how to sort based on a column but uniq based on another column?

Question

He all, I have a file having some columns. I would like to do sort for column 2 then apply uniq for column 1. I found this post talking about sort and uniq for the same column but my problem is a little bit different. I am thinking of using something using sort and uniq but don't know how. Thanks.

Answer 1

You can use pipe, however it's not in place.

Example :

$ cat initial.txt
1,3,4
2,3,1
1,2,3
2,3,4
1,4,1
3,1,3
4,2,4

$ cat initial.txt | sort -u -t, -k1,1 | sort -t, -k2,2
3,1,3
4,2,4
1,3,4
2,3,1

Result is sorted by key 2, unique by key 1. note that result is displayed on the console, if you want it in a file, just use a redirect (> newFiletxt)

Other solution for this kind of more complex operation is to rely on another tool (depending on your preferences (and age), awk, perl or python)

EDIT: If i understood correctly the new requirement, it's sorted by colum 2, column 1 is unique for a given column 2:

$ cat initial.txt | sort -u -t, -k1,2 | sort -t, -k2,2
3,1,3
1,2,3
4,2,4
1,3,4
2,3,1
1,4,1

Is it what you expect ? Otherwise, I did not understand :-)