今天登录一台服务器用roote用户登录的,在切换到oracle用户，执行sqlplus sys/ as sysdba进入数据库提示如下错误：
SP2-0750: You may need to set ORACLE_HOME to your Oracle software directory
在/home/oracle目录下查看文件.bash_profile，它是隐藏文件。
$ 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 PATH
export ORACLE_BASE=/u01/app/oracle
export ORACLE_HOME=/u01/app/oracle/product/11.1.0/db_1
export ORACLE_SID=orcl
export PATH=$ORACLE_HOME/bin:$PATH
export LD_LIBRARY_PATH=$ORACLE_HOME/lib
LANG=zh_CN.UTF-8; export LANG
NLS_LANG='SIMPLIFIED CHINESE_CHINA.AL32UTF8'; export NLS_LANG[oracle@localhost ~]$ cd $ORACLE_HOME
-bash: cd: /u01/app/oracle/product/11.1.0/db_1: 没有那个文件或目录
发现oracle安装定义的家目录是在/u01/app/oracle/product/11.1.0/db_1目录下的
u01目录是root用户的权限，在切回到root用户，执行如下命令：
[root@localhost ~]# cd $ORACLE_HOME
[root@localhost dbhome_1]# pwd
/u01/app/oracle/product/11.2.0/dbhome_1
[root@localhost dbhome_1]# sqlplus / as sysdba
或是
[root@localhost dbhome_1]# cd bin
[root@localhost dbhome_1]# pwd
/u01/app/oracle/product/11.2.0/dbhome_1/bin
[root@localhost bin]# ./sqlplus / as sysdba
SQL*Plus: Release 11.2.0.4.0 Production on Thu Oct 12 17:20:48 2017
Copyright (c) 1982, 2013, Oracle. All rights reserved.
Enter password:
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL>问题解决！
