I just need Memcached to start automatically when reboot so that I don't have to wait to log into the server to do that every time I restart my server. The problem here is that I didn't install Memcached using YUM. I compiled Memcached it myself. So, there is no startup script for me to do it. Also, from what I have read, init.d startup script comes with YUM only support one instance of Memcached. In my case, I need to run multiple instances of Memcached. So, I searched for the script and below script is work for me

1. Create Script in /etc/init.d/memcached

#!/bin/bash
#
# Init file for memcached
#
# Written by Dag Wieërs 
#
# chkconfig: - 80 12
# description: Distributed memory caching daemon
#
# processname: memcached
# config: /etc/sysconfig/memcached
# config: /etc/memcached.conf

source /etc/rc.d/init.d/functions

### Read configuration
#[ -r "$SYSCONFIG" ] && source "$SYSCONFIG"

FILES=(/etc/sysconfig/memcached_*);
# check for alternative config schema
if [ -r "${FILES[0]}" ]; then
	CONFIGS=();
  	for FILE in "${FILES[@]}";
  	do
		# remove prefix
		#echo "${FILE} ==> file"
		NAME=${FILE#/etc/sysconfig/};
		# check optional second param
		if [ $# -ne 2 ];
		then
		  # add to config array
		  CONFIGS+=($NAME);
		elif [ "$2" == "$NAME" ];
		then
		  # use only one memcached
		  CONFIGS=($NAME);
		  break;
		fi;
  	done;
  if [ ${#CONFIGS[@]} == 0 ];
  then
    echo "Config not exist for: $2" >&2;
    exit 1;
  fi;
else
  CONFIGS=(memcached);
fi;

CONFIG_NUM=${#CONFIGS[@]};
for ((i=0; i < $CONFIG_NUM; i++)); do
  NAME=${CONFIGS[${i}]};
  PIDFILE="/var/run/memcached/${NAME}.pid";
  #echo "LOOP \"$CONFIG_NUM\""
  #echo "config ==> ${NAME}"
  #echo "$PIDFILE ==> PID"

##

RETVAL=0
#prog="memcached"
prog="${NAME}"
source "/etc/sysconfig/${NAME}"
desc="Distributed memory caching"

start() {
	echo -n $"Starting $desc (${NAME}): "
	daemon --pidfile $PIDFILE /usr/local/bin/memcached -P $PIDFILE -d -p $PORT -u $USER -c $MAXCONN -m $CACHESIZE $OPTIONS
	#echo " $prog -d -p $PORT -U $PORT -u $USER -c $MAXCONN -m $CACHESIZE $OPTIONS"
	RETVAL=$?
	echo
	[ $RETVAL -eq 0 ] && touch /var/lock/subsys/$prog
	return $RETVAL
}

stop() {
	echo -n $"Shutting down $desc ($prog): "
	echo "$PIDFILE"
	killproc -p $PIDFILE memcached 
	RETVAL=$?
	echo
	[ $RETVAL -eq 0 ] && rm -f /var/lock/subsys/$prog
	return $RETVAL
}

restart() {
	stop
	start
}

reload() {
	echo -n $"Reloading $desc ($prog): "
	killproc $prog -HUP
	RETVAL=$?
	echo
	return $RETVAL
}

case "$1" in
  start)
	start
	;;
  stop)
	stop
	;;
  restart)
	restart
	;;
  condrestart)
	[ -e /var/lock/subsys/$prog ] && restart
	RETVAL=$?
	;;
  reload)
	reload
	;;
  status)
	status -p $PIDFILE $prog
	RETVAL=$?
	;;
   *)
	echo $"Usage: $0 {start|stop|restart|condrestart|status}"
	RETVAL=1
esac

##$RETVAL

done;

Note that when install Memcached using YUM, the path of Memcached is /usr/bin/memcached but if you compiled it by yourself, the path will be /usr/local/bin/memcached. The latter is what I put in the script.

2. CHMOD memcached startup script to 755

chmod 755 /etc/init.d/memcached

3. Create Memcached configuration files. You can created as many as you want in /etc/sysconfig/. The format of the file has to be memcached_PORT like memcached_11211, memcache_11212 .... Each file will contain configuration below :

memcached_11211

PORT="11211"
USER="nobody"
MAXCONN="2048"
CACHESIZE="64"
OPTIONS=""

memcached_11212

PORT="11212"
USER="nobody"
MAXCONN="2048"
CACHESIZE="256"
OPTIONS="-L -l 127.0.0.1"

You can add addition option in OPTIONS. Something like -L

4. Create a folder to keep all Memcached PID files :

mkdir /var/run/memcached
chmod 755 /var/run/memcached
chown nobody:nobody /var/run/memcached

5. Usage :

Startup command

  /etc/init.d/memcached start
  /etc/init.d/memcached start memcached_11211
  service memcached start
  service memcached start memcached_11211

Status command

  /etc/init.d/memcached status
  /etc/init.d/memcached status memcached_11211
  service memcached status
  service memcached status memcached_11211

Stop command

  /etc/init.d/memcached stop
  /etc/init.d/memcached stop memcached_11211
  service memcached stop
  service memcached stop memcached_11211

6. Now you may need Memcached to startup when your computer reboot. Here is what I did :

chkconfig --level 345 memcached on

Then, check if memcached is already added to chkconfig

chkconfig --list | grep "memcached"

Below is what I got :

# chkconfig --list | grep "memcached"
memcached      	0:off	1:off	2:off	3:on	4:on	5:on	6:off

Server Information - Software
- CentOS 5.6 - 64 bits
- Memcached 1.4.6

Source :
- http://addmoremem.blogspot.com/2010/09/running-multiple-instances-of-memcached.html