Step 2: Set Operating System Environment Variables

Depending on your platform, you may have to set environment variables before starting SQL*Plus, or at least verify that they are set properly.

For example, on most platforms, you must set the environment variables ORACLE_SID and ORACLE_HOME. In addition, you must configure the PATH environment variable to include the ORACLE_HOME/bin directory. Some platforms may require additional environment variables:

• On UNIX and Linux, set environment variables by entering operating system commands.

• On Windows, Oracle Universal Installer (OUI) automatically assigns values to ORACLE_HOME and ORACLE_SID in the Windows registry.

If you did not create a database upon installation, OUI does not set ORACLE_SID in the registry; after you create your database at a later time, you must set the ORACLE_SID environment variable from a command window.

UNIX and Linux installations come with two scripts, oraenv and coraenv, that you can use to easily set environment variables. For more information, see Oracle Database Administrator's Reference for Linux and UNIX-Based Operating Systems.

For all platforms, when switching between instances with different Oracle homes, you must change the ORACLE_HOME environment variable. If multiple instances share the same Oracle home, then you must change only ORACLE_SID when switching instances.

Example 3-1 Setting Environment Variables in UNIX (C Shell)

setenv ORACLE_SID orcl
setenv ORACLE_HOME /u01/app/oracle/product/18.0.0/db_1
setenv LD_LIBRARY_PATH $ORACLE_HOME/lib:/usr/lib:/usr/dt/lib:/usr/openwin/lib:/usr/ccs/lib

Example 3-2 Setting Environment Variables in UNIX (Bash Shell)

export ORACLE_SID=orcl
export ORACLE_HOME=/u01/app/oracle/product/18.0.0/db_1
export LD_LIBRARY_PATH=$ORACLE_HOME/lib:/usr/lib:/usr/dt/lib:/usr/openwin/lib:/usr/ccs/lib

Example 3-3 Setting Environment Variables in Windows

SET ORACLE_SID=orawin2

Example 3-3 assumes that ORACLE_HOME and ORACLE_SID are set in the registry but that you want to override the registry value of ORACLE_SID to connect to a different instance.

On Windows, environment variable values that you set in a command prompt window override the values in the registry.