UNIX for Dummies Questions & Answers

BEGIN {
  if (col=="") col=1
}

function uniq(list,  i,n,a,ret, str) {
  split("", ret)
  split(list, a, FS)
  for(i=1; i in a; i++)
     if (!(a[i] in ret)) {
       ret[a[i]]
       str=(str=="") ? a[i] : str FS a[i]
     }
  return(str)
}
NR==FNR {
  one[$col]= ($col in one) ? one[$col] FS $0 : $0
  next
}
{
  two[$col]= ($col in two) ? two[$col] FS $0 : $0
}
END {
  for(iter in one)
    if(iter in two)
      print uniq(one[iter] FS two[iter])
}