Oracle: Recycle listener.log
Oracle stores a log-file (listener.log) under $ORACLE_HOME/network/log that keeps track of all connections made to the database.
Oracle keeps this file as an open file-stream, so even if you rename the file, it still keeps on growing as new connections are made.
This method will let you recycle/truncate/purge listener.log without resorting to taking the listener down which would cause a disruption to users.
The idea is to turn log_status off, create a new file, then turn log_status on again
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$ lsnrctl set log_status off $ mv listener.log listener.log.old $ touch listener.log $ lsnrctl set log_status on