256_colors.sh

#!/bin/bash

echo -en "\n   +  "

for i in {0..35}; do
  printf "%2b " $i
done

printf "\n\n %3b  " 0

for i in {0..15}; do
  echo -en "\033[48;5;${i}m  \033[0m "
done

for i in {0..6}; do
  let "i = i*36 +16"
  printf "\n\n %3b  " $i
  for j in {0..35}; do
    let "val = i+j"
    echo -en "\033[48;5;${val}m  \033[0m "
  done
done

echo -e "\n"