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