In a Ubuntu machine hosting a postgresql database, I have 16G space taken up at `/var/lib/postgresql/9.3/main/pg_log`. Apparently, log files from many months ago are being stored as well. I manually deleted a few to get rid of my `disk full` error. What's a robust way to delete old postgresql logs every week? Anything I can do in `postgresql.conf` to automate this process?

Currently I have the following in `postgresql.conf`:

```
#log_truncate_on_rotation = off         # If on, an existing log file with the
                                        # same name as the new log file will be
                                        # truncated rather than appended to.
                                        # But such truncation only occurs on
                                        # time-driven rotation, not on restarts
                                        # or size-driven rotation.  Default is
                                        # off, meaning append to existing files
                                        # in all cases.
#log_rotation_age = 1d                  # Automatic rotation of logfiles will
                                        # happen after that time.  0 disables.
log_rotation_size = 100MB               # Automatic rotation of logfiles will
                                        # happen after that much log output.
                                        # 0 disables.

```

I'm thinking I'll enable `log_rotation_age` and set its value to `30d`. But will this auto delete older log files?