bash - Get first N occurances of uniq lines, not only one -

i have file rows 2 fields separated whitespace:

fielda fieldx fieldb fieldx fieldc fieldx fieldd fieldx fielde fieldx fielda fieldy fieldb fieldy fieldc fieldy 

i need first n rows of type in second column. sort -k2 | uniq -f1 --all-repeated=prepend | grep "^$" -a3 should work uniq -f1 gives me different uniq -f1 --all-repeated=prepend. understand correctly prepend should add emtpy line before unique chunk?

or there better approach?

thanks

here's 1 idea using awk:

awk -v maxlines=<n> ' ++count[$2] <= maxlines { print } ' 

that not require sorting file (but still sort first if there other reasons want to...).