The other day I posted a quick primer on logging in our PS scripts. Here I will expand on that, with a use-case example I just wrote code for yesterday. Here is a registry-reading function I bashed together, as but one example of something I needed to accomplish in reading in a setting and logging it. Thus allowing me to keep a thorough, auditable record of registry changes during an automation task.

Reading Registry Values and Logging Them

For many automation tasks, you’ll need to retrieve configurations from the Windows Registry. The Get-RegistryValue function allows you to read a specific property from the Registry without cluttering your code. Errors are cleanly handled (returning $false if a value can’t be found), making it easy to integrate error-checking and logging.

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Function Get-RegistryValue($RegPath, $Property) {
    Try {
        $Item = Get-ItemProperty -Path $RegPath -Name $Property -ErrorAction Stop
        $ItemProperty = $Item | Select -ExpandProperty $Property
        Return $ItemProperty
    }
    Catch {
        Return $false
    }
}

And here’s a recap of the Writelog function I wrote about the other day:

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Function WriteLog($LogString) {
    ##########################################################################
    ## Writes a timestamped entry to a log file defined by $LogFile variable
    ##########################################################################

    $Stamp = (Get-Date).ToString("yyyy/MM/dd HH:mm:ss")
    $LogMessage = "$Stamp $LogString"
    Add-Content $LogFile -Value $LogMessage
}

Example Usage:

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$SomeValue = Get-RegistryValue 'HKLM:\SOFTWARE\MyApp' 'InstallPath'

If ($SomeValue) {
    WriteLog "Successfully retrieved InstallPath value: $SomeValue"
} Else {
    WriteLog "Failed to retrieve InstallPath from registry."
}

You should log everything you’re reading-in, or changes you’re making (files written, etc) during any scheduled or automated run of your PS scripts. This example shows a combination of Get-RegistryValue and WriteLog function to demonstrate a use-case, and the benefit becomes obvious once you make this a coding practice: you can retrieve configurations, make decisions based on those values, and log both the successes and failures in a neatly timestamped manner.

Happy scripting…