for alert file,

find $ORACLE_BASE/admin/$ORACLE_SID/bdump -ctime +60 -name alert_$ORACLE_SID.log -exec rm {} \;

listener file,

find $ORACLE_HOME/network/log -name listener.log -ctime +14 -exec rm {} \;

sqlnet file,

find $ORACLE_HOME/network/log -name sqlnet.log -ctime +14 -exec rm {} \;