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About Modules

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Short Description

Explains how to install, import, and use PowerShell modules.

Long Description

A module is a package that contains PowerShell commands, such as cmdlets, providers, functions, workflows, variables, and aliases.

People who write commands can use modules to organize their commands and share them with others. People who receive modules can add the commands in the modules to their PowerShell sessions and use them just like the built-in commands.

This topic explains how to use PowerShell modules. For information about how to write PowerShell modules, see Writing a PowerShell Module.

What Is a Module?

A module is a package of commands. All cmdlets and providers in your session are added by a module or a snap-in.

Module Auto-Loading

Beginning in PowerShell 3.0, PowerShell imports modules automatically the first time that you run any command in an installed module. You can now use the commands in a module without any set-up or profile configuration, so there's no need to manage modules after you install them on your computer.

The commands in a module are also easier to find. The Get-Command cmdlet now gets all commands in all installed modules, even if they are not yet in the session, so you can find a command and use it without importing.

Each of the following examples cause the module containing Get-Mailbox to be imported into your session.

  • Run the Command

    Get-Mailbox -Identity Chris

  • Get the Command

    Get-Command Get-Mailbox

  • Get Help for the Command

    Get-Help Get-Mailbox

Get-Command commands that include a wildcard character (*) are considered to be for discovery, not use, and do not import any modules.

Only modules that are stored in the location specified by the PSModulePath environment variable are automatically imported. Modules in other locations must be imported by running the Import-Module cmdlet.

Also, commands that use PowerShell providers do not automatically import a module. For example, if you use a command that requires the WSMan: drive, such as the Get-PSSessionConfiguration cmdlet, you might need to run the Import-Module cmdlet to import the Microsoft.WSMan.Management module that includes the WSMan: drive.

You can still run the Import-Module command to import a module and use the $PSModuleAutoloadingPreference variable to enable, disable and configure automatic importing of modules. For more information, see about_Preference_Variables.

How to Use a Module

To use a module, perform the following tasks:

  1. Install the module. (This is often done for you.)
  2. Find the commands that the module added.
  3. Use the commands that the module added.

This topic explains how to perform these tasks. It also includes other useful information about managing modules.

How to Install a Module

If you receive a module as a folder with files in it, you need to install it on your computer before you can use it in PowerShell.

Most modules are installed for you. PowerShell comes with several preinstalled modules, sometimes called the "core" modules. On Windows-based computers, if features that are included with the operating system have cmdlets to manage them, those modules are preinstalled. When you install a Windows feature, by using, for example, the Add Roles and Features Wizard in Server Manager, or the Turn Windows features on or off dialog box in Control Panel, any PowerShell modules that are part of the feature are installed. Many other modules come in an installer or Setup program that installs the module.

Use the following command to create a Modules directory for the current user:

New-Item -Type Directory -Path $HOME\Documents\WindowsPowerShell\Modules

Copy the entire module folder into the Modules directory. You can use any method to copy the folder, including Windows Explorer and Cmd.exe, as well as PowerShell. In PowerShell use the Copy-Item cmdlet. For example, to copy the MyModule folder from C:\ps-test\MyModule to the Modules directory, type:

Copy-Item -Path C:\ps-test\MyModule -Destination `
    $HOME\Documents\WindowsPowerShell\Modules

You can install a module in any location, but installing your modules in a default module location makes them easier to manage. For more information about the default module locations, see the Module and DSC Resource Locations, and PSModulePath section.

How to Find Installed Modules

To find modules that are installed in a default module location, but not yet imported into your session, type:

Get-Module -ListAvailable

To find the modules that have already been imported into your session, at the PowerShell prompt, type:

Get-Module

For more information about the Get-Module cmdlet, see Get-Module.

How to Find the Commands in a Module

Use the Get-Command cmdlet to find all available commands. You can use the parameters of the Get-Command cmdlet to filter commands such as by module, name, and noun.

To find all commands in a module, type:

Get-Command -Module <module-name>

For example, to find the commands in the BitsTransfer module, type:

Get-Command -Module BitsTransfer

For more information about the Get-Command cmdlet, see Get-Command.

How to Get Help for the Commands in a Module

If the module contains Help files for the commands that it exports, the Get-Help cmdlet will display the Help topics. Use the same Get-Help command format that you would use to get help for any command in PowerShell.

Beginning in PowerShell 3.0, you can download Help files for a module and download updates to the Help files so they are never obsolete.

To get help for a commands in a module, type:

Get-Help <command-name>

To get help online for command in a module, type:

Get-Help <command-name> -Online

To download and install the help files for the commands in a module, type:

Update-Help -Module <module-name>

For more information, see Get-Help and Update-Help.

How to Import a Module

You might have to import a module or import a module file. Importing is required when a module is not installed in the locations specified by the PSModulePath environment variable, $env:PSModulePath, or the module consists of file, such as a .dll or .psm1 file, instead of typical module that is delivered as a folder.

You might also choose to import a module so that you can use the parameters of the Import-Module command, such as the Prefix parameter, which adds a distinctive prefix to the noun names of all imported commands, or the NoClobber parameter, which prevents the module from adding commands that would hide or replace existing commands in the session.

To import modules, use the Import-Module cmdlet.

To import modules in a PSModulePath location into the current session, use the following command format.

Import-Module <module-name>

For example, the following command imports the BitsTransfer module into the current session.

Import-Module BitsTransfer

To import a module that is not in a default module location, use the fully qualified path to the module folder in the command.

For example, to add the TestCmdlets module in the C:\ps-test directory to your session, type:

Import-Module C:\ps-test\TestCmdlets

To import a module file that is not contained in a module folder, use the fully qualified path to the module file in the command.

For example, to add the TestCmdlets.dll module in the C:\ps-test directory to your session, type:

Import-Module C:\ps-test\TestCmdlets.dll

For more information about adding modules to your session, see Import-Module.

How to Import a Module into Every Session

The Import-Module command imports modules into your current PowerShell session. To import a module into every PowerShell session that you start, add the Import-Module command to your PowerShell profile.

For more information about profiles, see about_Profiles.

How to Remove a Module

When you remove a module, the commands that the module added are deleted from the session.

To remove a module from your session, use the following command format.

Remove-Module <module-name>

For example, the following command removes the BitsTransfer module from the current session.

Remove-Module BitsTransfer

Removing a module reverses the operation of importing a module. Removing a module does not uninstall the module. For more information, see Remove-Module.

Module and DSC Resource Locations, and PSModulePath

The following are default locations for PowerShell modules. Starting in PowerShell 4.0, with the introduction of DSC, a new default module and DSC resource folder was introduced. For more information about DSC, see about_DesiredStateConfiguration.

  • System: $PSHOME\Modules or ($env:windir\System32\WindowsPowerShell\v1.0\Modules) System modules are those that ship with Windows and PowerShell.

    Starting in PowerShell 4.0, when PowerShell Desired State Configuration (DSC) was introduced, DSC resources that are included with PowerShell are also stored in $PSHOME\Modules, in the $PSHOME\Modules\PSDesiredStateConfiguration\DSCResources folder.

  • Current user: $HOME\Documents\WindowsPowerShell\Modules ($env:UserProfile\Documents\WindowsPowerShell\Modules)

    or

    $HOME\My Documents\WindowsPowerShell\Modules ($env:UserProfile\My Documents\WindowsPowerShell\Modules)

    This is the location for user-added modules prior to PowerShell 4.0.

In PowerShell 4.0 and later releases of PowerShell, user-added modules and DSC resources are stored in C:\Program Files\WindowsPowerShell\Modules. Modules and DSC resources in this location are accessible by all users of the computer. This change was required because the DSC engine runs as local system, and could not access user-specific paths, such as $home\Documents\WindowsPowerShell\Modules.

Starting in PowerShell 5.0, with the addition of the PowerShellGet module, and the PowerShell Gallery of community and Microsoft-created resources, the Install-Module command installs modules and DSC resources to C:\Program Files\WindowsPowerShell\Modules by default.

Note: To add or change files in the $env:Windir\System32 directory, start PowerShell with the "Run as administrator" option.

You can change the default module locations on your system by changing the value of the PSModulePath environment variable, $Env:PSModulePath. The PSModulePath environment variable is modeled on the Path environment variable and has the same format.

To view the default module locations, type:

$Env:PSModulePath

To add a default module location, use the following command format.

$Env:PSModulePath = $Env:PSModulePath + ";<path>"

The semi-colon (;) in the command separates the new path from the path that precedes it in the list.

For example, to add the C:\ps-test\Modules directory, type:

$Env:PSModulePath + ";C:\ps-test\Modules"

When you add a path to PSModulePath, Get-Module and Import-Module commands include modules in that path.

The value that you set affects only the current session. To make the change persistent, add the command to your PowerShell profile or use System in Control Panel to change the value of the PSModulePath environment variable in the registry.

Also, to make the change persistent, you can also use the SetEnvironmentVariable method of the System.Environment class to add a Path to the PSModulePath environment variable.

For more information about the PSModulePath variable, see about_Environment_Variables.

Modules and Name Conflicts

Name conflicts occur when more than one command in the session has the same name. Importing a module causes a name conflict when commands in the module have the same names as commands or items in the session.

Name conflicts can result in commands being hidden or replaced.

Hidden

A command is hidden when it is not the command that runs when you type the command name, but you can run it by using another method, such as by qualifying the command name with the name of the module or snap-in in which it originated.

Replaced

A command is replaced when you cannot run it because it has been overwritten by a command with the same name. Even when you remove the module that caused the conflict, you cannot run a replaced command unless you restart the session.

Import-Module might add commands that hide and replace commands in the current session. Also, commands in your session can hide commands that the module added.

To detect name conflicts, use the All parameter of the Get-Command cmdlet. Beginning in PowerShell 3.0, Get-Command gets only that commands that run when you type the command name. The All parameter gets all commands with the specific name in the session.

To prevent name conflicts, use the NoClobber or Prefix parameters of the Import-Module cmdlet. The Prefix parameter adds a prefix to the names of imported commands so that they are unique in the session. The NoClobber parameter does not import any commands that would hide or replace existing commands in the session.

You can also use the Alias, Cmdlet, Function, and Variable parameters of Import-Module to select only the commands that you want to import, and you can exclude commands that cause name conflicts in your session.

Module authors can prevent name conflicts by using the DefaultCommandPrefix property of the module manifest to add a default prefix to all command names. The value of the Prefix parameter takes precedence over the value of DefaultCommandPrefix.

Even if a command is hidden, you can run it by qualifying the command name with the name of the module or snap-in in which it originated.

The PowerShell command precedence rules determine which command runs when the session includes commands with the same name.

For example, when a session includes a function and a cmdlet with the same name, PowerShell runs the function by default. When the session includes commands of the same type with the same name, such as two cmdlets with the same name, by default, it runs the most recently added command.

For more information, including an explanation of the precedence rules and instructions for running hidden commands, see about_Command_Precedence.

Modules and Snap-ins

You can add commands to your session from modules and snap-ins. Modules can add all types of commands, including cmdlets, providers, and functions, and items, such as variables, aliases, and PowerShell drives. Snap-ins can add only cmdlets and providers.

Before removing a module or snap-in from your session, use the following commands to determine which commands will be removed.

To find the source of a cmdlet in your session, use the following command format:

Get-Command <cmdlet-name> | Format-List -Property verb,noun,pssnapin,module

For example, to find the source of the Get-Date cmdlet, type:

Get-Command Get-Date | Format-List -Property verb,noun,module

For more information about PowerShell snap-ins, see about_PSSnapins.

The commands that a module exports should follow the PowerShell command naming rules. If the module that you import exports cmdlets or functions that have unapproved verbs in their names, the Import-Module cmdlet displays the following warning message.

WARNING: Some imported command names include unapproved verbs which might make them less discoverable. Use the Verbose parameter for more detail or type Get-Verb to see the list of approved verbs.

This message is only a warning. The complete module is still imported, including the non-conforming commands. Although the message is displayed to module users, the naming problem should be fixed by the module author.

To suppress the warning message, use the DisableNameChecking parameter of the Import-Module cmdlet.

Built-in Modules and Snap-ins

In PowerShell 2.0 and in older-style host programs in PowerShell 3.0 and later, the core commands that are installed with PowerShell are packaged in snap-ins that are added automatically to every PowerShell session.

Beginning in PowerShell 3.0, for host programs that implement the InitialSessionState.CreateDefault2 initial session state API the Microsoft.PowerShell.Core snap-in is added to every session by default. Modules are loaded automatically on first-use.

Note

Remote sessions, including sessions that are started by using the New-PSSession cmdlet, are older-style sessions in which the built-in commands are packaged in snap-ins.

The following modules (or snap-ins) are installed with PowerShell.

  • Microsoft.PowerShell.Archive
  • Microsoft.PowerShell.Core
  • Microsoft.PowerShell.Diagnostics
  • Microsoft.PowerShell.Host
  • Microsoft.PowerShell.Management
  • Microsoft.PowerShell.ODataUtils
  • Microsoft.PowerShell.Security
  • Microsoft.PowerShell.Utility
  • Microsoft.WSMan.Management
  • PackageManagement
  • PowerShellGet
  • PSDesiredStateConfiguration
  • PSReadline
  • PSScheduledJob
  • PSWorkflow
  • PSWorkflowUtility
  • ISE

Logging Module Events

Beginning in PowerShell 3.0, you can record execution events for the cmdlets and functions in PowerShell modules and snap-ins by setting the LogPipelineExecutionDetails property of modules and snap-ins to $True. You can also use a Group Policy setting, Turn on Module Logging, to enable module logging in all PowerShell sessions. For more information, see about_EventLogs and about_Group_Policy_Settings.

See Also

about_Command_Precedence

about_DesiredStateConfiguration

about_EventLogs

about_Group_Policy_Settings

about_PSSnapins

Get-Command

Get-Help

Get-Module

Import-Module

Remove-Module