tocase - Change the lower and upper case characters.

tocase

#!/usr/bin/env bash

if [ "${#}" -eq 0 ] ; then
    cat << EOF
usage: tocase option...

options:
    upper       all uppercase
    upper1      upper first character

    lower       all lowercase
    lower1      lower first character

    toggle      swap uppercase and lowercase
    toggle1     swap upper and lower of first character

    title       upper first character and lower rest of each word

examples:
    echo "Hello World, this is an EXAMPLE." | tocase toggle upper1
EOF
exit 0
fi

while IFS= read -r stdin ; do
    for argument in "${@}" ; do
        case "${argument}" in
        upper) stdin="${stdin^^}" ;;
        upper1) stdin="${stdin^}" ;;
        lower) stdin="${stdin,,}" ;;
        lower1) stdin="${stdin,}" ;;
        toggle) stdin="${stdin~~}" ;;
        toggle1) stdin="${stdin~}" ;;
        title)
            # Note: Many other solutions other than this sed command do not 
            # work on each word.
            stdin="$(sed -r 's/\<./\U&/g' <<<"${stdin}")"
            ;;
        esac
    done

    printf "%s\n" "${stdin}"
done