TWO TASK
From Oracle FAQ
TWO_TASK is an environment variable used to specify that connections should be made to a remote database (via SQL*Net) without specifying a service name (tnsnames.ora entry). This is equivalent to LOCAL registry entry on Windows platforms.
Windows:
set TWO_TASK=oraservice1
Unix/ Linux:
export TWO_TASK=oraservice1
Also, see TNS_ADMIN, ORACLE_HOME, ORACLE_SID and ORACLE_BASE.

