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PowerShell for Developers

PowerShell for Developers. Ing. Ondřej Ševeček | GOPAS a.s. | MCM: Directory Services | MVP: Enterprise Security | Certified Ethical Hacker | ondrej@sevecek.com | www.sevecek.com |. GOPAS: info@gopas,cz | www.gopas.cz | www.facebook.com/P.S.GOPAS. Why the admins use PowerShell.

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PowerShell for Developers

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  1. PowerShell for Developers Ing. Ondřej Ševeček | GOPAS a.s. | MCM: Directory Services | MVP: Enterprise Security | Certified Ethical Hacker | ondrej@sevecek.com | www.sevecek.com | GOPAS: info@gopas,cz| www.gopas.cz | www.facebook.com/P.S.GOPAS

  2. Why the admins use PowerShell • Newer command line marketing • older VBScript still supported but with limited functionality • Script from command line or textual .PS1 files • extensive object oriented pipeline • support for CMD, EXE, D/COM, NET (plus Win32API through PINVOKE)

  3. Why developers might be interested • Provide Admins with familiar interface for custom applications • own cmdlets in NET • Automate own tasks • builds, file distribution, signing, packaging etc. • Develop installation tasks • MSIEXEC custom actions - external • Test / validate / proof of concept • which is non-compiled, quickly written

  4. PowerShell versions • Version 1 • download for Windows XP and 2003 and Vista • built into Windows 2008 • Version 2 • download for Windows XP and 2003, Vista, 2008 • built into Windows 7 and 2008 R2 • NetFx 2.0 CLR • Version 3 • download for Windows 7 and 2008 R2 • built into Windows 8 and 2012 • NetFx 4.0 CLR • Version 4 • download for Windows 7 and 2008 R2, 8 and 2012 • built into Windows 8.1 and 2012 R2 • NetFx 4.5 CLR • Download as Windows Management Framework

  5. Determine version • $psVersionTable • Get-Host • powershell -v 2, powershell -v 3

  6. Script development environment • Notepad • PowerShell ISE • third-party free download • not necessary anymore since Windows 8

  7. Basic language elements • Variables, values and constants • $true, $false, 0x38B, $null • 'string', "string", {code} • @(array), @{hash}, (1..30) • Types (objects vs. structs) • Operators • -eq/-ceq, -ge/-gt, -le/-lt, -like, -clike, -match, -cmatch, -join, -split, -f, -is • -and, -or, -not, !, -xor, -band, -bor, -not, -bxor • *, /, % • Conditions • While, Do While, Foreach, break, continue • Switch • Functions

  8. String and Date methods • [String] • ToLower() • ToUpper() • Split() • Trim() • [DateTime] • AddDays() • Parse()

  9. Object wrappers (adapters) • Get-Member • .psbase, .psadapted, .psextended, .psobject • Get-Process, [XML]

  10. Weird access to non-existing members • .NonExistentProperty - no efect, empty • .NonExistentMethod() - exception • $array[outsideIndex] - exception

  11. Example: Object pipe Get-Process, Stop-Process New-Object System.DirectoryServices.DirectoryEntry New-Object System.DirectoryServices.DirectorySearcher [System.Collections.ArrayList] [System.Collections.Hashtable]

  12. Example: COM objects $word = New-Object -ComObject 'Word.Application' $doc = $word.Documents.Add() $range = $doc.Range() $range.Font.Size= 20 $range.Font.Name= 'Verdana' $range.ParagraphFormat.Alignment= 2 $range.Text = 'Hellow world' $docName = 'c:\public\hello.docx' $doc.SaveAs([ref] $docName) $word.Quit()

  13. Example: Static methods and properties • [System.Text.ASCIIEncoding]::ASCII.GetBytes() • [System.Math]::PI, [Math]::Round() • [Convert]::ToBase64String(), [BitConverter]::ToString()

  14. Type accelerators • [ADSI] • [WMICLASS] • [XML]

  15. Custom objects • New-Object PSCustomObject • Add-Member

  16. Weird array comparisons @(5, 3, 2, 8, 11) -gt 6 @(5, (Get-Date), $null, 2, $null, 11) -ne $null

  17. Weir parameter parsing • Parsing in command mode • everything is string except for variables and things in parenthesis • watch out for array goes just with comma separator , • Parsing in expression mode • First token switches the mode: • letter, &, .<letter>, .<space> • number, variable, quoted string

  18. Weird default values and conversions • [string] $nothing = $null • [int] $noNumber = $null • [StringBuilder] $noStrBuilder = $null • [int] '55' • '38' * 3 • '38' + '95' • 95 + '11' • [string] (Get-Process) • Get-Process | fl * | Out-String

  19. Weird collection member functions • PowerShell 3 and newer • If the member does not exist in the collection itself, it gets called on all members

  20. Weird function return values • Whatever goes to pipe in function is returned in array • If you return single-item array it gets converted into a single object • If you return [ArrayList], it converts to [Object[]]

  21. Example: SHA1 $name = 'zkusebniretezec' $nameBytes = [System.Text.ASCIIEncoding]::ASCII.GetBytes($name) $sha = New-Object System.Security.Cryptography.SHA1CryptoServiceProvider $hashBytes = $sha.ComputeHash($nameBytes) # bytesarray (20 bytes as SHA-1 isalways 160bits) $hashBytes # thesame in Base64 [Convert]::ToBase64String($hashBytes) # thesame in Hex [BitConverter]::ToString($hashBytes)

  22. C# from PowerShell • Here strings • start @" at the end of a line • end as the first character on an empty line "@ Add-Type -TypeDefinition $hereStringDef Add-Type -AssemblyName 'My.Assembly.Name' Add-Type -Path 'c:\projects\myassemblyname.dll' [System.Reflection.Assembly]::LoadFile('…')

  23. Example: Cookie-aware WebClient $typeCookieAwareWebClient = @" namespaceSevecek { public classCookieAwareWebClient : System.Net.WebClient { privateSystem.Net.CookieContainercookieContainer = newSystem.Net.CookieContainer(); protectedoverrideSystem.Net.WebRequestGetWebRequest(System.Uriaddress) { System.Net.WebRequestbaseRequest = base.GetWebRequest(address); if (baseRequestisSystem.Net.HttpWebRequest) { (baseRequest as System.Net.HttpWebRequest).CookieContainer = cookieContainer; } return baseRequest; } } } "@ if (-not ('Sevecek.CookieAwareWebClient' -as [type])) { Add-Type -TypeDefinition $typeCookieAwareWebClient }

  24. Weird struct assignment $structs = @" namespace Sevecek { public structsubStruct { public string name; public int age; } public structparentStruct { public string id; public subStruct person; } } "@ Add-Type -TypeDefinition $structs $onePerson = New-Object parentStruct $onePerson.person.name = 'ondrej' $onePerson.person

  25. Exception handling try { throw } catch [type] {} finally {} $error -ErrorAction $errorActionPreference throw 'some error' throw (Get-Process)[5]

  26. Win32API with PINVOKE • www.pinvoke.net

  27. Custom CMDLETs in C# • using System.Management.Automation • Class for each cmdlet - decorated as cmdlet • Public properties as parameters - decorated again • Override void processing methods • WriteObject() to pipeline • http://msdn.microsoft.com/en-us/library/dd878294(v=vs.85).aspx

  28. NASHLEDANOU nakurzech v počítačové škole GOPAS, a.s. GOPAS: info@gopas,cz| www.gopas.cz | www.facebook.com/P.S.GOPAS

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