tiger bear fountain house bear kitchen peanuts headphone car
Now, we only care about whether or not a field has appeared or not. If bear appears twice, we don't care, we just want to know that it has occurred.
The way in which we can do this is using awk.
awk '!x[$2]++' test tiger bear fountain peanuts headphone car
We can see that we that it has gone through and looked for whether or not the second column has occurred more than once and removes occurrences that exist more than once.
The method in which awk achieves this is explained in the following: http://stackoverflow.com/questions/10842118/explain-this-duplicate-line-removing-order-retaining-one-line-awk-command