Log output of ForEach loop - powershell

Question

The code below gets computer info remotely. I couldn't get it send output to a log file. Also, how do I log all unqueried computers in a separate log file?
Code:
$ArrComputers = gc .\computernames.txt
Clear-Host
ForEach ($Computer in $ArrComputers)
{
$computerSystem = get-wmiobject Win32_ComputerSystem -Computer $Computer
$computerBIOS = get-wmiobject Win32_BIOS -Computer $Computer
$Version = Get-WmiObject -Namespace "Root\CIMv2" -Query "Select * from Win32_ComputerSystemProduct" -computer $computer | select version
write-host "System Information for: " $computerSystem.Name -BackgroundColor DarkCyan
"-------------------------------------------------------"
"Model: " + $computerSystem.Model
"Serial Number: " + $computerBIOS.SerialNumber
"Version: " + $Version
""
"-------------------------------------------------------"
}

Answer 1

Logging is fairly straightforward. You just need to store output in a variable and then use Out-File cmdlet:
$ArrComputers = gc .\computernames.txt
$OutputLog = ".\output.log" # Main log
$NotRespondingLog = ".\notresponding.log" # Logging "unqueried" hosts
$ErrorActionPreference = "Stop" # Or add '-EA Stop' to Get-WmiObject queries
Clear-Host
ForEach ($Computer in $ArrComputers)
{
try
{
$computerSystem = get-wmiobject Win32_ComputerSystem -Computer $Computer
$computerBIOS = get-wmiobject Win32_BIOS -Computer $Computer
$Version = Get-WmiObject -Namespace "Root\CIMv2" `
-Query "Select * from Win32_ComputerSystemProduct" `
-computer $computer | select -ExpandProperty version
}
catch
{
$Computer | Out-File -FilePath $NotRespondingLog -Append -Encoding UTF8
continue
}
$Header = "System Information for: {0}" -f $computerSystem.Name
# Outputting and logging header.
write-host $Header -BackgroundColor DarkCyan
$Header | Out-File -FilePath $OutputLog -Append -Encoding UTF8
$Output = (#"
-------------------------------------------------------
Model: {0}
Serial Number: {1}
Version: {2}
-------------------------------------------------------
"#) -f $computerSystem.Model, $computerBIOS.SerialNumber, $Version
# Ouputting and logging WMI data
Write-Host $Output
$Output | Out-File -FilePath $OutputLog -Append -Encoding UTF8
}

Answer 2

In its current state, your code will give an error for each computer the Get-WmiObject command could not reach. I would consider using -ErrorAction SilentlyContinue -ErrorVariable Err at the end of the first Get-WmiObject command. This will stop the errors from coming to your screen and clogging your output. You can then condition the other two calls to Get-WmiObject to only happen if the ErrorVariable is empty. If it exists, log the name of the computer, and then output to a file.
The reason you are not able to log anything else to a file is because you are using Write-Host. I would consider using a PSObject to return information. This will allow you to see the output on the screen in an organized fashion while also allowing you to write output to a file.
Also, using the -ExpandProperty switch with Select-Object will keep you from returning a hashtable for the Version property.