> <<I'm trying to create a new database, but after typing the "create database" command followed by the path and filename, hitting Enter and then typing in my username and password (the only user is sysdba and I did change the password) I get the following error message:
> Statement failed, SQLSTATE = 08006
> Can not access lock files directory /tmp/firebird/>>
>
> [...]

It all depends on the path you provide in CREATE DATABASE. If it is just
a local filesystem path, e.g. CREATE DATABASE "/somefolder/dbname.fdb",
then the FB instance handling your request is running with your current
user account (somewhat like embedded FB).
So, try what the rest of the error message suggests and do:
CREATE DATABASE "localhost:/somefolder/dbname.fdb" USER "SYSDBA"
PASSWORD "yourpassword";
This way you access the FB server via the network stack and the request
gets handled by the FB inet server, running with "firebird" account
priviledges.

What I said, but better. Make sure somefolder has the privileges to allow
another user (firebird) to write to it and access it.

Regards
Paul