Centos7操作系统下安装oracle18c
Oracle官方已经放出18c企业版的rpm安装包，但仅限于单机版安装，相对于之前的版本，省去了前期规划配置的繁琐步骤
1、 下载oracle RPM安装包

2、 使用yum安装
使用oracle软件源安装，保证RPM安装默认的目录是/opt,安装前确保/opt拥有足够的空间
[root@iZ8vb7sjth4p01s4r1b1emZ backup]# yum -y localinstall oracle-database-preinstall-18c-1.0-1.el7.x86_64.rpm
安装oracle18c的RPM软件包
[root@iZ8vb7sjth4p01s4r1b1emZ backup]# yum -y localinstall oracle-database-ee-18c-1.0-1.x86_64.rpm
3、 配置oracle 18c数据库
安装完成后会生成两个文件：
1、 一个是管理oracle服务的脚本(/etc/init.d/oracledb_ORCLCDB-18c)
修改oracledb_ORCLCDB-18c配置文件

Setting the required environment variables

export ORACLE_HOME=/opt/oracle/product/18c/dbhome_1

export ORACLE_VERSION=18c
export ORACLE_SID=CYCDB
export TEMPLATE_NAME=General_Purpose.
export CHARSET=ZHS16GBK
export PDB_NAME=ERP
export LISTENER_NAME=LISTENER
export NUMBER_OF_PDBS=1
export CREATE_AS_CDB=true

General exports and vars

export PATH=$ORACLE_HOME/bin:$PATH
LSNR=$ORACLE_HOME/bin/lsnrctl SQLPLUS=$ORACLE_HOME/bin/sqlplus
DBCA=ORACLE_HOME/bin/dbca ORACLE_OWNER=oracle RETVAL=0 CONFIG_NAME="oracledb_ORACLE_SID-$ORACLE_VERSION.conf" CONFIGURATION="/etc/sysconfig/$CONFIG_NAME"
2、 另一个是定义数据文件存放路径的文件(/etc/sysconfig/oracledb_ORCLCDB-18c.conf)
修改配置文件oracledb_ORCLCDB-18c.conf
[root@iZ8vb7sjth4p01s4r1b1emZ sysconfig]# cat oracledb_ORCLCDB-18c.conf
#This is a configuration file to setup the Oracle Database.
#It is used when running ‘/etc/init.d/oracledb_ORCLCDB configure’.
#Please use this file to modify the default listener port and the
#Oracle data location.

LISTENER_PORT: Database listener

LISTENER_PORT=1521

ORACLE_DATA_LOCATION: Database oradata location

ORACLE_DATA_LOCATION=/oradata

EM_EXPRESS_PORT: Oracle EM Express listener

EM_EXPRESS_PORT=5500
[root@iZ8vb7sjth4p01s4r1b1emZ sysconfig]#
3、 修改完成后，执行/etc/init.d/oracledb_ORCLCDB-18c configure命令创建数据库实例以及监听
[root@iZ8vb7sjth4p01s4r1b1emZ /]# /etc/init.d/oracledb_CYCDB-18c configure
Configuring Oracle Database CYCDB.
Prepare for db operation
8% complete
Copying database files
31% complete
Creating and starting Oracle instance
32% complete
36% complete
40% complete
43% complete
46% complete
Completing Database Creation
51% complete
54% complete
Creating Pluggable Databases
58% complete
77% complete
Executing Post Configuration Actions
100% complete
Database creation complete. For details check the logfiles at:
/opt/oracle/cfgtoollogs/dbca/CYCDB.
Database Information:
Global Database Name:CYCDB
System Identifier(SID):CYCDB
Look at the log file “/opt/oracle/cfgtoollogs/dbca/CYCDB/CYCDB.log” for further details.

Database configuration completed successfully. The passwords were auto generated, you must change them by connecting to the database using ‘sqlplus / as sysdba’ as the oracle user.
[root@iZ8vb7sjth4p01s4r1b1emZ /]#
其实，这个configure就是调用dbca的静默模式创建数据库实例。创建完成后，根据上面的提示修改系统用户的密码即可。
配置
添加环境变量
export ORACLE_HOME=/opt/oracle/product/18c/dbhome_1
PATH=$PATH:$HOME/.local/bin:$HOME/bin:$ORACLE_HOME/bin
修改数据库的密码
SQL> alter user sys identified by “123123”;
SQL> alter user system identified by “123123”;