To start at the very beginning, we answer the most
basic question, “What is PowerShell?” PowerShell is a command-based
shell and scripting language built on the .NET framework with
incredible power and versatility designed especially for system
administration. The latest version as of this writing is version 2.0
and it was officially released on October 28, 2009. We say shell and
scripting language because both components can be used separately. At
its fundamental level, it is a command-based shell in a console-like
interface that will allow you to simply issue it commands and call its
powerful scripting language to accomplish what tasks you need it to do.
In this interactive use, you directly issue commands to the console and
it performs the desired tasks. The other powerful part of PowerShell
that takes full advantage of the underlying scripting language is the
ability to run longer or complex instructions from a script. This
allows you to automate some of the tasks you might need to perform. The
final piece which is brand new to version 2.0 is the ability to run
commands on one or more computers from a single computer running
PowerShell. These abilities together should allow you to tackle almost
any job without problem.
Another aspect of PowerShell you need to become
familiar with is its command syntax. The commands PowerShell uses are
called cmdlets. It is through these simple instructions that you will
be performing all the common system administration tasks. cmdlets all
share a similar syntax composed of a verb and a noun in a verb-noun
format. As an example, we will use one of the most helpful commands,
get-help. The get-help cmdlet is an easy example. Typing Get-help
followed by the subject or command you want to get help about will get
you more information about it. It will either give you the help you
need or give you a list of subjects so that you can narrow it down to
which one you need (Table 1).
Table 1. Getting Help Is Easy
| cmdlet | Description |
|---|
| Get-Help about | Will list all the subjects that start with about |
| Get-Help about_scripts | Will get the specific help file about_scripts |
| Get-Help *about* | Will give you a list of all the subjects that have “about” anywhere in them |
As you can see, the main goal of Windows PowerShell
is to give the administrator more control over the system and make it
easier to perform the required tasks. It increases the administrator’s
bag of tools by adding automation and remoting and their associated
advantages. Imagine only having to write a command once and then being
able to run it multiple times on different machines. This eliminates
the need to run the same thing over and over by simply having
PowerShell let you run it multiple times. It also eliminates some of
the human error aspects since you only need to write it once and
therefore only check it once.
What is new in PowerShell V2
Version 2.0 of Windows PowerShell was officially
released on October 28, 2009 after much anticipation by the PowerShell
community. It introduces a large amount of new features that were not
available before. It stays true to its purpose of making system
administration easier by adding remoting, debugging tools and other
things to the administrator’s new shiny toolkit.
Of all the new features in Windows PowerShell
version 2.0, the one feature that seems to elicit cheers and get the
most attention is the new remote management or remoting feature.
PowerShell supports interactive remoting where you connect directly and
issue commands, fan-in (1 pc to
many) and fan out (many pcs to 1). It allows the administrator to run
scripts on one or many remote computers with a single command. Gone are
the days of tediously going to different computers and running the same
script on each of them one at a time. Gone are the days of taking your
preferred script and copying it from machine to machine. Now, all you
have to do is establish a session to the other computer or computers
you want to run the script on and then issue the commands. From running
a single cmdlet to a whole script, it is that simple. PowerShell 2.0
does have to be installed on the computers you are running the scripts
on, the originating one and the target ones.
Another new feature sorely lacking from the earlier
versions of PowerShell is the ability to run background jobs. This new
ability of PowerShell version 2.0 to run background jobs allows you to
asynchronously run other jobs or processes in the background while you
continue to work on your session. You issue the command for the
background job and immediately get the prompt back so that you can
continue to work while the background job executes. These background
jobs can be run on your local machine or on a remote computer.
Windows PowerShell 2.0 has also included new script
debugging capabilities. Included now is the built-in capability to
debug your scripts. It allows you to set breakpoints, step through
code, monitor variable values, and more. It also allows you to decide
what actions to take when the break point is hit. These capabilities
give you the tools necessary to debug all your scripts with relative
ease.
Another new feature is that of eventing. Eventing is
the new capability of PowerShell to handle and react to events. It now
includes an infrastructure that not only can listen for system and
application events and act based on them. In addition, you can now
create your own events which allow you to set up a chain of actions
based on what your scripts do.
The new version also comes with a large number of
new cmdlets. PowerShell version 2.0 introduces a little over 100 new
cmdlets with numerous capabilities. All these cmdlets range from all
the new functionalities mentioned earlier to powerful logging tools and
mail-sending cmdlets.
PowerShell 2.0 also supports script internalization.
This allows PowerShell to display messages in multiple languages. In
addition to the regular get-help command and man command at the command
line, PowerShell includes online help via a parameter to the get-help
command. Using get-help, the command to get help on and then the online
parameter opens a browser for you with the command help in Microsoft
TechNet.
Another
new feature is the support of Modules. A module is a package that
includes Windows PowerShell commands like cmdlets, providers, aliases,
and variables. PowerShell now lets you create these modules and
organize your commands so that you can share them with others.
PowerShell version 2.0 has also included a lot of advanced functions.
These functions behave just like cmdlets but they are fully written in
the Windows PowerShell scripting language as opposed to C#.
Another new feature that PowerShell 2.0 has
brought is the new Integrated Scripting Environment or ISE. The
PowerShell ISE lets you run commands and scripts in an integrated
development environment (IDE). It allows you to edit and debug your
scripts with many options to figure out what is wrong and where it is
going wrong like most graphical interfaces. It makes writing cmdlets
easier with multiline editing and line and column numbers. It includes
color coding like most graphical interfaces which makes it very easy
for the user to write and execute their own commands by immediately
showing them if they have made any syntax errors. It has several panes
or windows to make it easier to see what is going on. One pane to write
your command(s), one to show your scripts, and one to show you the
output or results of your commands or scripts. In essence, it makes it
really easy to get started with PowerShell by giving the user the tools
to create what they want quickly and easily.
