get_short_name.sh

function get_short_name() {
    short_name=''

    for i in ${!fullname[@]}; do
        if ((i < ${#fullname[@]} - 1)); then
            short_name+="${fullname[i]::1}. "
        else
            short_name+=${fullname[i]}
        fi
    done
    
    echo $short_name
}

read -a fullname

echo $(get_short_name $short_name)