[oracle@dg1 ~]$ vi .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
unset USERNAME

export EDITOR=vi
export ORACLE_SID=dg1
export ORACLE_BASE=/u01/app/oracle
export ORACLE_HOME=$ORACLE_BASE/product/10.2.0/db_1
export LD_LIBRARY_PATH=$ORACLE_HOME/lib:/usr/lib
export PATH=/u01/app/oracle/product/10.2.0/db_1/bin:/bin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/X11R6/bin
export PATH=$ORACLE_HOME/bin:$PATH
umask 022

解决方法：

[oracle@dg1 ~]$ sqlplus /nolog
bash: sqlplus: command not found
[oracle@dg1 ~]$ ln -s $ORACLE_HOME/bin/sqlplus /usr/bin
ln: creating symbolic link `/usr/bin/sqlplus' to `/bin/sqlplus': Permission deni ed
[oracle@dg1 ~]$ su - root
Password:
[root@dg1 ~]# ln -s $ORACLE_HOME/bin/sqlplus /usr/bin
[root@dg1 ~]# su - oracle
[oracle@dg1 ~]$ sqlplus /nolog

SQL*Plus: Release 10.2.0.1.0 - Production on Mon May 11 12:51:24 2009

Copyright (c) 1982, 2005, Oracle.  All rights reserved.

SQL> conn / as sysdba
Connected to an idle instance.
SQL> startup
ORACLE instance started.

Total System Global Area  167772160 bytes
Fixed Size                  1218316 bytes
Variable Size              79694068 bytes
Database Buffers           83886080 bytes
Redo Buffers                2973696 bytes
Database mounted.
Database opened.
SQL>