I can't find anything via google, or searching the archives of this
e-list, or in the docs.

I downloaded and installed the latest Linux RPM
(FirebirdCS-1.5.1.4481-0) onto my RedHat 9 laptop.

I changed the password to "masterkey" since I'm just doing local
development.

I added /opt/firebird/bin to my .bashrc. Whenever I try to access an
existing database (e.g. the example employee database), or create a
new database, I get the following error:

operating system directive open failed
-Permission denied

However, when I use root permissions, it works. For example:

$ isql -u sysdba -p masterkey /opt/firebird/examples/employee.fdb
Statement failed, SQLCODE = -902


operating system directive open failed
-Permission denied
Use CONNECT or CREATE DATABASE to specify a database
SQL> quit;
$ sudo isql -u sysdba -p masterkey /opt/firebird/examples/employee.fdb
Password:
Database: /opt/firebird/examples/employee.fdb, User: sysdba
SQL> quit;
$

- - - - - - - - - - -

Another example:

$ sudo isql -u sysdba -p masterkey
Use CONNECT or CREATE DATABASE to specify a database
SQL> create database '/tmp/root.ib';
SQL> quit;
$ isql -u sysdba -p masterkey
Use CONNECT or CREATE DATABASE to specify a database
SQL> create database '/tmp/user.ib';
Statement failed, SQLCODE = -902

operating system directive open failed
-Permission denied
SQL> quit;