RosettaCodeData/Task/Letter-frequency/Ksh/letter-frequency.ksh

#!/bin/ksh

# Count the occurrences of each character

 ######
# main #
 ######

typeset -iA freqCnt
while read; do
  for ((i=0; i<${#REPLY}; i++)); do
    (( freqCnt[${REPLY:i:1}]++ ))
  done
done < $0   ## Count chars of this code file

for ch in "${!freqCnt[@]}"; do
  [[ ${ch} == ?(\S) ]] && print -- "${ch}  ${freqCnt[${ch}]}"
done