Tips for modifying the Oracle user password

Sometimes we may not know the password of a user, but we need to perform some operations with this user, and we cannot modify the password of this user. At this time, we can use some tips, to complete the operation.
The procedure is as follows:
SQL * Plus:
Release 9.2.0.5.0-production on Sunday November 21 13:32:34 2004
Copyright (c)
1982,200 2, Oracle Corporation. All rights reserved.
SQL> Connect
Sys/Oracle AS sysdba
Connected.
SQL> Select username, password from
Dba_users;
Username Password
------------------------------
------------------------------
Sys 8a8f025737a9097a
System
2d594e86f93b17a1
Dbsnmp e066d214d5421ccc
Toad
A1ba01cf0dd82695
Outln 4a3ba55e08595c81
Wmsys
7c9ba362f8314299
You have selected 6 rows.
SQL> connect
System/Oracle
Connected.
SQL> connect sys/Oracle
Sysdba
Connected.
Change User System Password to Manager
SQL> Alter User System
Identified by manager;
The user has changed.
SQL> select username, password from
Dba_users;
Username Password
------------------------------
------------------------------
Sys 8a8f025737a9097a
System
D4df7931ab130e37
Dbsnmp e066d214d5421ccc
Toad
A1ba01cf0dd82695
Outln 4a3ba55e08595c81
Wmsys
7c9ba362f8314299
You have selected 6 rows.
SQL> connect
System/Manager
Connected.
Then, you can perform any operations you want.
SQL> connect sys/Oracle
As sysdba
Connected.
Change the user's system password to a previous value.
SQL> alter User System
Identified by values '2d594e86f93b17a1 ';
The user has changed.
SQL> connect
System/Oracle
Connected.
SQL> connect sys/Oracle
Sysdba
Connected.
SQL> connect system/Manager
Error:
ORA-01017:
Invalid username/password; logon denied
Warning: you are no longer connected to Oracle.