Introduction to Powershell

Basic

Basics

PS is a command line interpreter/scripting environment

Designed for .Net Similar to C# Easy to instantiate .Net classes

Standardized syntax PS is object based – not text based

This includes pipeline processing Reduces need for reading process to parse data

V1.0 does not naturally support remote execution.

Start Powershell

Start->Programs->Windows Powershell->Windows Powershell

At the command line

Expressions Cmdlet PowerShell Functions PowerShell Scripts Native Windows Commands

- Also - Supports direct interpolation

PS Drives

Let’s start by looking at the environment

PS Drives give you access to resources in a consistent manner – similar to Unix’s approach to files and devices

PS Drives provide access to folders/files, the registry, existing functions and variables etc

Enter the following at the command line:

Get-PSDrive

Experience exercise

Enter the following lines at the command prompt and observe the behavior:#Key in this line and the rest below

54

(54 * 3 ) – 2

"Patrick is " + 54

Get-Date

Operators

() {} - Grouping++ , -- Increment, decrement, respectively+ , - Unary operator* or *= Multiplication. / or /= Division. % or %= Modulus+ or += Addition. -  or -= Subtraction. = Assigns a value to a variable

Standard rules of precedence apply.

.Net CLR Types

In .Net everything is an object.

Powershell Data types

Type Description

[int] 32-bit signed integer

[long] 64-bit signed integer

[string] Fixed-length string of Unicode characters

[char] A Unicode 16-bit character

[byte] An 8-bit unsigned character

[bool] Boolean True/False value

[decimal] An 128-bit decimal value

[single] Single-precision 32-bit floating point number

[double] Double-precision 64-bit floating point number

[xml] Xml object

[array] An array of values

[hashtable] Hashtable object

Exploring on your own

129 + "1""1" + 129[int]"0129" + 1[datetime]"10/20/2009""We are meeting on " + get-date"We are meeting on " + (get-date)

Expressions are objects

Let’s explore this by entering the following

(120).GetType()"Patrick Bailey".GetType()"Patrick Bailey".ToUpper()“Pat has " + "Pat".Length + " letters."(Get-Date).AddYears(-5)

Variables while we’re at it

$a = 123.45$a.GetType()$b = "Patrick"$b.GetType()

Convenient here-string

Arrays

$a = 1,2,3,4,7,"How do you do", 9,(Get-Date)$a$a[2]$a[3..6]$a[-1]

Hashtables$list = @{"St Paul" = [datetime]"10/20/2009"; ` "Minneapolis" = [datetime]"11/17/2009"}$list$list["St Paul"]

Line continuation

Cmdlets

Cmdlets are instances of .NET Framework classes; they are not stand-alone executables.

Cmdlets do not generally do their own parsing, error presentation, or output formatting. Parsing, error presentation, and output formatting are handled by the Windows PowerShell runtime.

Cmdlets process input objects from the pipeline rather than from streams of text, and cmdlets typically deliver objects as output to the pipeline.

Cmdlets are record-oriented because they process a single object at a time.http://msdn.microsoft.com/en-us/library/ms714395%28VS.85%29.as

px

Cmdlet(A compiled application for the PS environment)

131 Cmdlets in v1.0, 237+ in V2.0 verb-noun naming (e.g. get-

childitem) Elements of a command :

command -parameter1 -parameter2 arg1 arg2Command

Name

SwitchParameter

Parameter withargument

PositionalArgument

Ref: http://technet.microsoft.com/en-us/library/dd315315.aspx

Exploring datetime object

Information about the system

Enter each of these and observe

Get-CommandGet-Command -Verb SetnotepadGet-ProcessGet-Process notepadGet-Service -Name *sql*

Ref: http://technet.microsoft.com/en-us/library/dd315315.aspx

Some standard named params -ErrorAction

Behavior when an error occurs. Values include SilentlyContinue, Continue (defualt), Stop

-Confirm Before execution the command will ask user for

continuation option. Mostly available with commands that alter resources.

-ErrorVariable Variable to assign error object to.

-WhatIfDescribes the action that would be taken – does

not execute command

Try these one at a time…

Set-Content demofile.txt "Hello`nThis is the second line." –Confirm

Get-Content demofile.txt -OutVariable txtContent

$txtContent

Remove-Item demofile.txt –WhatIf

Remove-Item demofile.txt

Remove-Item demofile.txt #yes this repeats it

Remove-Item demofile.txt -ErrorAction SilentlyContinue

Filter cmdlets and the pipeline

Most cmdlets, as you have seen, produce objects for their output. Literal values do the same.

Get-Member provides a listing of the public members of those objects

By default it displays public instance members

Taking it one step further

The pipeline

Similar to traditional scripting languages

BUT it “pipes” objects – specifically .Net objects

Access to data is through methods and properties – not string parsing*

*Of course, any property of type string has the expected set of methods for returningmodifications of the string.

Examples of Get-Member

"Pat winks" | Get-Member

Get-Process | Get-Member

[Int32] | Get-Member

[Int32] | Get-Member –Static

[Int32]::MaxValue

A closer look

“It’s not rude to point”

notepad;notepad

$plist = Get-Process notepad$p1 = $plist[0]$p1 | Get-Member

$p1.HasExited

Stop-Process -Id $p1.Id

$p1.HasExited

Filtering in action

notepad;notepad;notepad

Get-Process | Where-Object { $_.Name -eq "notepad" }

Get-Process | Select-Object Handles, Id, ProcessName

Get-Process -Name notepad | ForEach-Object { Stop-Process $_.Id }

What was that?

Script blocks – think of them as anonymous methods or short inline scripts

$_ is similar to Perl’s use as the current value in process

Group-Object

Grouping Objects get-childitem C:\temp | group-object extension

Service Cmdlets

get-service new-service restart-service set-service stop-service start-service

Starting and Stopping a Service