How to remove lines from File A that are in File B using Windows powershell

Question

This other question is excellent for joining two files. I need to do sort of the opposite. I need to remove lines from File A that are in File B, using powershell.

This question is similar to this other question, except that question is for unix and this is for Windows 7 powershell.

The files are hosts files. Each one has lines consisting of:

• 127.0.0.1 host.domain.com

or

• 0.0.0.0 host.domain.com

or

• # this is a comment

Files may have up to 200,000 lines. Spaces and tabs may be present.

Although I prefer it to be preserved, order does not effect function.

Here are some examples of hosts files:

• https://adaway.org/hosts.txt
• https://pgl.yoyo.org/adservers/serverlist.php?hostformat=hosts&showintro=0&mimetype=plaintext
• https://raw.githubusercontent.com/StevenBlack/hosts/master/hosts
• https://hosts-file.net/ad_servers.txt
• http://winhelp2002.mvps.org/hosts.txt
• http://someonewhocares.org/hosts/hosts

(Don't worry about 0.0.0.0 vs 127.0.0.1 for this question.)

Answer 1

You can try this snippet:

$in1And2 = Compare-Object -ReferenceObject $file1 -DifferenceObject $file2 -PassThru -IncludeEqual -ExcludeDifferent