Is it save to simply delete oldest records from Listener.log file? Or what is the best way to clean this file up?
It is safe as long as you don't see any problem in it, I mean, if you are not running problem with you network config.
Some people change the log file in the lsnrctl to compress and backup it, I simply erase all the file rows but the last 10.
Ramon Caballero, DBA, email@example.com
You can rename the file and keep it for historical purposes for some time.
Or if you don't need any more info from this, you can safely delete the file as well.
It will create a new file when the original is not there.
In my system, the way we do it is we, roll this log every month and then keep the last 2 months of information and delete the rest. It all depends how much you consider valuable the information is.
Life is a journey, not a destination!