1、进入oracle官网 https://www.oracle.com/database/technologies/instant-client/linux-x86-64-downloads.html

下载：

oracle-instantclient-basic-21.3.0.0.0-1.el8.x86_64.rpm
oracle-instantclient-sqlplus-21.3.0.0.0-1.el8.x86_64.rpm
oracle-instantclient-devel-21.3.0.0.0-1.el8.x86_64.rpm

依次安装：

rpm -ivh oracle-instantclient-basic-21.3.0.0.0-1.el8.x86_64.rpm
rpm -ivh oracle-instantclient-sqlplus-21.3.0.0.0-1.el8.x86_64.rpm
rpm -ivh oracle-instantclient-devel-21.3.0.0.0-1.el8.x86_64.rpm

安装的文件默认放在两个位置： 头文件：/usr/include/oracle/21/client64 下，如果在使用时报错找不到头文件，记得看路径是否是这个。 包文件：/usr/lib/oracle/21/client64下，包含{bin、lib}两个文件夹；

2、创建监听文件，并添加内容

cd /usr/lib/oracle/21/client64/lib/network/admin

vi tnsnames.ora

ORCL =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = 192.169.1.109)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = orcl)
    )
  )

Note:host是远程数据库的ip地址，service_name为远程数据库的sid

配置环境变量 vi /etc/profile，添加

#配置ORACLE环境变量 vi /etc/profile
export ORACLE_BASE=/usr/lib/oracle/21
export ORACLE_VERSION=21
export ORACLE_HOME=/usr/lib/oracle/21/client64
export LD_LIBRARY_PATH=$ORACLE_HOME/lib:$LD_LIBRARY_PATH
export SQLPATH=$ORACLE_HOME/lib/network/admin
export TNS_ADMIN=$ORACLE_HOME/lib/network/admin
export NLS_LANG=AMERICAN_AMERICA.AL32UTF8
#export NLS_LANG="Simplified Chinese_china".ZHS16GBK
export PATH=$PATH:$HOME/bin:$ORACLE_HOME/bin

配置保存后 source /etc/profile 即可使配置即时生效 之后连接数据库测试 sqlplus username/password@ORCL