Compare 2 files and remove any lines in file2 when they match values found in file1

Question

I have two files. i am trying to remove any lines in file2 when they match values found in file1. One file has a listing like so:

File1

ZNI008
ZNI009         


        

Answer 1

this is using Bash and GNU sed because of the -i switch

cp file2 file3
while read -r; do
    sed -i "/$REPLY/d" file3
done < file1

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there is surely a better way but here's a hack around -i :D

cp file2 file3
while read -r; do
    (rm file3; sed "/$REPLY/d" > file3) < file3
done < file1

this exploits shell evaluation order

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alright, I guess the correct way with this idea is using ed. This should be POSIX too.

cp file2 file3
while read -r line; do
    ed file3 <

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in any case, grep seems to do be the right tool for the job.
@byrondrossos answer should work for you well ;)