1. PowerShell for Developers
Ing. Ondřej Ševeček | GOPAS a.s. |
MCM: Directory Services | MVP: Enterprise Security | Certified Ethical Hacker |
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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 Version 2 Version 3 Version 4
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}
(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
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 (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 = 'zkusebni retezec' $nameBytes = [System.Text.ASCIIEncoding]::ASCII.GetBytes($name) $sha = New-Object System.Security.Cryptography.SHA1CryptoServiceProvider $hashBytes = $sha.ComputeHash($nameBytes) # bytes array (20 bytes as SHA-1 is always 160bits) $hashBytes # the same in Base64 [Convert]::ToBase64String($hashBytes) # the same 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 namespace Sevecek { public class CookieAwareWebClient : System.Net.WebClient { private System.Net.CookieContainer cookieContainer = new System.Net.CookieContainer(); protected override System.Net.WebRequest GetWebRequest(System.Uri address) System.Net.WebRequest baseRequest = base.GetWebRequest(address); if (baseRequest is System.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 struct subStruct { public string name; public int age; } public struct parentStruct { 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

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

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