This question already has an answer here:
Basically, I had a file, which contained around 90 usernames.
I had to delete all of those usernames from the passwd file, which was a total of 300 lines long.
I tried to come up with a way to at least filter the duplicate usernames and print out the ones, which have to remain but had no sucess.
Let's say that the file, where I had the 90 usernames for removal contains:
user1 user2 user3 user4
The passwd file contains these usernames, along with a lot more
user31 user32 user1 user23 user2 user4 user15 user3
The usernames inside the passwd file were randomly spread inside the file, so
diff -y wouldn't have done the job.
My goal here was to compare the two file, for example cat the file.txt and use the output to search inside the passwd. The result should be either a removal of the duplicate lines, or a printing of the unique lines.