Both, in a read-only ORACLE_HOME and read/write ORACLE_HOME, the user-specific files, instance-specific files, and log files reside in a location known as the ORACLE_BASE_HOME.

In a read/write ORACLE_HOME, the ORACLE_BASE_HOME path is the same as the ORACLE_HOME directory. However, in a read-only ORACLE_HOME, the ORACLE_BASE_HOME directory is not co-located with ORACLE_HOME but is located at ORACLE_BASE/homes/HOME_NAME.

Where, HOME_NAME is the internal name for ORACLE_HOME.

For example, the networking directories network/admin, network/trace, and network/log are located in the ORACLE_BASE_HOME directory. In a read/write ORACLE_HOME the networking directories appear to be in ORACLE_HOME because ORACLE_BASE_HOME is co-located with ORACLE_HOME, whereas in a read-only ORACLE_HOME the networking directories are located in ORACLE_BASE/homes/HOME_NAME.

$ setenv ORACLE_HOME /u01/app/oracle/product/19.0.0/dbhome_1
$ cd $ORACLE_HOME/bin
$ ./orabasehome

$ ./orabasehome
/u01/app/oracle/homes/OraDB19Home1