I have a large CSV file and want to empty certain columns if they were seen before.So I have (to illustrate my problem):Category | Subcategory---------+------------foo      | barfoo      | barfoo      | foobarfoo      | foobarAnd I want: Category | Subcategory---------+------------foo      | bar         |          | foobar         |The whole CSV is sorted (with sort --strong -k 1,2), so I just need a way to do my task with one column and can later use the same method with the other column.Basically: delete every occurence of foo except the first.It is similar to this question, but I don't want to remove the complete line ..I'm not sure how to do this, since I'm not that into awk.Can anyone help me?
Empty columns which were seen before
awk;macintosh;csv