Powershell – Overview

Windows PowerShell is a command-line shell and scripting language designed especially for system administration. It”s analogue in Linux is called as Bash Scripting. Built on the .NET Framework, Windows PowerShell helps IT professionals to control and automate the administration of the Windows operating system and applications that run on Windows Server environment.

Windows PowerShell commands, called cmdlets, let you manage the computers from the command line. Windows PowerShell providers let you access data stores, such as the Registry and Certificate Store, as easily as you access the file system.

In addition, Windows PowerShell has a rich expression parser and a fully developed scripting language. So in simple words you can complete all the tasks that you do with GUI and much more.

PowerShell ISE

The Windows PowerShell Integrated Scripting Environment (ISE) is a host application for Windows PowerShell. In Windows PowerShell ISE, you can run commands and write, test, and debug scripts in a single Windows-based graphic user interface with multiline editing, tab completion, syntax coloring, selective execution, context-sensitive help, and support for right-to-left languages.

You can use menu items and keyboard shortcuts to perform many of the same tasks that you would perform in the Windows PowerShell console. For example, when you debug a script in the Windows PowerShell ISE, to set a line breakpoint in a script, right-click the line of code, and then click Toggle Breakpoint.

PowerShell Basic Commands

There are a lot of PowerShell commands and it is very difficult to put in all these commands in this tutorial, we will focus on some of the most important as well as basic commands of PowerShell.

The first step is to go to the Get-Help command which gives you an explanation about how to give a command and its parameter.

Powershell – Environment Setup

PowerShell Icon can be found in the task bar and in the start menu. Just by clicking on the icon, it will open.

To open it, just click on the icon and then the following screen will open and it means that PowerShell is ready for you to work on.

PowerShell Version

The latest version of PowerShell is 5.0 and to check what is installed in our server we type the following command – :$PSVersionTable as shown in the following screenshot and from the screen we also know that we have PSVersion 4.0

To update with the latest version where it has more Cmdlets we have to download Windows Management Framework 5.0 from the following link − https://www.microsoft.com/en-us/download/details.aspx?id=50395 and install it.

PowerShell ISE

The Windows PowerShell Integrated Scripting Environment (ISE) is a host application for Windows PowerShell. In Windows PowerShell ISE, you can run commands and write, test, and debug scripts in a single Windows-based graphic user interface with multiline editing, tab completion, syntax coloring, selective execution, context-sensitive help, and support for right-to-left languages.

You can use menu items and keyboard shortcuts to perform many of the same tasks that you would perform in the Windows PowerShell console. For example, when you debug a script in the Windows PowerShell ISE, to set a line breakpoint in a script, right-click the line of code, and then click Toggle Breakpoint.

To open it you just go to Start – Search and then Type – PowerShell as shown in the following screenshot.

Then click on Windows PowerShell ISE. Or click on the downward Arrow as shown in the following screenshot.

It will list all the applications installed on the server and then click on Windows PowerShell ISE.

The following table will be open −

It has three sections, which include – The PowerShell Console with number 1, then Scripting File number 2 and the third is the Command Module where you can find the module.

While creating the script you can run directly and see the result like the following example −

PowerShell Basic Commands

There are a lot of PowerShell commands and it is very difficult to put in all these commands in this tutorial, we will focus on some of the most important as well as basic commands of PowerShell.

The first step is to go to the Get-Help command which gives you an explanation about how to give a command and its parameter.

To get the list of Updates −

• Get-HotFix and to install a hot fix as follows
• Get-HotFix -id kb2741530

Powershell – cmdlets

A cmdlet or “Command let” is a lightweight command used in the Windows PowerShell environment. The Windows PowerShell runtime invokes these cmdlets at command prompt. You can create and invoke them programmatically through Windows PowerShell APIs.

Cmdlet vs Command

Cmdlets are way different from commands in other command-shell environments in the following manners −

• Cmdlets are .NET Framework class objects; and not just stand-alone executables.

• Cmdlets can be easily constructed from as few as a dozen lines of code.

• Parsing, error presentation, and output formatting are not handled by cmdlets. It is done by the Windows PowerShell runtime.

• Cmdlets process works on objects not on text stream and objects can be passed as output for pipelining.

• Cmdlets are record-based as they process a single object at a time.

Getting Help

The first step is to go to the Get-Help command which gives you an explanation about how to give a command and its parameter.

Powershell – Files and Folder Operations

Following are the examples of powershell scripts on Files and Folders.

Powershell – Date and Time Operations

Following are the examples of powershell scripts on System Date and Time.

Powershell – File I/O Operations

Following are the examples of powershell scripts of creating and reading different types of files.

Powershell – Advanced Cmdlets

Cmdlets

A cmdlet or “Command let” is a lightweight command used in the Windows PowerShell environment. The Windows PowerShell runtime invokes these cmdlets at command prompt. You can create and invoke them programmatically through Windows PowerShell APIs. Following are advanced usage example of cmdlets.

Powershell – Scripting

Windows PowerShell is a command-line shell and scripting language designed especially for system administration. Its analogue in Linux is called as Bash Scripting. Built on the .NET Framework, Windows PowerShell helps IT professionals to control and automate the administration of the Windows operating system and applications that run on Windows Server environment.

Windows PowerShell commands, called cmdlets, let you manage the computers from the command line. Windows PowerShell providers let you access data stores, such as the Registry and Certificate Store, as easily as you access the file system.

In addition, Windows PowerShell has a rich expression parser and a fully developed scripting language. So in simple words you can complete all the tasks that you do with GUI and much more. Windows PowerShell Scripting is a fully developed scripting language and has a rich expression parser/

Features

• Cmdlets − Cmdlets perform common system administration tasks, for example managing the registry, services, processes, event logs, and using Windows Management Instrumentation (WMI).

• Task oriented − PowerShell scripting language is task based and provide supports for existing scripts and command-line tools.

• Consistent design − As cmdlets and system data stores use common syntax and have common naming conventions, data sharing is easy. The output from one cmdlet can be pipelined to another cmdlet without any manipulation.

• Simple to Use − Simplified, command-based navigation lets users navigate the registry and other data stores similar to the file system navigation.

• Object based − PowerShell possesses powerful object manipulation capabilities. Objects can be sent to other tools or databases directly.

• Extensible interface. − PowerShell is customizable as independent software vendors and enterprise developers can build custom tools and utilities using PowerShell to administer their software.

Variables

PowerShell variables are named objects. As PowerShell works with objects, these variables are used to work with objects.

Creating variable

Variable name should start with $ and can contain alphanumeric characters and underscore in their names. A variable can be created by typing a valid variable name.

Type the following command in PowerShell ISE Console. Assuming you are in D:test folder.

$location = Get-Location

Here we”ve created a variable $location and assigned it the output of Get-Location cmdlet. It now contains the current location.

Using variable

Type the following command in PowerShell ISE Console.

 $location

Output

You can see following output in PowerShell console.

Path                                                                                    
----                                                                                    
D:test                                                                                 

Getting information of variable

Get-Member cmdlet can tell the type of variable being used. See the example below.

 $location | Get-Member

Output

You can see following output in PowerShell console.

   TypeName: System.Management.Automation.PathInfo

Name          MemberType   Definition                                               
----          ----------   ----------                                               
Equals        Method       bool Equals(System.Object obj)                           
GetHashCode   Method       int GetHashCode()                                        
GetType       Method       type GetType()                                           
ToString      Method       string ToString()                                        
Drive         Property     System.Management.Automation.PSDriveInfo Drive {get;}    
Path          Property     System.String Path {get;}                                
Provider      Property     System.Management.Automation.ProviderInfo Provider {get;}
ProviderPath  Property     System.String ProviderPath {get;}

Powershell – Special Variables

PowerShell Special variables store information about PowerShell. These are also called automatic variables. Following is the list of automatic variables −

Powershell – Operators

PowerShell provides a rich set of operators to manipulate variables. We can divide all the PowerShell operators into the following groups −

• Arithmetic Operators
• Assignment Operators
• Comparison Operators
• Logical Operators
• Redirectional Operators
• Spilt and Join Operators
• Type Operators
• Unary Operators

The Arithmetic Operators

Arithmetic operators are used in mathematical expressions in the same way that they are used in algebra. The following table lists the arithmetic operators −

Assume integer variable A holds 10 and variable B holds 20, then −

Show Examples

The Comparison Operators

Following are the assignment operators supported by PowerShell language −

Assume integer variable A holds 10 and variable B holds 20, then −

Show Examples

The Assignment Operators

Following are the assignment operators supported by PowerShell language −

Show Examples

The Logical Operators

The following table lists the logical operators −

Assume Boolean variables A holds true and variable B holds false, then −

Show Examples

Miscellaneous Operators

Following are various important operators supported by PowerShell language −

Show Examples

Powershell – Looping

There may be a situation when you need to execute a block of code several number of times. In general, statements are executed sequentially: The first statement in a function is executed first, followed by the second, and so on.

Programming languages provide various control structures that allow for more complicated execution paths.

A loop statement allows us to execute a statement or group of statements multiple times and following is the general form of a loop statement in most of the programming languages −

PowerShell programming language provides the following types of loop to handle looping requirements. Click the following links to check their detail.

Powershell – Conditions

Decision making structures have one or more conditions to be evaluated or tested by the program, along with a statement or statements that are to be executed if the condition is determined to be true, and optionally, other statements to be executed if the condition is determined to be false.

Following is the general form of a typical decision making structure found in most of the programming languages −

PowerShell scripting language provides following types of decision making statements. Click the following links to check their detail.

Powershell – Array

PowerShell provides a data structure, the array, which stores a fixed-size sequential collection of elements of the any type. An array is used to store a collection of data, but it is often more useful to think of an array as a collection of variables or objects.

Instead of declaring individual variables, such as number0, number1, …, and number99, you declare one array variable such as numbers and use numbers[0], numbers[1], and …, numbers[99] to represent individual variables.

This tutorial introduces how to declare array variables, create arrays, and process arrays using indexed variables.

Declaring Array Variables

To use an array in a program, you must declare a variable to reference the array, and you can specify the type of array the variable can reference. Here is the syntax for declaring an array variable −

Syntax

$A = 1, 2, 3, 4
or
$A = 1..4  

Note − By default type of objects of array is System.Object. GetType() method returns the type of the array. Type can be passed.

Example

The following code snippets are examples of this syntax −

[int32[]]$intA = 1500,2230,3350,4000

$A = 1, 2, 3, 4
$A.getType()

This will produce the following result −

Output

IsPublic    IsSerial    Name                        BaseType                     
--------    --------    ----                        --------                     
True        True        Object[]                    System.Array 

The array elements are accessed through the index. Array indices are 0-based; that is, they start from 0 to arrayRefVar.length-1.

Example

Following statement declares an array variable, myList, creates an array of 10 elements of double type and assigns its reference to myList −

$myList = 5.6, 4.5, 3.3, 13.2, 4.0, 34.33, 34.0, 45.45, 99.993, 11123

Following picture represents array myList. Here, myList holds ten double values and the indices are from 0 to 9.

Processing Arrays

When processing array elements, we often use either for loop or foreach loop because all of the elements in an array are of the same type and the size of the array is known.

Example

Here is a complete example showing how to create, initialize, and process arrays −

$myList = 5.6, 4.5, 3.3, 13.2, 4.0, 34.33, 34.0, 45.45, 99.993, 11123

write-host("Print all the array elements")
$myList

write-host("Get the length of array")
$myList.Length

write-host("Get Second element of array")
$myList[1]

write-host("Get partial array")
$subList = $myList[1..3]

write-host("print subList")
$subList

write-host("using for loop")
for ($i = 0; $i -le ($myList.length - 1); $i += 1) {
   $myList[$i]
}

write-host("using forEach Loop")
foreach ($element in $myList) {
   $element
}

write-host("using while Loop")
$i = 0
while($i -lt 4) {
   $myList[$i];
   $i++
}

write-host("Assign values")
$myList[1] = 10
$myList

This will produce the following result −

Output

Print all the array elements
5.6
4.5
3.3
13.2
4
34.33
34
45.45
99.993
11123
Get the length of array
10
Get Second element of array
4.5
Get partial array
print subList
4.5
3.3
13.2
using for loop
5.6
4.5
3.3
13.2
4
34.33
34
45.45
99.993
11123
using forEach Loop
5.6
4.5
3.3
13.2
4
34.33
34
45.45
99.993
11123
using while Loop
5.6
4.5
3.3
13.2
Assign values
5.6
10
3.3
13.2
4
34.33
34
45.45
99.993
11123

The Arrays Methods Examples

Here is a complete example showing operations on arrays using its methods

$myList = @(0..4)

write-host("Print array")
$myList

$myList = @(0..4)

write-host("Assign values")
$myList[1]  = 10
$myList

This will produce the following result −

Output

Clear array
Print array
0
1
2
3
4
Assign values
0
10
2
3
4

Powershell – Hashtables

Hashtable stores key/value pairs in a hash table. When using a Hashtable, you specify an object that is used as a key, and the value that you want linked to that key. Generally we used String or numbers as keys.

This tutorial introduces how to declare hashtable variables, create hashtables, and process hashtable using its methods.

Declaring hashtable Variables

To use an hashtable in a program, you must declare a variable to reference the hashtable. Here is the syntax for declaring an hashtable variable −

Syntax

$hash = @{ ID = 1; Shape = "Square"; Color = "Blue"}
or
$hash = @{} 

Note − Ordered dictionaries can be created using similar syntax. Ordered dictionaries maintain the order in which entries are added whereas hashtables do not.

Example

The following code snippets are examples of this syntax −

$hash = [ordered]@{ ID = 1; Shape = "Square"; Color = "Blue"}

Print the hashtable.

$hash

Output

Name                           Value    
----                           -----                                                    
ID                             1                                                        
Color                          Blue                                                     
Shape                          Square 

The hashtable values are accessed through the keys.

> $hash["ID"]
 1

Processing Hashtable

Dot notation can be used to access hashtables keys or values.

> $hash.keys
ID
Color
Shape

> $hash.values
1
Blue
Square

Example

Here is a complete example showing how to create, initialize, and process hashtable −

$hash = @{ ID = 1; Shape = "Square"; Color = "Blue"}

write-host("Print all hashtable keys")
$hash.keys

write-host("Print all hashtable values")
$hash.values

write-host("Get ID")
$hash["ID"]

write-host("Get Shape")
$hash.Number

write-host("print Size")
$hash.Count

write-host("Add key-value")
$hash["Updated"] = "Now"

write-host("Add key-value")
$hash.Add("Created","Now")

write-host("print Size")
$hash.Count

write-host("Remove key-value")
$hash.Remove("Updated")

write-host("print Size")
$hash.Count

write-host("sort by key")
$hash.GetEnumerator() | Sort-Object -Property key

This will produce the following result −

Output

Print all hashtable keys
ID
Color
Shape
Print all hashtable values
1
Blue
Square
Get ID
1
Get Shape
print Size
3
Add key-value
Add key-value
print Size
5
Remove key-value
print Size
4
sort by key

Name                           Value                                                                                                   
----                           -----                                                                                                   
Color                          Blue                                                                                                    
Created                        Now                                                                                                     
ID                             1                                                                                                       
Shape                          
Square    

Powershell – Regular Expression

A regular expression is a special sequence of characters that helps you match or find other strings or sets of strings, using a specialized syntax held in a pattern. They can be used to search, edit, or manipulate text and data.

Here is the table listing down all the regular expression metacharacter syntax available in PowerShell −

Here is a complete examples showing how to use regex in PowerShell;

Powershell – Backtick

Backtick (`) operator is also called word-wrap operator. It allows a command to be written in multiple lines. It can be used for new line (`n) or tab (`t) in sentences as well. See the examples below −

Example 1

Get-Service * | Sort-Object ServiceType `
| Format-Table Name, ServiceType, Status -AutoSize

It will become

Get-Service * | Sort-Object ServiceType | Format-Table Name, ServiceType, Status -AutoSize

Verify the output as

Name                                                   ServiceType  Status
----                                                   -----------  ------
MSSQLServerADHelper100                             Win32OwnProcess Stopped
ntrtscan                                           Win32OwnProcess Running
...

Example 2

Use of new line and tab.

> Write-host "Title Subtitle"
Title Subtitle

> Write-host "Title `nSubtitle"
Title 
Subtitle

> Write-host "Title `tSubtitle"
Title   Subtitle

Powershell – Brackets

Powershell supports three types of brackets.

• Parenthesis brackets. − ()

• Braces brackets. − {}

• Square brackets. − []

Parenthesis brackets

This type of brackets is used to

• pass arguments

• enclose multiple set of instructions

• resolve ambiguity

• create array

Example

> $array = @("item1", "item2", "item3")
 
> foreach ($element in $array) { $element }
item1
item2
item3

Braces brackets

This type of brackets is used to

• enclose statements

• block commands

Example

$x = 10

if($x -le 20){
   write-host("This is if statement")
}

This will produce the following result −

Output

This is if statement.

Square brackets

This type of brackets is used to

• access to array

• access to hashtables

• filter using regular expression

Example

> $array = @("item1", "item2", "item3")
 
> for($i = 0; $i -lt $array.length; $i++){ $array[$i] }
item1
item2
item3
 
>Get-Process [r-s]*
 Handles    NPM(K)     PM(K)    WS(K)   VM(M)   CPU(s)     Id    ProcessName
-------    ------     -----     -----   -----   ------     --    -----------  
    320        72     27300     33764    227     3.95    4028    SCNotification 
   2298        77     57792     48712    308             2884    SearchIndexer
   ...

Powershell – Alias

PowerShell alias is another name for the cmdlet or for any command element.

Creating Alias

Use New-Alias cmdlet to create a alias. In the below example, we”ve created an alias help for Get-Help cmdlet.

 New-Alias -Name help -Value Get-Help  

Now invoke the alias.

 help Get-WmiObject -Detailed  

You will see the following output.

NAME
   Get-WmiObject
    
SYNOPSIS
   Gets instances of Windows Management Instrumentation (WMI) classes or information about the available classes.    
    
SYNTAX
   Get-WmiObject [
...

Getting Alias

Use get-alias cmdlet to get all the alias present in current session of powershell.

 Get-Alias

You will see the following output.

CommandType     Name                     Definition
-----------     ----                     ----------  
Alias           %                        ForEach-Object
Alias           ?                        Where-Object
Alias           ac                       Add-Content
Alias           asnp                     Add-PSSnapIn 
...

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