$ export MYSQL_PWD=$(>&2 read -s -p "Input password (will not echo): "; echo "$REPLY")
$ mysqldump -u root mysql | head
-- MySQL dump 10.13 Distrib 5.6.23, for Linux (x86_64)
--
-- Host: localhost Database: mysql
-- ------------------------------------------------------
-- Server version 5.6.23
/*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */;
/*!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */;
/*!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */;
/*!40101 SET NAMES utf8 */;
[mysqldump]
#use this if your password has special characters (!@#$%^&..etc) in it
password="YourPasswordWithSpecialCharactersInIt"
#use this if it has no special characters
password=myPassword