Professional Windows® PowerShell

Chapter 7. Filtering and Formatting Output

In this chapter, I cover two techniques that you may find useful to take control of your output. You look at how you can take the potentially enormous amount of information returned from some cmdlets and how to format and filter that information.

Filtering determines whether or not an object is passed on to the next step in a pipeline. You invoke filtering by using some cmdlets and specifying tests that determine what objects to pass along the pipeline. The where-object cmdlet is a powerful tool for filtering according to a test specified in a Windows PowerShell expression. You can also use the select-object cmdlet to select specified properties to be passed along the pipeline.

Formatting is concerned with the display of information, both in general and in determining where the objects are supplied to the final step in a pipeline. In many of the pipelines you have seen so far, there has been an invisible final step that uses the default formatter to define how the results of a command or pipeline are displayed. However, the default formatter doesn't always format the output in the way you need. Windows PowerShell provides two cmdlets, format-table and format-list, which allow you to take more control of the display of the information in objects that emerge from earlier steps in the pipeline.