ORA-00205: ERROR IN IDENTIFYING CONTROL FILE

ERROR

Error in Alertlog file:

ORACLE_BASE not set in environment. It is recommended
that ORACLE_BASE be set in the environment
Thu Mar 12 10:15:15 2015
alter database mount
ORA-00210: cannot open the specified control file
ORA-00202: control file: ‘/u01/apps/db/apps_st/data/cntrl03.dbf’
ORA-27037: unable to obtain file status
Linux Error: 2: No such file or directory

SOLUTION

set the ORACLE_BASE, also verify SID and ORACLE_HOME are set it correctly.

export ORACLE_BASE=/u01/apps