Windows 7 : Scripting Windows with PowerShell - Getting Started with PowerShell

So when you’re executing commands in a PowerShell session, you’re essentially always executing a script, even if it’s a script that contains only a single command.

Starting a PowerShell Session

To get PowerShell up and running, select Start, type power, and then select Windows PowerShell in the search results. Windows 7 starts a new PowerShell console session, and displays it in the Windows PowerShell window, as shown in Figure 1.

Figure 1. Windows PowerShell is eerily similar to Command Prompt.

As you can see, on the surface PowerShell looks like a Command Prompt clone with its character-based console and command-line prompt. In fact, not only does PowerShell look like Command Prompt, it also works like Command Prompt. That is, almost anything you can do in a Command Prompt session you can also do in exactly the same way in a PowerShell session:

• PowerShell supports the standard Command Prompt commands, including cd, del, dir, echo, md, move, ren, rm, rmdir, set, sort, and start.

• PowerShell supports the standard DOSKEY techniques for recalling command lines and running multiple commands at once.

• You can use PowerShell to start batch files, script, and programs.

• PowerShell supports redirection (such as >) and piping (|).

• You can use PowerShell’s system menu (click the icon in the upper-left corner of the window) to select, copy, and paste text, just as with the Command Prompt window.

All this means that if you’re comfortable working with Command Prompt, you won’t have much of a learning curve when it comes to PowerShell (at least as far as the above techniques are concerned).

Understanding PowerShell Cmdlets

What truly separates PowerShell from Command Prompt is the concept of the cmdlet (pronounced “commandlet”), which is a PowerShell component that encapsulates some larger functionality into a single item. (If you’re familiar with Excel, a cmdlet is analogous to an Excel worksheet function.) The name of each PowerShell cmdlet takes the following general form:

verb-subject

Here, subject refers to some kind of object, and verb is some action that the cmdlet performs on that object. For example, you can use the Get-Host cmdlet to return information about the current PowerShell hosting environment, or you can use the Out-File cmdlet to output data to a file.

Although you can run most cmdlets with no other text, most of the time you’ll augment a cmdlet name with various parameters, depending on the cmdlet syntax. For example, you use the Write-Host cmdlet to write text to the hosting environment (which means the command line in a PowerShell console session), so you need to specify the text you want to write, as in this example:

write-host "Hello PowerShell World!"

I should also mention here that many cmdlets have alternate names called aliases that you can use. For example, the Get-Service cmdlet returns the current status of whatever service you specify, as in this example:

get-service w32time

However, Get-Service also uses the alias gsv, the following command is equivalent:

gsv w32time

Table 1 lists the PowerShell aliases