原因12.04中将/dev/shm目录改成了/run/shm，虽然已经有符号链接但是仍然报错。
解决：
1、编辑oracle-shm
sundoctor@sundoctor-ThinkPad-W510:~$ sudo gedit /etc/init.d/oracle-shm
#! /bin/sh
# /etc/init.d/oracle-shm
#
#
case $1 in
start)
echo "Starting script /etc/init.d/oracle-shm"
# Run only once at system startup
if [ -e /dev/shm/.oracle-shm ]; then
echo "/dev/shm is already mounted, nothing to do"
else
rm -f /dev/shm
mkdir /dev/shm
#mount -B /run/shm /dev/shm
mount --move /run/shm /dev/shm
mount -B /dev/shm /run/shm
touch /dev/shm/.oracle-shm
fi
;;
stop)
echo "Stopping script /etc/init.d/oracle-shm"
echo "Nothing to do"
;;
*)
echo "Usage:/etc/init.d/oracle-shm {start|stop}"
exit 1
;;
esac
#
### BEGIN INIT INFO
# Provides: oracle-shm
# Required-Start: $remote_fs $syslog
# Required-Stop: $remote_fs $syslog
# Default-Start: 2 3 4 5
# Default-Stop: 0 1 6
# Short-Description:Bind /run/shm to /dev/shm at system startup.
# Description: Fix to allow Oracle 11g use AMM.
### END INIT INFO
2、安装oracle-shm
sundoctor@sundoctor-ThinkPad-W510:~$sudo chmod 755 /etc/init.d/oracle-shm
sundoctor@sundoctor-ThinkPad-W510:~$sudo update-rc.d oracle-shm defaults 01 99
3、重启系统
sundoctor@sundoctor-ThinkPad-W510:~$sudo shutdown -r now
4、验证修改成功
sundoctor@sundoctor-ThinkPad-W510:~$sudo cat /etc/mtab |grep shm
none /dev/shm tmpfs rw,nosuid,nodev 0 0
/dev/shm /run/shm none rw,bind 0 0
５、启动数据库
sundoctor@sundoctor-ThinkPad-W510:~$su – oracle
sundoctor@sundoctor-ThinkPad-W510:~$dbstart
成功！！！