2018年9月，Oracle支持通过yum安装Oracle数据库instant client。见这里。
目前可以安装的包如下，也可以看这里：
$ yum search instantclient
Loaded plugins: langpacks, ulninfo
===================================================== N/S matched: instantclient ======================================================
oracle-instantclient12.2-basic.x86_64 : Oracle Instant Client Basic package
oracle-instantclient12.2-basiclite.x86_64 : Oracle Instant Client Light package
oracle-instantclient12.2-devel.x86_64 : Development headers for Instant Client.
oracle-instantclient12.2-jdbc.x86_64 : Supplemental JDBC features for the Oracle Instant Client
oracle-instantclient12.2-odbc.x86_64 : ODBC Instant Client.
oracle-instantclient12.2-precomp.x86_64 : Precompiler support for Instant Client.
oracle-instantclient12.2-sqlplus.x86_64 : SQL*Plus for Instant Client.
oracle-instantclient12.2-tools.x86_64 : Tools for Oracle Instant Client
oracle-instantclient18.3-basic.x86_64 : Oracle Instant Client Basic package
oracle-instantclient18.3-basiclite.x86_64 : Oracle Instant Client Light package
oracle-instantclient18.3-devel.x86_64 : Development headers for Instant Client.
oracle-instantclient18.3-jdbc.x86_64 : Supplemental JDBC features for the Oracle Instant Client
oracle-instantclient18.3-odbc.x86_64 : Oracle Instant Client ODBC
oracle-instantclient18.3-precomp.x86_64 : Precompiler support for Instant Client.
oracle-instantclient18.3-sqlplus.x86_64 : SQL*Plus for Instant Client.
oracle-instantclient18.3-tools.x86_64 : Tools for Oracle Instant Client
要理解这些包的含义和关系，可以参考这里。简单来说，basic是必装的，其它如sqlplus是可选的。
在Oracle Linux上通过yum安装最方便，无需配置repository之类。其它平台的安装可参见这里。
以下为示例：
$ sudo yum install -y oracle-instantclient18.3-basic oracle-instantclient18.3-sqlplus
sqlplus的目录如下：
$ sudo find / -name sqlplus
/usr/lib/oracle/18.3/client64/bin/sqlplus
需要设置以下的环境变量：
$ export CLIENT_HOME=/usr/lib/oracle/18.3/client64
$ export LD_LIBRARY_PATH=$CLIENT_HOME/lib
$ export PATH=$PATH:$CLIENT_HOME/bin
然后就可以用sqlplus连接数据库了。
