PowerShell is a command line and scripting utility for use with Windows.
Questions about Windows administration tasks involving PowerShell should be asked on Super User. On-topic questions are for writing scripts ONLY
Windows PowerShell
powershell is an interactive shell and scripting language originally included with Microsoft Windows 7 and Microsoft Windows Server 2008 R2 and above. It includes a command-line shell (Windows PowerShell) for interactive use, an underlying scripting environment to run scripts away from the command-line and a GUI script editing / debugging environment (Windows PowerShell ISE). See: Getting Started with Windows PowerShell.
As a language, powershell has syntax for literal arrays and hashtables, support for regexes, pattern matching and string expansion. It's built on the .NET framework so it has Unicode support, can be locale/culture aware, and can access .NET framework methods directly.
As a command-line shell, it is designed around cmdlets named in the form {Verb}-{Noun}, intending that the same kinds of commands work across many domains. E.g. Get-Date returns the current date, and Get-Process returns an array of objects representing running processes which can be piped to other commands that work with process objects. Many commands and keywords have short aliases to reduce typing.
As a system management environment, Windows components and Microsoft products have been extended to provide native PowerShell interfaces as part of creating a unified managing system for Windows systems, including:
- EventLogs, Task Scheduler, WMI, COM objects.
- Active Directory, Hyper-V, IIS, Remote Desktop Services and other Roles and Features
- Exchange Server
- SQL Server
- SharePoint
- Dynamics CRM
- Windows Azure cloud services
- Office 365
- As well as the usual scripting tasks — working with files/folders, user accounts, string manipulation, running external programs, etc.
Third-party vendors also offer PowerShell integration, including:
powershell takes the Unix idea of piping text between programs and manipulating text, and enhances it by piping .NET object instances around. Because objects carry type information (e.g. dates and times), and complex state (e.g. properties and methods, hashtables, parsed XML data, live network sockets) this makes many tasks easy that would be difficult or impractical to do by passing text between programs.
Along with interacting with the PowerShell console or the PowerShell ISE, there are also several 3rd party IDE options including Sapien's PrimalScript ISE.
Example Usage
# List all processes using > 100 MB of PagedMemory in descending sort order (v3_
C:\PS> Get-Process | Where PagedMemorySize -GT 100MB | Sort -Descending
PowerShell can handle numbers and arithmetic
C:\PS> (98.6 - 32) * 5/9
37
Production orientation allows experimentation and confirmation
C:\PS> Get-ChildItem C:\Users\John *.bak -r |
Where {$_.LastWriteTime -gt (Get-Date).AddDays(-7)} |
Remove-Item -WhatIf
What if: Performing operation "Remove File" on Target "C:\Users\John\foo.bak"
C:\PS> Get-Process iexp* | Stop-Process -Confirm
Confirm
Are you sure you want to perform this action?
Performing operation "Stop-Process" on Target "iexplore (7116)".
[Y] Yes [A] Yes to All [N] No [L] No to All [S] Suspend [?] Help (default is Y):
Common Gotchas
Executing EXEs via a path with spaces requires quoting the path and the use of the call operator - &
C:\PS> & 'C:\Program Files\Windows NT\Accessories\wordpad.exe'
Calling PowerShell functions does not require parenthesis or comma separated arguments. PowerShell functions should be called just like a cmdlet. The following examples demonstrates the problem caused by this issue e.g.:
C:\PS> function Greet($fname, $lname) {"My name is '$lname', '$fname' '$lname'"}
C:\PS> Greet('James','Bond') # Wrong way to invoke this function!!
My name is '', 'James Bond' ''
Note that both 'James' and 'Bond' are packaged up as a single argument (an array) that is passed to the first parameter. The correct invocation is:
C:\PS> Greet James Bond
My name is 'Bond', 'James' 'Bond'
Note that in PowerShell 2.0, the use of Set-StrictMode -version 2.0 will catch this type of problem.
Extensible functionalities
One of the great features of Powershell is its extensibility: we can add functionality by importing modules which are package of cmdlets, functions and aliases specialised on a particular domain (such as database administration, virtual machine administration etc.).
Here are the most commonly used modules by the community :
PSReadLine
"PSReadLine replaces the command line editing experience in PowerShell.exe for versions 3 and up." Included in Windows 10.Powertab
"PowerTab offers enhanced tab expansion for PowerShell."PSCX
"PowerShell Community Extensions (PSCX) is aimed at providing a widely useful set of additional cmdlets, providers, aliases, filters, functions and scripts for Windows PowerShell that members of the community have expressed interest in but haven't been added to PowerShell yet."
Resources
