Wrapper to simplify base64 usage

b64.sh

#!/usr/bin/env bash

script_name=$(egrep -o "[^\/]*$" <<< "$0")

function help {
    printf '%s\n' "Usage:"
    printf '%s\n' "  $script_name e input output → encode to output"
    printf '%s\n' "  $script_name e input → encode to stdout"
    printf '%s\n' "  $script_name d input output → decode to output"
    printf '%s\n' "  $script_name d input → decode to stdout"
    exit "$1"
}

function encode {
    printf '%s' "$(sed ':a;N;$!ba;s|\n||g' <(base64 "$1"))"
}

function decode {
    base64 -di < "$1"
}

if [[ -z "$1" ]]; then
    help 0
elif [[ -n "$3" ]]; then
    if [[ -f "$2" ]]; then
        case $1 in
            e)
                encode "$2" > "$3"
                ;;
            d)
                decode "$2" > "$3"
                ;;
            *)
                help 1
                ;;
        esac
    else
        printf '%s\n' 'Error: invalid input file' >&2
    fi
elif [[ -n "$2" ]]; then
    if [[ -f "$2" ]]; then
        case $1 in
            e)
                encode "$2"
                ;;
            d)
                decode "$2"
                ;;
            *)
                help 1
                ;;
        esac
    else
        printf '%s\n' 'Error: invalid input file' >&2
    fi
else
    help 1
fi