Windows 7 / Getting Started

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PowerShell Commands

PowerShell includes three types of commands that can be executed or scripted:

Cmdlets PowerShell cmdlets are built-in commands. They are different from commandprompt commands in that they are tightly integrated with Microsoft's .NET Framework, providing a much richer set of capabilities. You can think of them as mini-programs. Many cmdlets can accept parameters and return values. Values can be displayed, assigned to variables, or passed to other cmdlets or functions.

As an example, the Get-Command cmdlet will retrieve a list of all PowerShell commands. You can modify the command with parameters to alter the results. For example, the following three commands can be used to retrieve a list of only the cmdlets, only the aliases, and only the functions. In these examples, the Get-Command cmdlet is being used with the -CommandType switch, and cmdlet, alias, and function are the parameters passed to the Get-Command cmdlet.

Get-Command -CommandType cmdlet
Get-Command -CommandType alias
Get-Command -CommandType function

Aliases An alias is another name for a cmdlet. Many command-prompt commands have been rewritten as PowerShell commands. While the actual PowerShell command is different from the command-prompt command, many aliases have been created so that you enter the command-prompt command and it will launch the PowerShell command.

As an example, the CD command-prompt command is used to change the current directory. The PowerShell cmdlet is Set-Location, but CD is recognized as an alias for Set-Location. Try it. These two commands achieve the same result of changing the current path to the root of the C: drive:

CD \
Set-Location \

All command-prompt commands have not been rewritten. If you enter a command such as path, which works at the command prompt, you'll see it doesn't work here. You can enter the Get-Alias command to get a list of all the aliases supported within PowerShell. In addition, some longer cmdlets have been rewritten as aliases. As an example, the Get-WMIObject cmdlet has an alias of gwmi.

Functions A function is a type of command that you can run within PowerShell or PowerShell scripts. They are very similar to cmdlets. They can accept parameters and can return values that are displayed, assigned to variables, or passed to other functions or cmdlets.

A commonly used function is the Help function, which provides help on PowerShell topics and concepts. When executed without a parameter, it provides one set of information. When a valid PowerShell command is added as a parameter (such as Help Get-Command), it provides specific help on the command. Another function that is commonly used is the drive letter (such as C:, D:, and so on). It will change the current PowerShell prompt location to the named drive. You can also create your own functions.

Any of these commands can be executed from the PowerShell prompt or embedded into PowerShell scripts. Also, many server applications (such as Internet Information Services (IIS), Exchange Server 2007, and Exchange Server 2010) are heavily intertwined with PowerShell commands. In other words, what you learn here on Windows 7 will be useful when you're managing servers.