Output whole line once for each unique value of a column (Bash)

Question

This must surely be a trivial task with awk or otherwise, but it\'s left me scratching my head this morning. I have a file with a format similar to this:

<

Answer 1

awk '{if($2==temp){next;}else{print}temp=$2}' your_file

tested below:

> awk '{if($2==temp){next;}else{print}temp=$2}' temp
pep> AEYTCVAETK         2       genes ADUm.1024,ADUm.5198,ADUm.750
pep> AIQLTGK            1       genes ADUm.1999,ADUm.3560
pep> KHEPPTEVDIEGR      5       genes ADUm.367
pep> VSSILEDKTT         9       genes ADUm.1192,ADUm.2731
pep> AIQLTGK            10      genes ADUm.1999,ADUm.3560
pep> VSSILEDKILSR       3       genes ADUm.2146,ADUm.5750