Introduction

PowerShell is an administrative tool that has both shell and scripting capabilities that can leverage Windows Management Instrumentation (WMI), COM components, and .NET libraries. PowerShell is becoming more prominent with each generation of Microsoft products. Support for it is being bundled, and improved, in a number of new and upcoming Microsoft product releases. Windows Server, Exchange, ActiveDirectory, SharePoint, and even SQL Server, have all shipped with added PowerShell support and cmdlets. Even vendors such as VMWare, Citrix, Cisco, and Quest, to name a few, have provided ways to allow their products to be accessible via PowerShell.

What makes PowerShell tick? Every systems administrator probably knows the pain of trying to integrate heterogeneous systems using some kind of scripting. Historically, the solution involved some kind of VBScript, some good old batch files, maybe some C# code, some Perl—you name it. Sysadmins either had to resort to duct taping different languages together to get things to work the way they intended, or just did not bother because of the complicated code.

This is where PowerShell comes in. One of the strongest points for PowerShell is that it simplifies automation and integration between different Microsoft ecosystems. As most products have support for PowerShell, getting one system to talk to another is just a matter of discovering what cmdlets, functions, or modules need to be pulled into the script. Even if the product does not have support yet for PowerShell, it most likely has .NET or COM support, which PowerShell can easily use.

Notable PowerShell V3 features

Some of the notable features in the latest PowerShell version are:

• Workflows: PowerShell V3 introduces Windows PowerShell Workflow (PSWF), which as stated in MSDN (http://msdn.microsoft.com/en-us/library/jj134242.aspx):

  helps automate the distribution, orchestration, and completion of multi-computer tasks, freeing users and administrators to focus on higher-level tasks.

  PSWF leverages Windows Workflow Foundation 4.0 for the declarative framework, but using familiar PowerShell syntax and constructs.

• Robust sessions: PowerShell V3 supports more robust sessions. Sessions can now be retained amid network interruptions. These sessions will remain open until they time out.

• Scheduled jobs: There is an improved support for scheduled tasks. There are new cmdlets in the PSScheduledJob module that allow you to create, enable, and manage scheduled tasks.

• Module AutoLoading: If you use a cmdlet that belongs to a module that hasn't been loaded yet, this will trigger PowerShell to search PSModulePath and load the first module that contains that cmdlet. This is something we can easily test:

  #check current modules in session
  Get-Module
  
  #use cmdlet from CimCmdlets module, which
  #is not loaded yet
  Get-CimInstance win32_bios 
  
  #note new module loaded CimCmdlets
  Get-Module 
  
  #use cmdlet from SQLPS module, which
  #is not loaded yet
  Invoke-Sqlcmd -Query "SELECT GETDATE()" -ServerInstance "KERRIGAN"
  
  #note new modules loaded SQLPS and SQLASCmdlets 
  Get-Module

• Web service support: PowerShell V3 introduces the Invoke-WebRequest cmdlet, which sends HTTP or HTTPS requests to a web service and returns the object-based content that can easily be manipulated in PowerShell. You can think about downloading entire websites using PowerShell (and check out Lee Holmes' article on it: http://www.leeholmes.com/blog/2012/03/31/how-to-download-an-entire-wordpress-blog/).

• Simplified language syntax: Writing your Where-Object and Foreach-Object has just become cleaner. Improvements in the language include supporting default parameter values, and simplified syntax.

  What you used to write in V1 and V2 with curly braces and $_ as follows:

  Get-Service | Where-Object { $_.Status -eq 'Running' }

  can now be rewritten in V3 as:

  Get-Service | Where-Object Status -eq 'Running'

• Improved Integrated Scripting Environment (ISE): The new ISE comes with Intellisense, searchable commands in the sidebar, parameter forms, and live syntax checking.