log files can get very big if not rotated at appropriate periods. logrotate is the tool that usually comes installed w/ Ubuntu boxes to do this for you.
Install logrotate
$ sudo apt-get install logrotate
Configuration
$ cat /etc/logrotate.conf
Usually you may not have to make any changes to this. Explanation for the fields can be see here. Or try man logrotate.
Application specific configurations
$ ls /etc/logrotate.d/
This folder is populated with config files from different applications even if logrotate is not installed on the machine. Example
$ cat /etc/logrotate.d/apache2
If apache2 is installed in the machine, you can see this file has the log rotate policy for all the apache log files.
Cron job
logrotate is not a daemon process. It is added a daily cron job. When everyday it is run, it checks all the log files defined in the config and updates the status file.
$ cat /var/lib/logrotate/status
When “appropriate” time has elapsed, it will create a new log file and rename the old file appropriately. It also gunzips the old file so that the disk space is saved. Its pretty neat and very simple to setup.