Try using a here document like this:
mysql --host=localhost --user=user --password=password << END
CREATE USER 'testuser'@'localhost' IDENTIFIED BY 'jakdJxct8W';
CREATE DATABASE IF NOT EXISTS 'testuser_dev' DEFAULT CHARACTER SET utf8 COLLATE utf8_bin;
GRANT ALL PRIVILEGES ON 'testuser_dev' . * TO 'testuser'@'localhost';
CREATE DATABASE IF NOT EXISTS 'testuser_qa' DEFAULT CHARACTER SET utf8 COLLATE utf8_bin;
GRANT ALL PRIVILEGES ON 'testuser_qa' . * TO 'testuser'@'localhost';
END
Alternatively place all you commands in text file and run it:
mysql --host=localhost --user=user --password=password < commands.sql