how to permanently change environment variables in oracle database

The below are the steps:

1. Shutdown the database instance for which the env variable has to be changed.
2. Backup $HOME/.cshrc file.
3. Change the value of the required env variable to the desired value in $HOME/.cshrc file.
4. Logout and login again from the OS user which is the corresponding SYS user in database. in my case, it is oracle user.
5. Startup the database instance.

In my case, the value of ORACLE_BASE parameter which is showing in pfile(after creating it from spfile) was incorrect. i had to change it using below above procedure.

Regards

Vineet Arneja