What Is Microsoft PowerShell?by Fraser Sherman
Windows PowerShell is a command-line shell for system administrators. By typing commands into PowerShell, administrators direct the operating system to carry out specific tasks. Working in PowerShell, administrators can automate some of their duties, control applications and manipulate items in the system's database. PowerShell runs on top of Microsoft's .NET operating environment, which gives the program capabilities other shells don't possess.
PowerShell's features include built-in commands -- cmdlets -- to manage computers in your network. Cmdlets perform common system administration tasks such as managing the registry; managing event logs; controlling services and processes; and using Windows Management Instrumentation. Cmdlets use the same syntax and naming conventions as Windows system data, which makes it easy for one cmdlet to send information to another without having to reformat or manipulate the data. Each cmdlet has a single, specific function, such as giving the date or fetching the event log.
To start PowerShell, click on the Windows "Start" button, then click "Programs" or "All Programs" depending on your edition of Windows. Then click, in order, on "Applications," "PowerShell Folder" and "PowerShell." If you need administrator privileges on the network, right-click "PowerShell" and then click "Run as Administrator." Microsoft has added instructions online (see Resources) for starting a customized PowerShell session that runs a particular command or script, or executes instructions according to a special policy.
PowerShell's tools include functions that perform the same services as cmdlets, but are much simpler to write code for if you have to create a function yourself. A snap-in is a library of links that implements cmdlets and functions. Modules are packages of commands you can import into a PowerShell session. Aliases are short names you can assign to cmdlets, to avoid typing the real names, which are long, every time you use them.
When you work in PowerShell you risk two types of errors. Terminating errors halt the execution of your commands, while commands with non-terminating errors continue running. If you direct PowerShell to remove certain files from the directory, but one file cannot be deleted, PowerShell continues removing the other files rather than terminating. If you give PowerShell a command that exceeds your admin authority or requires invalid data, the command terminates.