Making Multiple MySQL Instances on One Server

#!/bin/bash
#
# mysqld        This shell script takes care of starting and stopping
#               the MySQL subsystem (mysqld).
#
# chkconfig: - 64 36
# description:  MySQL database server.
# processname: mysqld
# config: /etc/master-a.cnf
# pidfile: /dbases/master-a/mysqld.pid

# Source function library.
. /etc/rc.d/init.d/functions

# Source networking configuration.
. /etc/sysconfig/network

prog="MySQL"

# extract value of a MySQL option from config files
# Usage: get_mysql_option SECTION VARNAME DEFAULT
# result is returned in $result
# We use my_print_defaults which prints all options from multiple files,
# with the more specific ones later; hence take the last match.
get_mysql_option(){
        result=/usr/bin/my_print_defaults "$1" | sed -n "s/^--$2=//p" | tail -n 1
        if [ -z "$result" ]; then
            # not found, use default
            result="$3"
        fi
}

get_mysql_option mysqld datadir "/dbases/master-a"
datadir="/dbases/master-a"
get_mysql_option mysqld socket "/dbases/master-a/mysql.sock"
socketfile="/dbases/master-a/mysql.sock"
get_mysql_option mysqld_safe log-error "/dbases/master-a/mysqld.log"
errlogfile="/dbases/master-a/mysqld.log"
get_mysql_option mysqld_safe pid-file "/dbases/master-a/mysqld.pid"
mypidfile="/dbases/master-a/mysqld.pid"

defaultfile="/etc/master-a.cnf"

start(){
        touch "$errlogfile"
        chown mysql:mysql "$errlogfile"
        chmod 0640 "$errlogfile"
        [ -x /sbin/restorecon ] && /sbin/restorecon "$errlogfile"
        if [ ! -d "$datadir/mysql" ] ; then
            action $"Initializing MySQL database: " /usr/bin/mysql_install_db --datadir="$datadir" --user=mysql
            ret=$?
            chown -R mysql:mysql "$datadir"
            if [ $ret -ne 0 ] ; then
                return $ret
            fi
        fi
        chown mysql:mysql "$datadir"
        chmod 0755 "$datadir"
        # Pass all the options determined above, to ensure consistent behavior.
        # In many cases mysqld_safe would arrive at the same conclusions anyway
        # but we need to be sure.
        /usr/bin/mysqld_safe  --defaults-file="$defaultfile" --datadir="$datadir" --socket="$socketfile" \
                --log-error="$errlogfile" --pid-file="$mypidfile" \
                --user=mysql >/dev/null 2>&1 &
        ret=$?
        # Spin for a maximum of N seconds waiting for the server to come up.
        # Rather than assuming we know a valid username, accept an "access
        # denied" response as meaning the server is functioning.        
        if [ $ret -eq 0 ]; then
            STARTTIMEOUT=30
            while [ $STARTTIMEOUT -gt 0 ]; do
                RESPONSE=/usr/bin/mysqladmin --socket="$socketfile" --user=UNKNOWN_MYSQL_USER ping 2>&1 && break
                echo "$RESPONSE" | grep -q "Access denied for user" && break
                sleep 1
                let STARTTIMEOUT=${STARTTIMEOUT}-1
            done
            if [ $STARTTIMEOUT -eq 0 ]; then
                    echo "Timeout error occurred trying to start MySQL Daemon."
                    action $"Starting $prog: " /bin/false
                    ret=1
            else
                    action $"Starting $prog: " /bin/true
            fi
        else
            action $"Starting $prog: " /bin/false
        fi
        [ $ret -eq 0 ] && touch /dbases/master-a/mysqld
        return $ret
}

stop(){ 
        MYSQLPID=cat "$mypidfile"  2>/dev/null 
        if [ -n "$MYSQLPID" ]; then
            /bin/kill "$MYSQLPID" >/dev/null 2>&1
            ret=$?
            if [ $ret -eq 0 ]; then
                STOPTIMEOUT=60
                while [ $STOPTIMEOUT -gt 0 ]; do
                    /bin/kill -0 "$MYSQLPID" >/dev/null 2>&1 || break
                    sleep 1
                    let STOPTIMEOUT=${STOPTIMEOUT}-1
                done
                if [ $STOPTIMEOUT -eq 0 ]; then
                    echo "Timeout error occurred trying to stop MySQL Daemon."
                    ret=1
                    action $"Stopping $prog: " /bin/false
                else
                    rm -f /dbases/master-a/mysqld
                    rm -f "$socketfile"
                    action $"Stopping $prog: " /bin/true
                fi
            else
                action $"Stopping $prog: " /bin/false
            fi
        else
            ret=1
            action $"Stopping $prog: " /bin/false
        fi
        return $ret
}

restart(){
    stop
    start
}

condrestart(){
    [ -e /dbases/master-a/mysqld ] && restart || :
}

# See how we were called.
case "$1" in
  start)
    start
    ;;
  stop)
    stop
    ;;
  status)
    status mysqld
    ;;
  restart)
    restart
    ;;
  condrestart)
    condrestart
    ;;
  *)
    echo $"Usage: $0 {start|stop|status|condrestart|restart}"
    exit 1
esac

exit $?