - powershell

Question

I am writing a troubleshooting script to determine which IP addresses in our Domain are accessible by WMI, and which are not. The script will read a list of input parameters (about 18,000 lines), and will output to a file the IP address and the username
IP address, Username
Problem is, when the WMI error is thrown, it writes to the file
IP address, Get-WmiObject : The RPC server is unavailable. .....numerous lines of error
I would like to make it such that when a WMI error it thrown, it writes the following
IP address, "WMI ERROR"
And here is the modified code for reference
#script_modified.ps1
$abc = $args
$startInfo = $NULL
$process = $NULL
$standardOut = $NULL
<#Previously created password file in C:\Script\cred.txt, read-host -assecurestring | convertfrom-securestring | out-file C:\Script\cred.txt#>
$password = get-content C:\Script\cred.txt | convertto-securestring
$a = Get-Content "C:\Script\test_input.txt"
foreach ($b in $a){
$startInfo = New-Object System.Diagnostics.ProcessStartInfo
$startInfo.FileName = "powershell.exe"
$startInfo.Arguments = "C:\script\script2.ps1 " + $b
$startInfo.RedirectStandardOutput = $true
$startInfo.UseShellExecute = $false
$startInfo.CreateNoWindow = $false
$startInfo.Username = "service.infosec"
$startInfo.Domain = "Central"
$startInfo.Password = $password
$process = New-Object System.Diagnostics.Process
$process.StartInfo = $startInfo
$process.Start() | Out-Null
$standardOut = $process.StandardOutput.ReadToEnd()
$process.WaitForExit()
# $standardOut should contain the results of "C:\script\script2.ps1"
Add-Content C:\script\list_of_computers_in_DOMAIN.log $b","$standardOut
}
EDIT
#Hyper Anthony
I updated my code to the following
try{
$process.StartInfo = $startInfo
}
catch{
$message = "WMI ERROR"
}
finally{
$process.WaitForExit()
Add-Content C:\script\list_of_computers_in_DOMAIN.log $b","$message
}
And I get following errors:
Exception calling "WaitForExit" with "0" argument(s): "No process is associated with this object."
At C:\script\script_modified.ps1:36 char:29
+ $process.WaitForExit <<<< ()
+ CategoryInfo : NotSpecified: (:) [], MethodInvocationException
+ FullyQualifiedErrorId : DotNetMethodException
How to fix?
EDIT:
Below is the updated code:
foreach ($b in $a){
$startInfo = New-Object System.Diagnostics.ProcessStartInfo
$startInfo.FileName = "powershell.exe"
...More Code...
$process = New-Object System.Diagnostics.Process
$process.StartInfo = $startInfo
try{
$process.Start() | Out-Null
$standardOut = $process.StandardOutput.ReadToEnd()
}
catch{
$standardOut = "WMI ERROR"
}
finally{
$process.WaitForExit()
Add-Content C:\script\list_of_computers_in_DOMAIN.log $b","$standardOut
}
}
There are no longer any errors that get output to the console, BUT, the output file is not as I wish.
When there is an WMI error, I would like the following line to be written
'sender-ip=10.10.10.10', WMI Error
But instead, the following is written
'sender-ip=10.10.10.10',Get-WmiObject : The RPC server is unavailable.
(Exception from HRESULT: 0x800706BA) ...many lines of error
or any other error may be printed instead of WMI Error.
Thanks once again!