This script creates a database 'db' and a user as 'username' with given password 'pass'. It also grant 'username' ALL access to 'db'. Works on any linux.

create-db-user.sh

#!/bin/bash
# A shell script to add mysql database, username and password. 
# -------------------------------------------------------------------------
_db="$1"
_user="$2"
_pass="$3"
 
## Mysql root settings ##
_madminuser='root'
_madminpwd='mysql-root-password'
 

# make sure we get 3 args, else die
[[ $# -le 2 ]] && { echo "Usage: $0 'DB_Name' 'DB_USER' 'DB_PASSORD' "; exit 1; }

echo 'FLUSH PRIVILEGES;' > /tmp/sql
 
# create DB
query=" CREATE DATABASE ${_db} ;";
echo $query >> /tmp/sql

# grant permission
query=" GRANT ALL ON ${_db}.* TO ${_user} IDENTIFIED BY '${_pass}';";
echo $query >> /tmp/sql

 #check db and permission
query="SELECT Host, Db, User FROM mysql.db WHERE User='${_user}' and Db='${_db}';";
echo $query >> /tmp/sql

echo "Running: [sudo mysql -u${_madminuser} --password=\"${_madminpwd}\" < /tmp/sql]"
sudo mysql -u${_madminuser} --password="${_madminpwd}" < /tmp/sql