Shell Programming and Scripting

awk '
{s[$0]++}
END {
  for(i in s) {
    if(s[i]>1) {
      print i
    }
  }
}' ${TMP_DUPE_RECS}>>${TMP_BAD_DATA_DUPE_RECS}

awk '
{s[$0]++}
END {
  for(i in s) {
  for(j=1;j<s[i];j++){
      print i;
  }
  }
}' ${TMP_DUPE_RECS}>${TMP_BAD_DATA_DUPE_RECS}

awk '
{s[$0]++}              # this populate an array, the number of elements is the distinct value in the file (A B C) 
END {                  # and the value is the count of each element: eg. if i=A --> s[i]=3
  for(i in s) {        # for each distinct value i in s
  for(j=1;j<s[i];j++){ # s[i] is the count of element i: in this way
      print i;         # print s[i]-1 times the element i
  }
  }
}' ${TMP_DUPE_RECS}>${TMP_BAD_DATA_DUPE_RECS}

awk 'c[$0]++{print}' ${TMP_DUPE_RECS}>${TMP_BAD_DATA_DUPE_RECS}

awk 'c[$0]++==0{print}' ${TMP_DUPE_RECS}>${TMP_BAD_DATA_DUPE_RECS}

A
  A
  B
  C

awk 'c[$1]++{print}' ${TMP_DUPE_RECS}>${TMP_BAD_DATA_DUPE_RECS}

  A
  A
  B

$ uniq -c temp.x | grep -v " 1 "
      3 A
      2 B