delete lines that contain duplicated column items
I have a simple txt file, like:
...
a a
aa a
b b
ba b
...
I want to just keep the lines that first appeared in column 2 and delete the follow lines that contain duplicated ones in column 2.
then it will like:
...
a a
b b
...
I've tried `uniq -f1` but it didn't work.
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