function csvdiff() {
  if [ "$1" == "-s" ] ; then
    local s_args="<(sort $2) <(sort $3)"
    shift
  fi
  
  awk '
    NR==FNR { file1[FNR]=$0; next }
    FNR==(h?h:1) {
      if (!D) {
        char["\t"]=gsub(/\t/, "\t")
        char[","]=gsub(/,/, ",")
        char["|"]=gsub(/\|/, "|")
        char[";"]=gsub(/;/, ";")
        for (c in char) {
          if (char[c] >= max) {
            max=char[c]
            delim=c
          }
        }
        max=0
      }
      else delim=D

      if (h != 0 || h == "") {
        split($0, a, delim)
    
        for (i=1;i<=length(a);i++) {
          header[i]=a[i]
        }
        next
      }
    }
    FNR>(h?h:0) && file1[FNR] {
      split(file1[FNR], a, delim)
      split($0, b, delim)
      for (i=1;i<=length(a);i++) {
        if (a[i] != b[i])  {
          diff[i]++
          if (col == i) printf "%-1s%s%s\n", a[i], OFS, b[i]
        }
      }
    }
    END {
      if (FNR != length(file1)) {
        print "error: number of lines do not match: " length(file1), FNR
        exit
      }
      if (!col) {
        if (length(diff)) {
          print "column differences:"
          for (i in diff) {
            print i " " header[i] ": " diff[i]
          }
        }
        else {
          print "no differences found"
        }
      }
    }' OFS="\t" ${s_args-$@}
}