Sort and remove duplicates based on column

Question

I have a text file:

$ cat text
542,8,1,418,1
542,9,1,418,1
301,34,1,689070,1
542,9,1,418,1
199,7,1,419,10

I\'d like to sort the file based on

Answer 1

When sorting on a key, you must provide the end of the key as well, otherwise sort uses all following keys as well.

The following should work:

sort -t, -u -k1,1n text

Answer 2

The problem is that when you provide a key to sort the unique occurrences are looked for that particular field. Since the line 542,8,1,418,1 is displayed, sort sees the next two lines starting with 542 as duplicate and filters them out.

Your best bet would be to either sort all columns:

sort -t, -nk1,1 -nk2,2 -nk3,3 -nk4,4 -nk5,5 -u text

or

use awk to filter duplicate lines and pipe it to sort.

awk '!_[$0]++' text | sort -t, -nk1,1