Chapter 7: Adding commands
Introduces PowerShell’s extensibility through its growing set of commands for Azure products.
After this chapter you will be able to
- PowerShell command extensibility. Explain that PowerShell can gain commands for more products as Microsoft develops them, including Azure services typically managed through the Azure portal.
- Modules as command extensions. Explain that PowerShell can gain commands through extensions called modules, much as a smartphone app can add a voice-assistant command without an operating-system upgrade.
- Repository discovery and management. Describe how PowerShellGet works with repositories: Register-PSRepository adds one, Find-Module searches for modules, Install-Module installs one, and Update-Module gets a newer version. Explain how the Gallery's module page helps check PowerShell Core testing and installation requirements.
- Installation and availability check. Describe the Az example: run Install-Module -Name Az, respond to the Gallery trust prompt, and use Get-Module -ListAvailable to verify installation because the module is not yet loaded.
- Module search paths. Explain that PSModulePath lists the locations where PowerShell looks for modules, including locations for system, shared, and personal modules. Describe what to do when a module is elsewhere.
- Module autodiscovery and autoloading. Describe how PowerShell can discover commands, offer completion and help, and load a module when its command is run without the user first loading that module.
- Product-specific command prefixes. Explain why most PowerShell extensions add a short prefix to the noun in their command names, as in Get-GcSqlInstance or Get-AzStorageTable.
- Exploring an unfamiliar module. Describe how the authors use help to find a command for making a zip archive, then load its module and list the other available commands. Explain why they load the module manually even though PowerShell could load it automatically.
- Creating a zip archive. Describe what the authors check before trying Compress-Archive and how they test it on a file.
- Finding help for module commands. Explain how to find a relevant command in a large module and learn to use it: narrow the list with Help or Get-Command and wildcards, then read the command’s help with -Example or -Full.
What it builds on
- Using help to find commands (chapter 3) · Finding commands with PowerShell’s help system.
- Optional and mandatory parameters (chapter 3) · Recognizing mandatory parameters in command help.
- Finding command examples (chapter 3) · Finding command examples in help.
Section by section
Introduction
Introduces PowerShell’s extensibility through its growing set of commands for Azure products.
- PowerShell command extensibility: Explain that PowerShell can gain commands for more products as Microsoft develops them, including Azure services typically managed through the Azure portal.
Why it matters: PowerShell’s commands are not limited to a fixed set of products.
Key terms: extensibility, commands, Azure portal
7.1 How one shell can do everything
This section explains how PowerShell can gain new commands through modules, using smartphone apps as an analogy.
- Modules as command extensions: Explain that PowerShell can gain commands through extensions called modules, much as a smartphone app can add a voice-assistant command without an operating-system upgrade.
Why it matters: This gives you a way to think about where additional PowerShell commands come from.
Key terms: modules, commands, extensions
7.2 Extensions: Finding and installing modules
This section explains what PowerShell modules are and how to find, install, update, and verify modules from online repositories.
- PowerShell module extensions: Explain that PowerShell v6 and newer use modules as their extension type, and that modules are designed to be self-contained and easier to distribute.
Why it matters: It clarifies what kind of extension you are looking for when adding commands. - Repository discovery and management: Describe how PowerShellGet works with repositories: Register-PSRepository adds one, Find-Module searches for modules, Install-Module installs one, and Update-Module gets a newer version. Explain how the Gallery's module page helps check PowerShell Core testing and installation requirements.
Why it matters: These are the starting points for finding a suitable module and keeping it current. - Installation and availability check: Describe the Az example: run Install-Module -Name Az, respond to the Gallery trust prompt, and use Get-Module -ListAvailable to verify installation because the module is not yet loaded.
Why it matters: The availability check lets you confirm installation without mistaking an unloaded module for a missing one. - Gallery code caution: Explain why a module appearing in the Microsoft-run PowerShell Gallery should not be treated as Microsoft-verified or endorsed.
Why it matters: A familiar repository name is not a guarantee that its contributed code is safe to run.
Key terms: module, snap-in, PowerShellGet, PowerShell Gallery, Register-PSRepository, Find-Module, Install-Module, Update-Module, Install-Module -Name Az, Get-Module
7.3 Extensions: Finding and adding modules
This section explains how PowerShell finds modules through PSModulePath, makes their commands available automatically, and handles modules outside those paths.
- Module search paths: Explain that PSModulePath lists the locations where PowerShell looks for modules, including locations for system, shared, and personal modules. Describe what to do when a module is elsewhere.
Why it matters: A module’s location determines whether PowerShell can find it automatically. - Module autodiscovery and autoloading: Describe how PowerShell can discover commands, offer completion and help, and load a module when its command is run without the user first loading that module.
Why it matters: You can find and try installed commands without manually importing every module first. - Google Cloud module exception: Describe why the GoogleCloud module needs an explicit import after installation and what that import triggers.
Why it matters: This example shows that a module requiring first-use input may not follow the usual autodiscovery experience.
Key terms: PSModulePath, Import-Module, system modules, shared, personal modules, autodiscovery, autoloading, Tab, IntelliSense, Update-Help
7.4 Command conflicts and removing extensions
This section explains how command prefixes prevent module naming conflicts and how to access or remove commands when conflicts occur.
- Product-specific command prefixes: Explain why most PowerShell extensions add a short prefix to the noun in their command names, as in Get-GcSqlInstance or Get-AzStorageTable.
Why it matters: Prefixes help you recognize which extension a command belongs to and avoid name collisions. - Same-name command resolution: Describe what happens when two loaded modules contain a command with the same name and how to call the other command specifically.
Why it matters: A naming conflict does not make the earlier command unavailable. - Module conflict remedies: Describe how to unload a conflicting module and how to supply a prefix when importing one.
Why it matters: You can address a conflict either by unloading a module or by giving imported commands distinct names.
Key terms: prefix, noun, command conflicts, module name, command name, Get-User, Remove-Module, Import-Module, -Prefix
7.5 Playing with a new module
The section demonstrates how to explore an unfamiliar PowerShell module and use its Compress-Archive command to create a zip file.
- Exploring an unfamiliar module: Describe how the authors use help to find a command for making a zip archive, then load its module and list the other available commands. Explain why they load the module manually even though PowerShell could load it automatically.
Why it matters: This gives you a way to teach yourself about commands for a new task. - Creating a zip archive: Describe what the authors check before trying Compress-Archive and how they test it on a file.
Why it matters: Checking required parameters lets you try a newly discovered command without guessing its inputs. - Verbose output and overwriting: Explain why the authors retry the command with -Verbose and -Force, including what each switch does in this example.
Why it matters: These switches make the retry informative and allow it to replace the archive from the first run.
Key terms: help system, Microsoft.PowerShell.Archive, module, Compress-Archive, -Path, -DestinationPath, mandatory parameters, -Verbose, -Force
7.6 Common points of confusion
This section explains how to avoid getting lost among module commands by narrowing the command list and reading detailed help, especially examples.
- Finding help for module commands: Explain how to find a relevant command in a large module and learn to use it: narrow the list with Help or Get-Command and wildcards, then read the command’s help with -Example or -Full.
Why it matters: This approach makes a large set of new module commands manageable and helps you use the command you find.
Key terms: modules, Help, Get-Command, wildcards, -Example, -Full
7.7 Lab
7.8 Lab answers
Where this is used later
- Finding the commands (chapter 9) · Finding and installing modules.
- Working with Azure PowerShell (chapter 10) · Installing a PowerShell module
- Ideas for further exploration (chapter 27) · Finding and installing PowerShell modules
- Learning to use the commands (chapter 9) · Learning to use the commands relies on reading their help.
Concepts explained in this chapter
- Install-ModuleInstall-Module is a PowerShell cmdlet that downloads and installs PowerShell modules from a package repository.
- Import-ModuleImport-Module is a PowerShell cmdlet that loads a module into the current session from a module name or path.
- moduleA module is a packaged unit of reusable code and related resources that can be loaded into a software environment.
- PowerShell GalleryPowerShell Gallery is an online repository for discovering and distributing PowerShell modules, scripts, and related packages.
- Get-CommandGet-Command is a PowerShell cmdlet that retrieves commands matching specified names, verbs, nouns, or command types.
- Get-HelpHelp is a PowerShell command that displays help content for commands and other PowerShell elements.
- full helpFull help is the detailed help view for a PowerShell command, including comprehensive parameter descriptions and metadata.
- wildcardA wildcard is a pattern-matching character or expression that represents one or more possible characters in a name or search.
- Get-ModuleGet-Module is a PowerShell cmdlet that lists or retrieves information about modules available in or loaded into a session.
- -expandproperty-ExpandProperty is a Select-Object parameter that outputs the values of a specified property instead of objects containing that property.
- commandA command is an executable instruction that a shell can invoke to perform an operation.
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