Professional Windows® PowerShell

10.1. Enabling Scripts on Your Machine

At the time of this writing, the default configuration of Windows PowerShell when it is installed doesn't allow you to run scripts. If your local administrator has enabled scripts on your machine, then you may not need to take the steps described later in this section.

Windows PowerShell supports four execution policies, listed here. An execution policy determines whether you can run PowerShell scripts at all and which scripts you can run. The Restricted execution policy is the default. The four execution policies supported in Windows PowerShell 1.0 are:

• Restricted — Windows PowerShell operates as an interactive shell only. You cannot run any .ps1 scripts or .ps1xml configuration files at startup.

• AllSigned — Runs only scripts that have first been signed by a publisher that you trust. This includes scripts that you create on the local computer.

• RemoteSigned — Windows PowerShell runs locally authored scripts that are not digitally signed, but any scripts downloaded from applications like Internet Explorer and Microsoft Outlook must be signed by a publisher that you trust before you can run them.

• Unrestricted — PowerShell runs all scripts. Scripts downloaded from applications like Internet Explorer display a prompt that indicates that they have been downloaded.

If you attempt to run a script where the execution policy is Restricted and therefore forbids its execution, you will see an error message similar to the one in Figure 10-1.

Figure 10.1. ...