I am not able to use the sqlplus after intalling 11g on redhat 6.7
This should sort you out. Remember to login &amp; out again once edited, or do a . .bash_profile to source it. Also, make sure it's executable (chmod u+x ~/.bash_profile ).

PATH=$PATH:$HOME/bin
TMP=/tmp
ORACLE_HOSTNAME=prashant.localdomain
ORACLE_UNQNAME=prod
ORACLE_BASE=/u01/app/oracle
ORACLE_HOME=$ORACLE_BASE/product/11.2.0/dbhome_1
ORACLE_SID=prod
PATH=$ORACLE_HOME/bin:$PATH:/usr/sbin:/sbin

export TMP ORACLE_HOSTNAME ORACLE_UNQNAME ORACLE_BASE ORACLE_HOME ORACLE_SID PATH


The most glaring error was that you were nuking PATH by doing PATH=$ORACLE_HOME/bin:PATH; - there was a $ missing.