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Resource Cheatsheet

PowerShell: Adding Commands

MoL ch. 7 — management shells, snap-ins vs modules, module discovery/import, profile scripts, and the PowerShell Gallery.

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Ch. 7
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Drafted from general knowledge: the source was the chapter’s heading list with an instruction to draft from general knowledge, not a transcript — verify against your own copy of Jones & Hicks’s book for their specific wording/examples.

In one line: PowerShell gains product-specific commands via extensions — legacy snap-ins or modern (auto-loading, cross-platform) modules — with -Prefix resolving naming conflicts, $PROFILE preloading them at startup, and the PowerShell Gallery as the install source.

Companion to: Learn Windows PowerShell in a Month of Lunches (3rd ed.), Don Jones & Jeffery Hicks, Chapter 7. The full version is the Adding Commands class notes; the chapter overview is the Learn PowerShell resource sheet.

The core idea

  • “Management shells” (Exchange, SQL Server, etc.) are just ordinary PowerShell with one extension preloaded by their shortcut — not a separate engine.

Snap-ins vs modules

Snap-in (legacy) Module (modern)
List Get-PSSnapin -Registered Get-Module -ListAvailable
Load Add-PSSnapin <name> Import-Module <name>
Currently loaded Get-PSSnapin Get-Module
Cross-platform (PS 7/Core)? No Yes (mostly)
Auto-loads? No Yes, since PS 3.0

Command conflicts

  • Same-named command from two modules → most recently imported wins.
  • Avoid deliberately: Import-Module ModuleB -Prefix B → Get-Status and Get-BStatus coexist.
  • Unload: Remove-Module <name>.

Playing with a new module

Get-Module -ListAvailable NewModuleName
Import-Module NewModuleName
Get-Command -Module NewModuleName
Get-Help <SomeNewCommand> -Examples

Profile scripts

$PROFILE             # path to your personal (current user/host) profile
Test-Path $PROFILE   # does it exist yet?

Add Import-Module X lines there to preload extensions every session. $PROFILE is one of several profile scopes (user/host combinations).

Getting modules from the internet

Find-Module -Name SomeModule
Install-Module -Name SomeModule
Install-Module -Name SomeModule -Scope CurrentUser   # no admin needed

Common points of confusion

  • Installed (on disk, Get-Module -ListAvailable) ≠ imported (loaded now, Get-Module).
  • Snap-in ≠ module — different commands, different platform support.
  • Install-Module without -Scope CurrentUser → all users, needs admin.
  • A “management shell” is not special — it’s PowerShell + a preloaded extension.

🔐 Security notes

  • A module is code, not data — install only from trusted sources (official Gallery listing, known publisher).
  • PowerShell Gallery is an open registry — same supply-chain risk as any package registry; check publisher/reputation before installing into anything that matters.
  • -Scope CurrentUser narrows blast radius, not just admin friction — a bad module affects one profile, not every user.
  • Profile scripts are a persistence favourite — they run automatically every startup; a rogue line in $PROFILE runs silently forever. Review it periodically and protect write access.
  • Execution policy is a related control (not in this chapter) restricting which scripts run at all — an overly permissive policy removes a speed bump against unwanted code.

Practice drills

1. What is a "management shell" really?

Ordinary PowerShell with one particular extension already loaded by the shortcut that launches it.

2. Commands to list and load a snap-in?

Get-PSSnapin -Registered (list); Add-PSSnapin (load).

3. What happens since PowerShell 3.0 when you type a command from an installed-but-not-imported module?

PowerShell auto-discovers and auto-loads the module that provides it, no explicit Import-Module needed.

4. Two modules both define Get-Status. How do you use both?

Import one normally, the other with -Prefix (e.g. Import-Module ModuleB -Prefix B), giving Get-Status and Get-BStatus.

5. Which extension type doesn't work outside Windows PowerShell?

Snap-ins — they don’t work in PowerShell 7/Core.

6. What does $PROFILE do, and why edit it?

Points to your personal profile script; edit it to preload modules/settings automatically at startup.

7. What does -Scope CurrentUser change on Install-Module?

Installs for the current user only, avoiding the need for administrator rights.

Key takeaways

  • “Management shells” = PowerShell + a preloaded extension, nothing more exotic.
  • Modules superseded snap-ins: cross-platform, auto-loading, the modern standard.
  • -Prefix resolves naming conflicts; Remove-Module unloads.
  • $PROFILE preloads extensions at startup; PowerShell Gallery (Find-Module/Install-Module) is the install source.
  • Security: modules are code — trust the source, prefer -Scope CurrentUser, and watch profile scripts as a persistence spot.

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