Remove lines from file1 that exist in file2 in Powershell

Question

I have a file1.txt which contains:

line1
line2
line3
line4

I want to remove from file1.txt all the lines which exist in another file2.txt:

Answer 1

Compare-Object is good for getting the difference between two files. Here is some sample code to accomplish what you have asked.

$file1 = Get-Content C:\temp\file1.txt
$file2 = Get-Content C:\temp\file2.txt
$Diff = Compare-Object $File1 $File2
$LeftSide = ($Diff | Where-Object $_.SideIndicator -eq '<=').InputObject
$LeftSide | Set-Content C:\temp\file3.txt