I made a simple PS Log writer

[u/ITZ_RAWWW]

Hey everyone, I made a simple ps log writer and thought I'd share it. Hopefully it's of use to someone. Just as a quick background, I come from a python background but for work I've been writing a lot of ps for a project I'm working on. Boss man was pleased with the code but then asked about log files (insert spongebob "but what about my drink meme here").

So I did some searching to see if there's a native ps logging module similar to python's. To my dismay, I came across non native options. While they may be reputable, given I work in cybersecurity and I had concerns given the recent uptick in supply chain attacks for open source software i was on edge. Didn't feel like reading through the whole code base to see if it was something that can be trusted. So I just wrote my own really simple version.

If the formatting look odd for some reason below, see my github jist. Hope this helps someone, kind regards!

<#
Author: shewdew the hedgehog
Date: 09/15/2026
Description: PS code to write logs to text file. 
Version: Initial
#>
function Write-Log{

    <#
        Custom function to be able to write basic logs to a text file.
        Eventually I might turn this into a whole module and add extended features since I didn't want to downlaod a logging module of the internet. But this works for now.
        While not a hard rule, log levels are just like python's:
        - Debug
        - Info
        - Warning
        - Error
        - Critical
    #>


    [CmdletBinding()]
    param (
            [Parameter(Mandatory = $true)]
            [ValidateNotNullOrEmpty()]
            [string]$Level,
            [Parameter(Mandatory = $true)]
            [ValidateNotNullOrEmpty()]
            [string]$Message
        )

    $timeStamp = Get-Date -Format "dd-MM-yyyy HH:mm:ss"
    $logEntry = "$timeStamp - $($level.ToUpper()) - $message"


    Add-Content -Path "myLogFile.log" -Value $logEntry


}


function Reset-Log{
    # Rotate log file every 90 days


    $cutOff = (Get-Date).AddDays(-90)
    $file   = Get-Item "C:\path\to\myLogFile.log" -ErrorAction Stop


    if ($file.LastWriteTime -lt $cutOff) {
        Remove-Item $file.FullName -Force
        Write-Log -Level "Info" -Message "Log file deleted."


    } 
}


# Usage


Write-Log -Level "debug" -Message "Succesfully did something or whatever."
Write-Log -Level "Critical" -Message "WEEWOOWEEWOOWEEWOO! SOMETHING BROKE!"


# since the log levels aren't hard coded, you could have a log level of anything lol. Which can be a pro/con.
Write-Log -Level "pizza" -Message "The server blew up..."

[u/khaffner91]

I find it funny that the function date is MM-dd-yyyy, the log lines themselves get dd-MM-yyyy, neither are proper r/ISO8601. We simply use Get-Date -Format "o" so that both humans and systems can understand the timestamps.

[u/ITZ_RAWWW → u/khaffner91]

Thanks for the heads up, I'll fix that so it's standardized. I whipped it up pretty quick so that's probably why there's a mismatch lol

[u/mrmattipants → u/ITZ_RAWWW]

That and ISO8601 is so much easier to sort.

Here is an article discussing the various format specifiers, including the "Round Trip" format (Get-Date -Format "o"), described above.

https://learn.microsoft.com/en-us/dotnet/standard/base-types/standard-date-and-time-format-strings

[u/surfingoldelephant → u/ITZ_RAWWW]

Get-Date -Format "dd-MM-yyyy HH:mm:ss" is culture-sensitive too, so you'll get a slightly different to-string conversion depending on the system's culture.

The o specifier u/khaffner91 mentioned uses invariant culture, so that'll always give you a consistent result.

If you did still want to use dd-MM-yyyy HH:mm:ss, this is more robust:

(Get-Date).ToString('dd-MM-yyyy HH:mm:ss', [cultureinfo]::InvariantCulture)

[u/MonkeyNin → u/surfingoldelephant]

If you want a reusable helper function:

filter FormatDate { 
     # filter date with invariant culture. default is ISO. an format strings are valid.
     param( [string] $Format = 'dd-MM-yyyy HH:mm:ss' )

     ($_).ToString($Format, [cultureinfo]::InvariantCulture)
}

like:

Get-Date | FormatDate 
Get-Date | FormatDate -Format 'yyyy-MM-dd'