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:

line3
line2

The result should be :

line1
line4

I tried to use this command but it works only if I have one line in file2.txt :

Get-Content C:\file1.txt | Where-Object {$_ -notmatch $(get-content C:\file2.txt)}

Note : I don't want to compare 2 files to see if they are the same.

Any idea? I'm pretty new to powershell.

Use -in instead of -match, explained in the answers here of almost the same thing: stackoverflow.com/questions/39307707/… — TessellatingHeckler
– TessellatingHeckler, Commented Sep 5, 2016 at 22:09
BTW to learn PS faster, use PowerShell ISE where you can debug the code and press F1 on any keyword to view the built-in help (beware it's not as complete as online articles and sometimes it shows a list of matching topics in the console, in that case select one and press F1 again). — woxxom
– woxxom, Commented Sep 5, 2016 at 22:12

InteXX · Accepted Answer · 2019-07-24 00:07:47Z

6

Next code snippet shows two different ways to achieve the same result:

$filebefore="$env:TEMP\beforerestart.txt"    # change to match your circumstances
$file_after="$env:TEMP\after_restart.txt"    # ditto

### Compare-Object way
$array = Compare-Object $(Get-Content $filebefore) $(Get-Content $file_after)
$array | where {$_.SideIndicator -eq "<="} | 
              Format-Table -Property InputObject -AutoSize -HideTableHeaders

### -NotIn operator way
$(Get-Content $filebefore) | 
     Where-Object {$_ -notIn $(Get-Content $file_after)}

edited Jul 24, 2019 at 0:07

InteXX

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answered Sep 6, 2016 at 9:36

JosefZ

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3 Comments

timothepoznanski Over a year ago

the -NotIn way is the one for my case! Thanks! But it doesn't work when lines contain accent caracteres... Any hint ?

JosefZ Over a year ago

@Pozinux please read Get-Content for FileSystem, use appropriate value for -Encoding parameter.

timothepoznanski Over a year ago

Found the solution! Thanks so much for your quick anwser.

Joe DeMate · Accepted Answer · 2016-09-05 23:02:09Z

4

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

answered Sep 5, 2016 at 23:02

Joe DeMate

414 bronze badges

1 Comment

Amazon Dies In Darkness Over a year ago

I get the following error: Where-Object : Cannot bind argument to parameter 'FilterScript' because it is null. Any ideas?

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