1. 以oracle用户登录linux操作系统
   执行命令：su - oracle
   注意：“-” 两边都有空格
   [root@Slave ~]# su - oracle
   Last login: Sun Sep 30 09:29:08 CST 2018 on pts/1
   -bash-4.2$

2. 以dba身份登录oracle数据库
   执行命令：sqlplus / as sysdba

    -bash-4.2$ sqlplus / as sysdba
    
    SQL*Plus: Release 11.2.0.1.0 Production on Sun Sep 30 09:54:23 2018
    
    Copyright (c) 1982, 2009, Oracle.  All rights reserved.
    
    
    Connected to:
    Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
    With the Partitioning, OLAP, Data Mining and Real Application Testing options
    
    SQL>

3. 执行以下命令修改用户密码

SQL中执行：alter user sys identified by change_on_install;

SQL> alter user sys identified by change_on_install;

User altered.

SQL> exit
Disconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
-bash-4.2$