1. install globally npm install -g ceasar-cli.
2. Then you run my_caesar_cli with the following flags:

3. • required:

     • -a or --action - an action to perform, either decode or encode. Throws an error otherwise.
     • -s or --shift - a shift by how many numbers to shift the alphabet, positive integers from 1. Throws an error if the flag is omitted.

   • optional:

     • -i or --input - a text-file to read an input from. It's better be an existing text-file or an error is thrown. If the flag is omitted, the input is read from the console.
     • -o or --output - a text-file to write an output to. It's better be an existing text-file or an error is thrown. If the flag is omitted, the output is written to the console.

You can also run my_caesar_cli --help to see examples how to yse this CLI:

- my_caesar_cli -a encode -s 7 -i "./input.txt" -o "./output.txt"
- my_caesar_cli --action encode --shift 7 --input plain.txt --output encoded.txt
- my_caesar_cli --action decode --shift 7 --input encoded.txt --output plain.txt
- my_caesar_cli --action encode --shift 7 --output plain.txt
- my_caesar_cli --action decode --shift 7 --input decoded.txt
- my_caesar_cli --action encode --shift 7
- my_caesar_cli --action decode --shift 7