Hi
I want to uniq the content of a file based on 4th field
a.txt
abcd,123,456,234,asd
defg,123,456,235,asd
abcd,123,456,234,asd,lkjl,ijk
ijkl,123,456,234,asd
defg,123,456,235,asd,dfg,klm
o/p will be like
abcd,123,456,234,asd
defg,123,456,235,asd
ijkl,123,456,234,asd
or
abcd,123,456,234,asd,lkjl,ijk
ijkl,123,456,234,asd
defg,123,456,235,asd,dfg,klm
pls help