TO CONNECT USING SHELL SCRIPTING FROM ROOT USER (CRON TAB)
PATH=$PATH:$HOME/bin
export PATH
ORACLE_SID=orcl
ORACLE_BASE=/oracle/product/10.2.0
ORACLE_HOME=$ORACLE_BASE/db_1
PATH=$ORACLE_HOME/bin:$PATH
export ORACLE_SID ORACLE_BASE ORACLE_HOME PATH
sqlplus -s hr/hr@orcl @ /home/oracle/Desktop/a.sql