Create USER and DB following format ${USER}_db

create-db-and-user.sh

#!/bin/bash

if [ -z "$1" ]
  then
    echo "Database name is not specified."
    exit
fi

USER=$1
PASS=`pwgen -s 16 1`
DB_NAME=${USER}_db

# if mysql >= 8.0
COLLATION=utf8mb4_0900_ai_ci
# else
# COLLATION=utf8mb4_unicode_ci

mysql -uroot <<MYSQL_SCRIPT
CREATE DATABASE $DB_NAME DEFAULT CHARACTER SET utf8mb4 DEFAULT COLLATE $COLLATION;
CREATE USER '$USER'@'localhost' IDENTIFIED BY '$PASS';
GRANT ALL PRIVILEGES ON $DB_NAME.* TO '$USER'@'localhost';
FLUSH PRIVILEGES;
MYSQL_SCRIPT

echo "Done."
echo "Database:   $DB_NAME"
echo "Username:   $USER"
echo "Password:   $PASS"