原因：

二、将挂载设备卸下时出现的错误

# umount /usr/local/

umount: /usr/local: device is busy

解决方法：fuser –km /usr/local/

fuser的用法:

       -k     Kill processes accessing the file. Unless changed with -signal, SIGKILL is

              sent.  An  fuser process never kills itself, but may kill other fuser pro-

              cesses. The effective user ID of the process executing fuser is set to its

              real user ID before attempting to kill.

       -m     name specifies a file on a mounted file system or a block device  that  is

              mounted. All processes accessing files on that file system are listed.  If

              a directory file is specified, it is automatically changed  to  name/.  to

              use any file system that might be mounted on that directory.

三、数据库安装验证过程中出现的错误

Checking Network Configuration requirements ...
Actual Result: :java.lang.NullPointerException:Exception/Error Occurred
Check complete. The overall result of this check is: Not executed <<<<
Recommendation: Oracle supports installations on systems with DHCP-assigned public IP

addresses.  However, the primary network interface on the system should be configured with a

static IP address in order for the Oracle Software to function properly.  See the

Installation Guide for more details on installing the software on systems configured with

DHCP.

解决方法：添加主机认证

[root@vaxph97 ~]# vi /etc/hosts

# Do not remove the following line, or various programs

# that require network functionality will fail.

127.0.0.1               localhost.localdomain localhost

::1             localhost6.localdomain6 localhost6

192.168.1.97 vaxph97

四、导出指定数据对象（其中导出过程中需要转义）

其中单引号中的内容一定要用大写（上面的图片中写成了小写，因为不会排除这两个视图）

五、解决CENTOS上scp的安装问题

错误代码：

-bash: scp: command not found

解决方法：

配置YUM

输入yum install openssh-clients即可

六、解决expdp过程中ORA-28000和ORA-01017的错误

ora-28000错误为账户被锁，需要解锁账户（包括system账户）

解决方法：alter user system account unlock

ORA-01017为密码过期或不可用，更改密码即可

解决方案：alter user system identified by system

七、解决oracle库用户无法删除问题

1.可以现在数据库层面解决

解决方法

SQL> select username ,sid,serial# from v$session;

查出sid,serial#号

然后，通过数据库命令kill掉sid和serial#

SQL> alter system kill session 'sid,serial#';

2.如果kill不掉，可以通过系统命令来进行查询spid进程号

SQL> select p.username ,p.spid from v$session s ,v$process p where s.PADDR=p.addr and s.sid=147;

USERNAME             SPID

-------------------- ------------------------

oracle               18134

然后通过系统命令kill掉该进程

> kill -9 18134

3.如果仍然drop不掉用户，则可以将监听占时关闭，防止用户通过远程连接连接数据库

>lsnrctl stop