ref: 96c2be96e4beaac08d89af4dea8069d9ca1c4b09 dir: /test/t.array1/
{for(i=1; i<=NF; i++) { if (x[$i] == "") y[++n] = $i x[$i]++ } } END { for (i=0; i<n; i++) print (y[i], x[y[i]]) }