[oracle@db1 ~]$ ps -ef |grep ora_
oracle 11821 1 0 09:52 00:00:00 ora_q002_zddb1
oracle 17047 1 0 May27 00:00:13 ora_j002_zddb1
oracle 17935 1 0 May28 00:00:01 ora_j001_zddb1
oracle 18755 1 0 May28 00:00:00 ora_pz98_zddb1
oracle 20089 1 0 May27 00:00:01 ora_pmon_zddb1
oracle 20091 1 0 May27 00:00:00 ora_diag_zddb1
oracle 20093 1 0 May27 00:00:00 ora_psp0_zddb1
oracle 20095 1 0 May27 00:00:03 ora_lmon_zddb1
oracle 20097 1 0 May27 00:00:09 ora_lmd0_zddb1
oracle 20100 1 0 May27 00:00:11 ora_lms0_zddb1
oracle 20104 1 0 May27 00:00:13 ora_lms1_zddb1
oracle 20108 1 0 May27 00:00:00 ora_mman_zddb1
oracle 20110 1 0 May27 00:00:04 ora_dbw0_zddb1
oracle 20112 1 0 May27 00:00:06 ora_lgwr_zddb1
oracle 20114 1 0 May27 00:00:16 ora_ckpt_zddb1
oracle 20116 1 0 May27 00:00:05 ora_smon_zddb1
oracle 20118 1 0 May27 00:00:00 ora_reco_zddb1
oracle 20120 1 0 May27 00:00:41 ora_cjq0_zddb1
oracle 20122 1 0 May27 00:00:10 ora_mmon_zddb1
oracle 20124 1 0 May27 00:00:11 ora_mmnl_zddb1
oracle 20126 1 0 May27 00:00:00 ora_d000_zddb1
oracle 20128 1 0 May27 00:00:00 ora_s000_zddb1
oracle 20137 1 0 May27 00:00:09 ora_lck0_zddb1
oracle 20201 1 0 May27 00:00:00 ora_arc0_zddb1
oracle 20203 1 0 May27 00:00:01 ora_arc1_zddb1
oracle 20229 1 0 May27 00:00:22 ora_pz99_zddb1
oracle 20265 1 0 May27 00:00:00 ora_qmnc_zddb1
oracle 20301 1 0 May27 00:00:47 ora_j000_zddb1
oracle 20404 1 0 May27 00:00:06 ora_q000_zddb1
oracle 24015 23925 0 10:19 pts/5 00:00:00 grep ora_
[oracle@db1 ~]$
//数据库运行正常，通过Listeners能够正常连接。
[root@db1 ~]# export ORACLE_HOME=/u01/app/oracle/product/10.2.0/db_1/
[root@db1 ~]# export ORACLE_SID=zddb1
[root@db1 ~]# sqlplus
-bash: sqlplus: command not found
[root@db1 ~]# /u01/app/oracle/product/10.2.0/db_1/bin/sqlplus "/ as sysdba"
SQL*Plus: Release 10.2.0.4.0 - Production on Fri May 29 09:58:12 2009
Copyright (c) 1982, 2007, Oracle. All Rights Reserved.
ERROR:
ORA-01031: insufficient privileges
Enter user-name:
ERROR:
ORA-01017: invalid username/password; logon denied
//root用户连接结果正常
[root@db1 ~]# su - oracle
[oracle@db1 ~]$ export ORACLE_SID=zddb1
[oracle@db1 ~]$ export ORACLE_HOME=/u01/app/oracle/product/10.2.0/db_1/
[oracle@db1 ~]$ /u01/app/oracle/product/10.2.0/db_1/bin/sqlplus "/ as sysdba"
SQL*Plus: Release 10.2.0.4.0 - Production on Fri May 29 09:59:03 2009
Copyright (c) 1982, 2007, Oracle. All Rights Reserved.
Connected to an idle instance.
SQL>
//Oracle用户连接结果异常
问题分析：
在Oracle数据库系统中，用户如果要以特权用户身份（SYSDBA／SYSOPER）登录Oracle数据库可以有两种身份验证的方法： 即使用与操作系统集成的身份验证或使用Oracle数据库的密码文件进行身份验证。因root用户因不在dba组，显示权限不足，结果是正常的，但Oracle用户应该可以使用sysdba的身份登陆到数据库中，但却显示：“Connected to an idle instance. ” ，即不能登陆到数据库中。但从操作系统中查看，使用网络连接方式，却可以连接。排除了tnsnames.ora配置错误，问题比较奇怪。
通过网友的提醒发现环境变量设置出现问题
[oracle@db1 ~]$ cat .bash_profile
# .bash_profile# Get the aliases and functions
if [ -f ~/.bashrc ]; then
. ~/.bashrc
fi
# User specific environment and startup programs
PATH=$PATH:$HOME/bin
export ORACLE_BASE=/u01/a