Powershell

Windows PowerShell is a command-line shell and scripting language designed for system administration.

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.

Create a script

• Create a example.ps1 script:

  <#
  .SYNOPSIS
  	Example PowerShell script
  
  .DESCRIPTION
  	Demonstrates variables, input/output, conditions, loops, and file I/O.
  
  .AUTHOR
  	Your Name
  
  .DATE
  	2026-01-15
  #>
  
  ...

• Allow script execution (once)

  Set-ExecutionPolicy -ExecutionPolicy RemoteSigned -Scope CurrentUser

• Run the script

  .\example.ps1

Cmdlet

Powershell commands are called cmdlets:

• 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.

Syntax

<Verb>-<Name>

Common verbs to use include:

• Get

• Start

• Stop

• Read

• Write

• New

• Out

Comments

# Comment

Variables

• Create variable:

  $variable_name = <value>

• Use variable:

  $variable_name

• Get information (e.g. properties and methods) about a variable:

  $variable_name | Get-Member

Example:

Special variables

Operator	Description
$$	Represents the last token in the last line received by the session.
$?	Represents the execution status of the last operation. It contains TRUE if the last operation succeeded and FALSE if it failed.
$^	Represents the first token in the last line received by the session.
$_	Same as $PSItem. Contains the current object in the pipeline object. You can use this variable in commands that perform an action on every object or on selected objects in a pipeline.
$ARGS	Represents an array of the undeclared parameters and/or parameter values that are passed to a function, script, or script block.
$CONSOLEFILENAME	Represents the path of the console file (.psc1) that was most recently used in the session.
$ERROR	Represents an array of error objects that represent the most recent errors.
$EVENT	Represents a PSEventArgs object that represents the event that is being processed.
$EVENTARGS	Represents an object that represents the first event argument that derives from EventArgs of the event that is being processed.
$EVENTSUBSCRIBER	Represents a PSEventSubscriber object that represents the event subscriber of the event that is being processed.
$EXECUTIONCONTEXT	Represents an EngineIntrinsics object that represents the execution context of the PowerShell host.
$FALSE	Represents FALSE. You can use this variable to represent FALSE in commands and scripts instead of using the string "false".
$FOREACH	Represents the enumerator (not the resulting values) of a ForEach loop. You can use the properties and methods of enumerators on the value of the $ForEach variable.
$HOME	Represents the full path of the user's home directory.
$HOST	Represents an object that represents the current host application for PowerShell.
$INPUT	Represents an enumerator that enumerates all input that is passed to a function.
$LASTEXITCODE	Represents the exit code of the last Windows-based program that was run.
$MATCHES	The $Matches variable works with the -match and -notmatch operators.
$MYINVOCATION	$MyInvocation is populated only for scripts, function, and script blocks. PSScriptRoot and PSCommandPath properties of the $MyInvocation automatic variable contain information about the invoker or calling script, not the current script.
$NESTEDPROMPTLEVEL	Represents the current prompt level.
$NULL	$null is an automatic variable that contains a NULL or empty value. You can use this variable to represent an absent or undefined value in commands and scripts.
$PID	Represents the process identifier (PID) of the process that is hosting the current PowerShell session.
$PROFILE	Represents the full path of the PowerShell profile for the current user and the current host application.
$PSCMDLET	Represents an object that represents the cmdlet or advanced function that is being run.
$PSCOMMANDPATH	Represents the full path and file name of the script that is being run.
$PSCULTURE	Represents the name of the culture currently in use in the operating system.
$PSDEBUGCONTEXT	While debugging, this variable contains information about the debugging environment. Otherwise, it contains a NULL value.
$PSHOME	Represents the full path of the installation directory for PowerShell.
$PSITEM	Same as $_. Contains the current object in the pipeline object.
$PSSCRIPTROOT	Represents the directory from which a script is being run.
$PSSENDERINFO	Represents information about the user who started the PSSession, including the user identity and the time zone of the originating computer.
$PSUICULTURE	Represents the name of the user interface (UI) culture that is currently in use in the operating system.
$PSVERSIONTABLE	Represents a read-only hash table that displays details about the version of PowerShell that is running in the current session.
$SENDER	Represents the object that generated this event.
$SHELLID	Represents the identifier of the current shell.
$STACKTRACE	Represents a stack trace for the most recent error.
$THIS	In a script block that defines a script property or script method, the $This variable refers to the object that is being extended.
$TRUE	Represents TRUE. You can use this variable to represent TRUE in commands and scripts.

Array

• Declare an array:

  $<array_name> = <value1>, <value2>, <valueN>

  or

  $<array_name> = <value1>..<valueN>

  or

  $<array_name> = @(<value1>..<valueN>)

• Length of the array:

  $<array_name>.length

Examples:

$mylist1 = 3.5, 4.8, 5, 10
$mylist2 = 1..4
$mylist3 = @(0..4)

Hashtables

• Declare a hashtable

  $<hashtable_name> = @{ <key1> = <value1>; <key2> = <value2>; <keyN> = <valueN>}

  or

  $<hashtable_name> = @{}

• Access a value

  $<hashtable_name>["<key>"]

Examples:

• Return keys array:

  $<hashtable_name>.keys

• Return

  $<hashtable_name>.values

Examples:

Operators

Arithmetic Operators

Operator	Description	Example
+	Addition	A + B
-	Subtraction	A - B
*	Multiplication	A * B
/	Division	B / A
%	Modulus	B % A

Comparison Operators

Operator	Description	Example
eq	equals	A -eq B
ne	not equals	A -ne B
gt	greater than	B -gt A
ge	greater than or equals to	B -ge A
lt	less than	B -lt A
le	less than or equals to	B -le A

Assignment Operators

Operator	Description	Example
=	Simple assignment operator. Assigns values from right side operands to left side operand.	C = A + B
+=	Add AND assignment operator. It adds right operand to the left operand and assign the result to left operand.	C += A
-=	Subtract AND assignment operator. It subtracts right operand from the left operand and assign the result to left operand.	C -= A

Logical Operators

Operator	Description	Example
AND	logical and	(A -AND B)
OR	logical or	(A -OR B)
NOT	logical not	-NOT(A -AND B)

Condition statements

If Else

if(Boolean_expression) {
	#Statement 1
}else {
	#Statement 2
}

Switch case

switch(<test-value>) 
{
	<condition1> {<action1>}
	break;
	<condition2> {<action2>}
	break;
	<condition3> {<action3>}
	break;
}

Loops

For

for(<init>; <condition>; <increment>)
{
	#Statement
}

Example:

For each

foreach ($x in $<arrayname)
{ 
	#Statement
}

Example:

While

while(<condition>){
	#Statement
}

Example:

Do While

do {
	#Statement
} while(<condition>)

Example:

Write/read on console

Write on console

• Print <string> on console:

Write-Host <string>

• Print <string> on console without \n at the end:

Write-Host <string> -NoNewLine

Example:

Read input on console

• Read the value <variable_name> from user:

  $<variable_name> = Read-Host <string_for_user>

• Read the value <variable_name> from user:

  $<variable_name> = Read-Host <string_for_user> -AsSecureString

  As a value is being entered, asterisks (*) appear on the console in place of the input. When the Enter key is pressed, the value is stored as a SecureString object in the $<variable_name> variable.

Examples:

Common cmdlets

Help

Cmdlet	Description
Get-Help	Help about a command and its parameter
Get-Command	List all the commands

Updates

Cmdlet	Description
Get-HotFix	Get the list of available updates
Get-HotFix -id <id_num>	Check for missing or required KB with id <id_num>

Files and Folder Operations

Cmdlet	Description
New-Item -Path <dir_path> -ItemType Directory	Create a folder
New-Item -Path <file_path> -ItemType File	Create a file
Copy-Item <old_dir> <new_dir>	Copy a folder
Copy-Item <old_dir> -Destination <new_dir>	Copy a folder recursively
Copy-Item <old_file> <new_file>	Copy a file
Copy-Item -Filter <regex> -Path <old_path> -Recurse -Destination <new_path>	Copy all files matching a regex
Remove-Item <dir_file_path>	Delete a file/folder
Remove-Item <dir_path> -Recurse	Delete a folder recursively
Move-Item <old_path> <new_path>	Move a file
Rename-Item <old_path> <new_path>	Rename a file/folder
Test-Path <file_dir_path>	Check file/folder existence

Date and Time Operations

Cmdlet	Description
Get-Date	Print date and time
Get-Date -DisplayHint Date	Print only Date
Get-Date -DisplayHint Time	Print only Time
Set-Date -Date (Get-Date).AddDays(X)	Add X days, where X integer (remove X days if X negative), to current date

Files I/O

Cmdlet	Description
Get-Content <file_path>	Get file content of a file
(Get-Content <file_path>).length	Get number of character in a file
Set-Content <file_path> <new_content>	Set file content
Get-FileHash -Algorithm <hash_type> <file_path>	Get hash of a file (e.g. Get-FileHash -Algorithm SHA256 test.txt)

Download files

Invoke-WebRequest <URL> -OutputFile <file_path>

Cmdlets Output format

Cmdlet	Description
Format-List	Obtain more information about objects
findstr <string>	Grep results
Format-Table <column_name>	Keep only some columns of a table
Out-File <file_path>	Save the output to file <file_path>