Processs each character in a file

bash.sh

#!bin/bash

while IFS= read -r line
do
    for i in $(seq 0 $(expr length "$line"))
    do
        # print each character
        c="${line:$i:1}"
        echo -n c
    done
done < input.txt

python.py

with open('input.txt') as f:
    for line in f:
        for c in line:
            # print each character
            print(c)
        print("\n")