PowerShell Core

14 Aug 2022

PowerShell Core

PowerShell Core, introduced in 2016 is open-source and designed to run cross-platform on Windows, Mac, and Linux. PowerShell Core runs on top of .NET Core, a cross-platform, open-source version of .NET.

PowerShell and PowerShell Core can run in parallel, and its important to remember that not all cmdlets and features are available in PowerShell Core.

The following are my notes while taking part in LinkedIn Learning course Learning PowerShell Core.

Installation

Windows

Windows Installation Documentation

Download Windows (x64) LTS MSI file - at the time, version 7.2 LTS is the current stable.

The default install options are

powershell-core-1

powershell-core-2

Once installed you can verify the installed version

$PSVersionTable

To call PowerShell Core from a normal command prompt use the command

PWSH

Linux

Installation Documentation

Ubuntu Install Script

# Update the list of packages
sudo apt-get update
# Install pre-requisite packages.
sudo apt-get install -y wget apt-transport-https software-properties-common
# Download the Microsoft repository GPG keys
wget -q "https://packages.microsoft.com/config/ubuntu/$(lsb_release -rs)/packages-microsoft-prod.deb"
# Register the Microsoft repository GPG keys
sudo dpkg -i packages-microsoft-prod.deb
# Update the list of packages after we added packages.microsoft.com
sudo apt-get update
# Install PowerShell
sudo apt-get install -y powershell

Debian 11 Install Script

# Install system components
sudo apt update  && sudo apt install -y curl gnupg apt-transport-https

# Import the public repository GPG keys
curl https://packages.microsoft.com/keys/microsoft.asc | sudo apt-key add -

# Register the Microsoft Product feed
sudo sh -c 'echo "deb [arch=amd64] https://packages.microsoft.com/repos/microsoft-debian-bullseye-prod bullseye main" > /etc/apt/sources.list.d/microsoft.list'

# Install PowerShell
sudo apt update && sudo apt install -y powershell

Run and Verify

PWSH

$PSVersionTable

powershell-core-3

Help

To access help by using the command below or help.

Get-Help

To update your offline help files, use the update command.

Update-Help

Use the online help, through a browser

Get-Help -Name Get-Cotent -Online

Help has different levels of detail, starting from the basic to full.

Get-Help -Name Get-Cotent

Get-Help -Name Get-Cotent -Detailed

Get-Help -Name Get-Cotent -Full

Get-Help -Name Get-Cotent -Examples

Commands

The help documentation is always a good place to start when learning what a command does.

Get-Help Get-Command

List all commands available

Get-Command

Get all commands that start with the verb “Get”.

Get-Command -Verb Get

powershell-core-4

Get all commands that contain the noun “Module”, this can also be wrapped with wildcards to provide more results.

Get-Command -Noun Module

powershell-core-5

Get commands with a specific parameter, such as “ComputerName”.

Get-Command -ParameterName ComputerName

powershell-core-6

Get all the commands contained within a specific module, in the example below I use the “PackageManagement” module.

Get-Command -Module PackageManagement

powershell-core-7

Alias

To list all configured alias, use the following command;

Get-Alias

If you wanted to know a specific alias, just append that to the end

Get-Alias -Name cls

powershell-core-8

Pipeline

The pipeline allows the administrator to stitch one command to another, passing the object through, for example.

Get-Service -Name "BITS" | Start-Service

Objects

  • Methods = Actions that an object can take.
  • Properties = An attribute of an object.

To see all the available methods and properties on an object, use Get-Member.

Get-Date | Get-Member

powershell-core-9

PowerShell hides some properties, these can all be shown by using the Select-Object command.

Get-Date | Select-Object *

powershell-core-10

Modules

To find all the currently imported modules

Get-Module

The above command does not show all available modules, to list all available modules use the following command:

Get-Module -ListAvailable

powershell-core-11

To list the available commands within a module use:

Get-Command -Module PackageManagement

powershell-core-12

If you wish to remove a module from current PowerShell session, you can use the command:

Remove-Module -Name PackageManagement

Modules are stored in the Module Path

$env:PSModulePath

To import a module

Import-Module -Name PackageManagement

To import a module from a different location

Import-Module -Name /home/user/Downloads/module

Additional modules can be found on PowerShell Gallery, the web interface is easy to use.

To find modules via PowerShell use

Find-Module

Most modules are designed for Windows PowerShell, but we can filter by tag for PowerShell Core

Find-Module -Tag 'PSEdition_Core'

To install a module either use a pipe or install command

Find-Module -Name AdminToolbox.ActiveDirectory | Install-Module

Install-Module -Name AdminToolbox.ActiveDirectory

powershell-core-13

Its important to keep modules up-to-date, review your versions

Get-Module -Name AdminToolbox.Remoting -ListAvailable

Find-Module -Name AdminToolbox.Remoting

Update by using the command

Update-Module -Name AdminToolbox.Remoting

To uninstall a module completely

Uninstall-Module -Name AdminToolbox.ActiveDirectory

Functions

Are blocks of code that can be reused, if you PowerShell scripts contain repeated code, this is a good opportunity to utilise a function.

Functions should be defined before they are needed, at the top of the script.

When naming a function always try to use the PowerShell verb noun convention.

Parameters provide the mechanism that allows a cmdlet to accept input

function Test-ServiceStarted {
    param(
        [Parameter()]
        [string]$Name
    )
    
    if ((Get-Service -Name $Name).Status -eq 'Running'){
        $True
    } else {
        $False
    }

}

Test-ServiceStarted -Name  wuauserv

Remote Resource Management

Any Windows Server after 2012 R2 will have PSRemoting enabled by default, but there are additional configuration required such as; Firewall exeception and the Service running.

To enable use the command

Enable-PSRemoting

Create a PowerShell Temporary session

$credential = Get-Credential

Invoke-Command -ComputerName 192.168.100.169 -Credential $credential -ScriptBlock { hostname }

Create a PowerShell session

$credential = Get-Credential

Enter-PSSession -ComputerName 192.168.100.169 -Credential $credential

Remoting from Linux to Windows

SSH is used to connect to and from Linux systems.

  1. Install OpenSSH for Windows
  2. Configure Remoting SSH on Windows

Install OpenSSH server

Get-WindowsCapability -Online | Where-Object Name -Like 'OpenSSH.Server' | Add-WindowsCapability -Online

Configure service

Start-Service sshd

Set-Service -Name sshd -StartupType 'Automatic'

Edit file C:\ProgramData\ssh\sshd_config, adding the following Subsystem

Subsystem powershell c:/progra~1/powershell/7/pwsh.exe -sshs -NoLogo

Ensure PasswordAuthentication is configured to yes.

Restart the sshd service

Restart-Service sshd
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