Powershell Hints & Tricks

Powershell-Hints.md

Powershell Hints & Tricks

Convert hex to bytes, bytes to hex

function ConvertTo-Hex([byte[]]$bytes)
{
    return ($bytes | % { $_.ToString("X2") }) -join ""
}

function ConvertTo-Bytes([string]$hex)
{
    return $hex -split "(?<=\G\w{2})(?=\w{2})" | % { [Convert]::ToByte( $_, 16 ) }
}

How to owerride default output

$LOGFILE = "c:\my.log"

function global:Out-Default 
{
    process 
    {
        "$(get-date -Format s) [$PID] $_" | out-file -FilePath $LOGFILE -Append -Force; $_ | out-host;
    }
}

Get (or search across) list of registered COM objects

function Search-COM( $filter = "*")
{
    return Get-ChildItem HKLM:\Software\Classes -ErrorAction SilentlyContinue | 
        ? { $_.PSChildName -match '^\w+\.\w+$' `
                           -and (Test-Path -Path "$($_.PSPath)\CLSID") `
                           -and $_.PSChildName -like $search_filter } | Select-Object -ExpandProperty PSChildName 
}

New-Object -Com (Search-COM("wscript.network")) | Get-Member

Retry (simple)

function retry( $times, $sleep, $script )
{
    0..($times - 1) | 
    % { & { 
            write-host -nonewline (get-date).tolongtimestring()" "
            try     { & $script       } 
            catch   { $_.Exception    } 
            finally { sleep -s $sleep } 
          }
      }
}
#usage: check google.com every 1 m in 24h:
retry (60*24) 60 { (Invoke-WebRequest "https://google.com").statusCode } 

Allow connect to untrusted SSL

Add-Type -TypeDefinition "
using System.Net;using System.Security.Cryptography.X509Certificates;
public class AllowConnectToUntrustedSSL : ICertificatePolicy {
    public bool CheckValidationResult(ServicePoint srvPoint, X509Certificate certificate, WebRequest request, int certificateProblem) { return true; }
}"
[System.Net.ServicePointManager]::CertificatePolicy = New-Object AllowConnectToUntrustedSSL

Get lengths of files

$dir = "C:\path\"
Get-ChildItem -Path $dir -Recurse -Filter "*.cs" |
% {
    Write-Host  "$($_.Name) - $((Get-Content $_.FullName).Length)"
  }

Protect/Unprotect data

$stroke = "After this stroke will protected, only current user could unprotect this stroke back."
$output = "C:\Temp\data.ecrypted"
$salt = "s a l t"

$DP = [System.Security.Cryptography.ProtectedData]
$scope = [System.Security.Cryptography.DataProtectionScope]::CurrentUser
$ENC = [System.Text.Encoding]::UTF8

sc $output -Value $DP::Protect($ENC.GetBytes($stroke), $ENC.GetBytes($salt), $scope) -Force

$unprotected = $ENC.GetString( $DP::Unprotect( (gc $output), $ENC.GetBytes($salt), $scope) )

if( $unprotected -ne $stroke ){
    throw "Unprotect check failed: protected data cannot be restored"}

Update ENV path valiable

$env:Path = [System.Environment]::GetEnvironmentVariable("Path","Machine") + ";" + [System.Environment]::GetEnvironmentVariable("Path","User")

Unixtime

get-date -uformat %s
# 1465571078,24586

((get-date -uformat %s) -split ',')[0]
# 1465571078

$date = [DateTime]::Now.AddYears(1)
get-date($date) -uformat %s

Create Hashtable Dynamicaly

$Field1 = "1"
$Field2 = "2"
$Field3 = "3"
$Field4 = "4"
$Field5 = "5"
$Field6 = "6"
$Field7 = "7"

$data = @{}
"a,b,c,d,e,f" -split "," | % {$n=0} {
    $n++
    $data.Add($_, ((Get-Variable -Name "Field$n").Value) )
}

$data

Generate self-signed Certificate

$certName = "my-self-signed-certificate"
$certPass = "SuperPassword"
$outputFolder = (Split-Path $PSCommandPath -Parent)

$cert = New-SelfSignedCertificate -DnsName "Windows Azure Tools" -CertStoreLocation "cert:\LocalMachine\My"
$password = ConvertTo-SecureString -String $certPass -Force -AsPlainText
Export-PfxCertificate -Cert $cert -FilePath "$outputFolder\$certName.pfx" -Password $password
Export-Certificate -Cert $cert -Type CERT -FilePath "$outputFolder\$certName.cer"