Guides on Martin Olsson

Configure PowerShell

Thu, 09 Apr 2026 13:55:49 +0200

Repositories Link to heading

Add a custom repository.

Register-PSRepository -Name 'MyCustomRepository' -SourceLocation 'path\to\custom\repository' -ScriptSourceLocation 'path\to\custom\repository' -InstallationPolicy Trusted

Modules Link to heading

Uninstall all versions except the latest for an installed module.

$moduleName = 'InsertNameOfTheModule'
Get-InstalledModule -Name $moduleName | ForEach-Object {
    $latestInstalledVersion = $_.Version
    Get-InstalledModule -Name $_.Name -AllVersion | Where-Object { $_.Version -ne $latestInstalledVersion } | Uninstall-Module -Verbose
}

Scripts Link to heading

Uninstall all versions except the latest for an installed script.

Use Git and GitHub

Thu, 09 Apr 2026 07:45:16 +0200

A collection of commands for reference Link to heading

Configure git.

git config --global user.name "<name>"
git config --global user.email <email>

git config --list

Clone a repository to the local machine.

git clone https://github.com/MyUsername/MyRepository.git

Add GitHub remote management to the repository.

git remote add origin https://github.com/MyUsername/MyRepository.git

Show remote repositories.

git remote -v

Automatically run PowerShell scripts on Windows startup

Tue, 26 Aug 2025 06:55:57 +0200

Configure Windows Task Scheduler to automatically run a script on logon Link to heading

Create the script Link to heading

This is a sample PowerShell script for backing up files (Copy-BackupFiles.ps1).

function Copy-BackupFile {
    param(
        [Parameter(Mandatory, ValueFromPipeline, ValueFromPipelineByPropertyName)]
        [ValidateNotNull()]
        [string]$Path,

        [Parameter(Mandatory)]
        [ValidateNotNullOrEmpty()]
        [string[]]$Destination,

        [string]$Filter = '*.*',

        [int]$RetryCount = 2,

        [int]$RetryWaitSeconds = 5,

        [switch]$PurgeDestinationFiles
    )

    foreach ($sourcePath in $Path) {
        if (Test-Path -Path $sourcePath -PathType Container) {
            $sourceFiles = Get-ChildItem -Path $sourcePath -File -Recurse

            if (($sourceFiles | Measure-Object).Count -gt 0) {
                foreach ($destPath in $Destination) {
                    if (Test-Path -Path (Split-Path -Path $destPath -Parent) -PathType Container) {
                        try {
                            Write-Verbose "$($sourcePath) --> $($destPath)"
                            if ($PurgeDestinationFiles) {
                                robocopy $sourcePath $destPath $Filter /PURGE /S /R:$RetryCount /W:$RetryWaitSeconds
                            }
                            else {
                                robocopy $sourcePath $destPath $Filter /S /R:$RetryCount /W:$RetryWaitSeconds
                            }
                        }
                        catch {
                            Write-Error ('Failed to copy files from "{0}" to "{1}". {2}' -f $sourcePath, $destPath, $PSItem)
                        }
                    }
                    else {
                        Write-Error ('Cannot find the parent directory of destination path "{0}".' -f $destPath)
                    }
                }
            }
            else {
                Write-Error ('No files in "{0}".' -f $Path)
            }
        }
        else {
            Write-Error ('Cannot find the source path "{0}".' -f $sourcePath)
        }
    }
}

$params = @{
    Path = "$env:USERPROFILE\Documents\MyFolder"
    Destination = @(
        '\\NAS\home\Backup\MyFolder'
        "$env:USERPROFILE\OneDrive - FirstName LastName\Backup\MyFolder"
    )
    PurgeDestinationFiles = $true
}
Copy-BackupFile @params

Create the scheduled task Link to heading

Open Task Scheduler and create a new task. Configure the following settings.

Connect to a Linux host using SSH key instead of credentials

Wed, 20 Aug 2025 06:46:54 +0200

Generate a new SSH key on the client Link to heading

ssh-keygen -t rsa -b 4096

Copy the public key to the host/server Link to heading

Method 1: Automatically copy the key to the host Link to heading

Command alternative 1:

cat ~/.ssh/id_rsa.pub | ssh user@host 'cat >> ~/.ssh/authorized_keys'

Command alternative 2:

ssh user@host 'cat >> ~/.ssh/authorized_keys' < ~/.ssh/id_rsa.pub

Method 2: Manually copy the key Link to heading

On the client: View the public key to be able to copy it.

Manage secrets with PowerShell

Sun, 10 Aug 2025 13:40:57 +0200

Set up a new secret store Link to heading

Install required modules.

Install-Module Microsoft.PowerShell.SecretManagement, Microsoft.PowerShell.SecretStore

Export your vault password to a CLI XML file in your PowerShell profile directory.

$vaultPassword = Read-Host 'Enter a vault password' -AsSecureString
$vaultPasswordPath = Join-Path -Path (Split-Path -Path $PROFILE) -ChildPath 'SecretStore.vault.credential'
$vaultPassword | Export-CliXml -Path $vaultPasswordPath

Set-SecretStoreConfiguration -Scope CurrentUser -Authentication Password -PasswordTimeout (60 * 60) -Interaction None -Password $vaultPassword -Confirm:$false
Register-SecretVault -Name 'SecretStore' -ModuleName Microsoft.PowerShell.SecretStore -DefaultVault

Add a secret to the vault Link to heading

Unlock the vault.

Generate a Let's Encrypt certificate with PowerShell

Sun, 10 Aug 2025 13:40:43 +0200

This method will allow you to automate Let’s Encrypt certificate creation/renewal with PowerShell.

Install the Posh-ACME module.

Install-Module Posh-ACME

Create a new certificate Link to heading

Set the Let’s Encrypt server to staging, to make sure everything works before changing it to the production server.

This will produce certificate files, but they will not be valid for production use. Changing it to LE_PROD will allow you to create a valid certificate (see steps further down in the guide).

Automatically backup files from Linux to an SFTP server

Sun, 10 Aug 2025 13:40:11 +0200

Prepare authentication to the SFTP server Link to heading

Generate an SSH key on the client Link to heading

This will allow the client to authenticate to the server without a username and password.

Generate the SSH key.

ssh-keygen -t rsa -b 4096

Copy the SSH key.

cat ~/.ssh/id_rsa.pub

Add the SSH key to the SFTP server Link to heading

Open the authorized keys file and add the SSH key on a new line.

Send automated email with PowerShell and Microsoft Graph

Thu, 07 Aug 2025 13:08:39 +0200

Use this method to securely automate the sending of email from your PowerShell scripts, by authenticating to MS Graph with a certificate (instead of username and password) through a custom Entra app.

Create a mail-enabled security group Link to heading

This will limit which mailbox(es) can send automated email from the Entra app. It’s technically not required, but recommended for security and privacy reasons.

The group will only be used to control which mailboxes will be allowed to send mail through the Entra app. The group’s mail address will not be used for anything.