Setting OS Variables for Oracle database12c
In Linux/Unix, when you’re using the Bourne, Bash, or Korn shell, you can set OS variables manually from the OS
$ export ORACLE_HOME=/u01/app/oracle/product/12.1.0.1/db_1
$ export ORACLE_SID=o12c
$ export LD_LIBRARY_PATH=/usr/lib:$ORACLE_HOME/lib
$ export PATH=$ORACLE_HOME/bin:$PATH