Behaviors of SQL*Plus are also controlled a some environment variables predefined on the local operating system. Here are some commonly used SQL*Plus environment variables:

* ORACLE_HOME - The home directory where your Oracle client application is installed.

* PATH - A list of directories where SQL*Plus will search for executable or DLL files. PATH should include $ORACLE_HOMEin.

* SQLPLUS - The directory where localization messages are stored. SQLPLUS should be set to $ORACLE_HOMEsqlplusmesg

* TNS_ADMIN - The directory where the connect identifier file, tnsnames.ora is located. TNS_ADMIN should be set to $ORACLE_HOME/network/admin.