Setting Environmental Variables with oraenv Oracle Database Tips by Donald Burleson

Oracle provides a script called oraenv that can be used to change the environmental variables $ORACLE_HOME, $ORACLE_SID, and $PATHto allow a user to connect to a given database instance (a database instance is often referred to as a 'sID? or Oracle System Identifier). It can then be used again to switch to a different SID easily, even if the ORACLE_HOME for the new SID is different.

There are two methods for using the oraenv script. The first method is interactive, with the script asking the user to type in the SID. To make oraenv export the variables to the shell environment, it must be preceded with a period and a space as seen in Figure 6.5. 

The second method for using oraenv is non-interactive. This is done by setting the variables $ORAENV_ASK=NO and $ORACLE_SID=<sid> and then running the script with a period and space before it. This time, oraenv will not ask for the SID. It will use the one it finds in the variable $ORACLE_SID.  This non-interactive method is useful when calling oraenv from a script.

Figure 6.5 demonstrates using oraenv. The which command attempts to find the path to the dbca program. This command cannot find dbca in any of the directories identified by the $PATHvariable, and it reports the error. After running the oraenv script using * for the SID, the $PATH environmental variable is set properly and dbca is found.

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