Scripting in Windows Environments - kszk.sch.bme.hu · •cmd.exe – Windows NT •cscript.exe / wscript.exe – Windows 98 •Monad (2002) -> Windows PowerShell •1.0 (2006) –

PowerShell

Scripting in

Windows Environments 2016.04.03. Gergő Ládi ([email protected])

About Me

• MSc Student @ BUTE (BME)

• Member of KSZK since 2011

• Relevant certifications:

2016.04.03. Gergő Ládi ([email protected]) 2

Outline

• What is PowerShell? • Versions

• Features

• Scripting in PowerShell • PowerShell 101: cmdlets, aliases, comments, variables, (using) operators, control structures, working with files

• Advanced scripting: functions of your own, custom aliases, using .NET classes, loading dynamic code PSProviders & PSDrives, remoting, package management


CLIs in 2016 :O ?!

2016.04.03. Gergő Ládi ([email protected])

CLIs in 2016 :O ?!

• One might be tempted to think that Command Line Interfaces are a thing of the past…

• Both GUIs and CLIs have their own strengths and weaknesses • CLIs are more efficient, …

• Less RAM, CPU, disk usage • Operations usually take less time to perform • Possibility of automation

• … but have a steeper learning curve • Unusual, confusing at first • Tens (hundreds) of commands with different syntaxes • Feedback: less, later


What is PowerShell?


A bit of history

• COMMAND.COM – MS-DOS

• cmd.exe – Windows NT

• cscript.exe / wscript.exe – Windows 98

• Monad (2002) -> Windows PowerShell

• 1.0 (2006) – XP SP2, Server 2003, Vista, (WS 2008) • 2.0 (2009) – Windows 7, Windows Server 2008 R2

• 3.0 (2011) – Windows 8, Windows Server 2012

• 4.0 (2013) – Windows 8.1, Windows Server 2012 R2

• 5.0 (2015) – Windows 10, Windows Server 2016


Notable features

• Object oriented (1.0)

• Modular (2.0)

• PowerShell Remoting (2.0, 3.0)

• Integrated Scripting Environment (2.0, 3.0)

• Supports debugging (breakpoints) (2.0)

• Asynchronous operations (2.0)

• Transactions (2.0)

• Desired State Configuration support (4.0, 5.0)

• Package management support (5.0)

• Syntax highlighting inside the command line (5.0)


Where is PowerShell used?

• Windows client operating systems • App-V

• Windows server operating systems • Active Directory

• Microsoft Exchange

• Skype for Business (formerly Lync)

• Computer viruses • CryptoWall, POSHCODER


PowerShell 101


PS 101 - Cmdlets

• Cmdlet: a command that performs operations • Not a separate executable

• May take input from the pipeline and may have an input parameter list

• Has the form Verb-Noun • Get-Help

• Get-Help Get-Command

• Get-Help Get-ChildItem –Examples

• Remove-Item C:\Windows\notepad.exe -WhatIf

• Get-ChildItem -File -Path "C:\Windows" | Select-Object Name, Length | Sort-Object -Descending Length


PS 101 - Aliases

• Alias: a shortcut that invokes a different command (usually one of a longer name) • gci, ls, dir -> Get-ChildItem

• del, rm -> Remove-Item

• cat, gc -> Get-Content

• gh, man -> Get-Help

• To list all available aliases • Get-Alias


PS 101 - Comments

• Comment: line(s) that are not meant to be interpreted by the parser, but convey information to the (other) programmers • # This is a comment. • <# This is a multi-line comment #>

• Get-Help Get-ChildItem # This is an in-line comment.


PS 101 - Variables

• Variable: a language construct that can be used to store values • Must begin with the $ sign, e.g. $MyVariable

• Working with variables • $Name = "Jonathan" # String

• $Age = 42 # Integer

• $Hobbies = @("Eating", "Sleeping", "F......") # Array • $John = @{ Name = $Name; Age = $Age; Hobbies = $Hobbies } # Hash

• $UserDirContents = Get-ChildItem -Path "C:\Users\$Name"


PS 101 - Variables

• Working with variables (cont'd) • Write-Host "$Name is $Age years old." # Will be substituted

• Write-Host '$Name is $Age years old.' # Won't be substituted

• Write-Host "Next year, he'll be $($Age + 1)" # In-line eval.

• Write-Host "$($John.Name) is a nice guy." # Accessing a member

• write-host "$NAME FOR PRESIDENT!" # Cmdlet and variable names are case-INsensitive


PS 101 – Operators

• -lt, -le, -gt, -ge : <, <=, >, >=

• -eq, -ne : ==, !=

• -band, -bor, -bxor, -bnot : bitwise operators

• -contains, -notcontains

• -like, -notlike, -match, -notmatch


PS 101 – Using operators

• Using comparison operators • $Age -lt 18

• $Name -eq "jonathan"

• $Name -ceq "jonathan"

• $Hobbies -contains "Eating"

• $Name -like "Jo?ath*"

• "1970.01.01. Epoch" -match "\d{4}\.[0-9]{1,2}\.\d{1,2}\. [a-zA-Z]*"


PS 101 - Control structures

• Control structure: a structure that analyses state information and changes the execution path based on this • If, If-Else, If-ElseIf-Else, For, ForEach, While, …

• Examples If ($John.Age -lt 18) {

Write-Host "John is under 18!" } ElseIf ($John.Age -eq 18) { Write-Host "John is exactly 18!" } Else { Write-Host "John is over 18! }



For ($i = 0; $i -lt 60; ++$i) {

Write-Host $i

Start-Sleep –Milliseconds 100

}

ForEach ($Hobby in $Hobbies) {

Write-Host "John likes $Hobby"

}



Write-Host "Starting countdown!"

$i = 10

While ($i –gt 0) {

Write-Host ($i--)

Start-Sleep -Milliseconds 100

}

Write-Host "Done."


PS 101 – Working with files

• $Hobbies | Out-File "JohnsHobbies.txt"

• $Contents = Get-Content JohnsHobbies.txt # Quotes can be omitted

• $UserDirContents | Export-Csv JohnsFiles.csv

• $ImportedData = Import-Csv JohnsFiles.csv


PowerShell 201


PS 201 – Functions of your own

• Function: a block of code that can be called multiple times Function Touch-File($File) { If (Test-Path -Path $File) { (Get-ChildItem -Path $File).LastWriteTime = [System.DateTime]::Now } Else { New-Item -Path $File | Out-Null } }


PS 201 – Aliases, $PROFILE

• New-Alias -Name touch -Value Touch-File

• touch MyFile.txt # is equivalent to Touch-File –File MyFile.txt

• $PROFILE: a script that is executed each time a shell is opened • Add custom function declarations and aliases here to make them permanent


PS 201 – Using .NET classes

• It is possible to use any BCL classes from the respective .NET Framework version

• You can also load classes from an external assembly

• … or compile code on-the-fly

• $Date = [System.DateTime]::Now



$TcpClient = New-Object System.Net.Sockets.TcpClient

$TcpClient.Connect("max.sch.bme.hu", 25)

$TcpClient.ReceiveTimeout = 5000

$Buffer = New-Object Byte[] 1024

$Recvd = $TcpClient.Client.Receive($Buffer)

Write-Host ([System.Text.Encoding]::ASCII).GetString($Buffer, 0, $Recvd)



$DataToSend = "EHLO" + [Environment]::NewLine

$Buffer = [System.Text.Encoding]::ASCII.GetBytes($DataToSend) $TcpClient.Client.Send($Buffer) | Out-Null

$Buffer = New-Object Byte[] 1024

$Recvd = $TcpClient.Client.Receive($Buffer)

Write-Host ([System.Text.Encoding]::ASCII).GetString($Buffer, 0, $Recvd)

$TcpClient.Close()


PS 201 – Loading dynamic code

$MyDynamicCode = @"

namespace MyNamespace {

public static class MyClass {

public static int MyFunction(int i){

return 42 – 2*i;

}

}

}

"@

Add-Type –TypeDefinition $MyDynamicCode –Language Csharp

[MyNamespace.MyClass]::MyFunction(10) # Returns 22


PS 201 – PSProviders & PSDrives

• Get-PSProvider

• Get-PSDrive

• cd Variable:

• ls

• cd HKCU:

• New-Item -Name "MyKey" -ItemType DWORD -Value 42


PS 201 – PowerShell remoting

• Enter-PSSession -ComputerName remoteapp

• whoami

• hostname


PS 201 – Package management

• Install-Package -Provider bootstrap chocolatey

• Get-PackageProvider -Name chocolatey

• Install-Package vlc


Recommended homework

• Write a PowerShell script that calculates the size of each user's home folder then writes the results to a file, sorted by the total size occupied. Home folders having a size of less than 10 MBs should not appear on the list.

• Write a PowerShell function that takes a web site URL as a parameter and returns a list of all external JavaScript files on that site.


Sources

• Mastering PowerShell (Dr. Tobias Weltner)

• Windows PowerShell 3.0 Step by Step (Ed Wilson)

• PowerShell Magazine (http://www.powershellmagazine.com)

• Microsoft Developer Network (https://msdn.microsoft.com/en-us/default.aspx)

• Wikipedia (https://en.wikipedia.org)


https://msdn.microsoft.com/en-us/default.aspx



Thank you for your attention!


Q & A


Documents

Scripting in Windows Environments - kszk.sch.bme.hu · •cmd.exe – Windows NT •cscript.exe / wscript.exe – Windows 98 •Monad (2002) -> Windows PowerShell •1.0 (2006) –