You can pre-sort as greyfade mentions, or do it within awk itself: awk '!/#/ {a[$2]++}END{for (i in a) print a[i],i | "sort -nk1"}' data.txt 1 0 1 202 1 2

You can pre-sort as greyfade mentions, or do it within awk itself: awk '!/#/ {a[$2]++}END{for (i in a) print a[i],i | "sort -nk1"}' data.txt 1 0 1 202 1 289 1 291 1 298 1 311 4 104