Windows 7 : Scripting Windows with PowerShell - Creating PowerShell Scripts

Setting the Script Execution Policy

By default, PowerShell is configured to not allow any unsigned scripts to run. That’s a sensible precaution on systems that don’t have a PowerShell programmer, but that’s not the case on your system. So, you need to configure PowerShell to allow your own scripts to run, and you do that by changing the PowerShell execution policy.

However, only the system Administrator account can change the PowerShell execution policy. That is, it’s not enough that your user account is a member of the Administrators group: It must be the Administrator account itself. Because you change the execution policy at the PowerShell prompt, you need to open a new PowerShell using the Administrator account:

With your Administrator PowerShell session loaded, enter the following command at the PowerShell prompt:

set-executionpolicy remotesigned

PowerShell displays the following message:

Execution Policy Change
The execution policy helps protect you from scripts that you do not trust. Changing
the execution policy might expose you to the security risks described in the
about_Execution_Policies help topic. Do you want to change the execution policy?
[Y] Yes [N] No [S] Suspend [?] Help (default is "Y"):

					  

Type y and press Enter (or just press Enter) to put the new policy into effect. You can now run your own scripts.

Working with the PowerShell Integrated Scripting Environment

Although you could easily use Notepad or some other text editor to create your scripts, you’re much better off using the PowerShell Integrated Scripting Environment (ISE), which includes programmer-friendly goodies such as color-coded syntax, breakpoints, stepping through scripts, and more.

To launch PowerShell ISE, select Start, type power, and then select PowerShell ISE in the search results. Figure 1 shows PowerShell ISE with a script loaded.

Figure 1. PowerShell ISE provides a powerful and efficient place to build your scripts.

The PowerShell ISE window is divided into three panes:

• Script pane— This is the top pane, and it’s where you type your script code. PowerShell ISE automatically color-codes your text to make it easier to read the code and to help you find errors. For example, cmdlets appear in blue; variables appear in red; comments appear in dark green; and strings appear in dark red.

• Command pane— This is the bottom pane, and it works pretty much like the PowerShell console. That is, you can use the prompt top enter PowerShell commands, which saves you having to open a separate PowerShell command-line session.

• Output pane— This is the middle pane, and it’s where PowerShell ISE displays the output from your script or from the commands you enter into the Command pane.

Running PowerShell Scripts

If you’re using the PowerShell ISE to compose your scripts, you don’t have to leave the application to run the current script. Instead, either click the Run button in the toolbar or press F5. PowerShell ISE runs that script within the window, and if your script has output, it’s displayed in the Output pane (the middle pane).

If you’re running a script from the PowerShell command line, you might think you can change to the folder where your script resides (using the command cd path, where path is the full pathname of the folder), type the name of the script, and then press Enter. That would be nice, but it isn’t likely to work. That’s because PowerShell is configured to run scripts only under the following circumstances:

• If the script is stored in a folder that’s part of your system’s Path environment variable

• If you specify the full pathname of the script

If you only run the occasional script and your PowerShell session is currently in your scripts folder, PowerShell offers a shortcut method for specifying the full pathname of the script. If you precede the script filename with a dot (.), PowerShell interprets that dot as the parent folder of the current folder, so it’s just the same as typing out the entire path.

For example, if you have a script named RegAdd.ps1 stored in the Documents\Scripts folder, you’d normally have to enter the following to run the script (where account is your user account name):

c:\users\account\documents\scripts\regadd.ps1

However, if you’ve got PowerShell in the Scripts folder, you can run the same script using the following command:

.\regadd.ps1

On the other hand, if you run lots of scripts, or if you want to be able to run your scripts from any folder, you need to add your Scripts folder to the Path variable. Here’s how it’s done: