Getting Summary Command Information in Windows PowerShell

The Windows PowerShell Get-Command cmdlet retrieves the names of all available commands. When you type Get-Command at a Windows PowerShell prompt, you will see output similar to the following:

This output looks a lot like the Help output of Cmd.exe: a tabular summary of internal commands. In the extract of the Get-Command command output shown above, every command shown has a CommandType of Cmdlet. A Cmdlet is Windows PowerShell's intrinsic command type that corresponds roughly to the dir and cd commands of Cmd.exe and to built-ins in UNIX shells such as BASH.

In the output of the Get-Command command, all of the definitions end with ellipses (...) to indicate that PowerShell cannot display all of the content in the available space. When Windows PowerShell displays output, it formats the output as text and then arranges it to make the data fit cleanly into a console window. We will talk about this later in the section on formatters.

The Get-Command cmdlet has a Syntax parameter that allows you to retrieve just the syntax of each cmdlet. Enter the Get-Command -Syntax command to display the full output:

Windows PowerShell Handles Console Input and Display

When you type a command, Windows PowerShell always processes the command-line input directly. Windows PowerShell also formats the output that you see on the screen. This is significant because it reduces the work required of each cmdlet and ensures that you can always do things the same way regardless of which cmdlet you are using. One example of how this simplifies life for both tool developers and users is command-line help.

Traditional command-line tools have their own schemes for requesting and displaying help. Some command-line tools use /? to trigger the help display; others use -?, /H, or even //. Some will display help in a GUI window, rather than in the console display. Some complex tools, such as application updaters, unpack internal files before displaying their help. If you use the wrong parameter, the tool might ignore what you typed and begin performing a task automatically.

When you enter a command in Windows PowerShell, everything you enter is automatically parsed and pre-processed by Windows PowerShell. If you use the -? parameter with a Windows PowerShell cmdlet, it always means "show me help for this command". Cmdlet developers do not have to parse the command; they only need to provide the help text.

It is important to understand that the help features of Windows PowerShell are available even when you run traditional command-line tools in Windows PowerShell. Windows PowerShell processes the parameters and passes the results to the external tools.

Note:

If you run an graphic application in Windows PowerShell, the window for the application opens. Windows PowerShell intervenes only when processing the command-line input you supply or the application output returned to the console window; it does not affect how the application works internally.