UNIX for Dummies Questions & Answers

        s[NR] = sprintf ("-%c", ++c[$1]+96)  # assign lower case letter in increasing sequence

(++c[$1]>26 ? 34 : c[$1]+96)

# Usage: awk -f this_file  input_file
# variable index:
#       c[line contents]        Count of occurrences of input line with the
#                               same contents indexed by input line $0.
#
#       i                       Output loop index.
#
#       o[line#]                Main contents of output line indexed by NR or i.
#
#       s[line#]                Suffix for output line indexed by NR.  (Printed
#                               only when c[i] > 1.)
#
#       suffices[count*2+1]     Array of 2 character substrings to be used as
#                               the suffix for output lines that correspond to
#                               input lines that appear multiple times.  The
#                               first two characters are a special case used
#                               when an input line appears more than 26 times.
BEGIN { suffices="-*-a-b-c-d-e-f-g-h-i-j-k-l-m-n-o-p-q-r-s-t-u-v-w-x-y-z"}
{       s[NR] = substr(suffices, ++c[o[NR] = $1] > 26 ? 1 : c[$1] * 2 + 1, 2)}
END {   for(i = 1; i <= NR; i++)
                printf("%s%s\n", o[i], c[o[i]] > 1 ? s[i] : "")
}