The environment variables play a very important role to determine certain important things like:-
• OS where the software has to run
• Where will the Oracle will store the files.
• Which database will the Oracle connect to.
Some of the environment variables are as follows:-
ORACLE_BASE
This is the top most directory where all the Oracle files will be residing. Oracle creates a number of directories under this and uses them for tracking, purpose ,management and troubleshooting.
ORACLE_HOME
This is where actually you have installed Oracle.
It also tells your session regarding which Oracle installation you want to use.
If one have a number of or multiple Oracle installations on the same machine, one needs to set this variable to the location where you are actually working.
ORACLE_SID
This is actually set to the name of the database you are actually connecting to.
If currently you re not connected to any database you can use the name of the database you will be connecting to in future.
This variable is actually case sensitive in some of the OS and should usuallu be limited to 8 characters beginning with a letter.
PATH
This variable is usually set for all the variables in the system and if one is installing Oracle on a system one has to include the Oracle path too.
It is the responsibility of the OS to check the PATH variable sequentially to detect the tool which needs to be launched.
If the Oracle path is included in the path it helps the OS to launch the application to launch it even if there is a similar application with the same name.
Setting the environment with oraenv
As discussed above all the environment settings are stored in the OS user profile on UNIX/LINUX which are managed with the help of script in LINUX/UNIX environments.
On running the script it simply asks you what environment do you wish to connect to.
This script is called oraenv which helps in adapting to different oracle versions.