Fill whole terminal by alphabet.

draw.sh

#!/bin/bash

lins=`tput lines`
cols=`tput cols`

printf '\033c'

for x in {a..z}; do
  for ((l=0; l<=lins; l++)); do
    for ((c=0; c<=cols-1; c++)); do
      echo -ne "$x"
    done

    if [ "$l" -ne "$lins" ]; then
      echo -ne "\n"
    fi
  done

  tput cup 0 0
done

echo -ne "\n"
printf '\033c'