先检查下定时：
查看服务的状态 systemctl status 服务名
service crond status
To start the cron service, use:
/etc/init.d/crond start
/etc/init.d/crond stop
/etc/init.d/crond restart
OR RHEL/CentOS 5.x/6.x user:
service crond start
service crond stop
service crond restart
OR RHEL/Centos Linux 7.x user:
systemctl start crond.service
systemctl stop crond.service
systemctl restart crond.service
如果没有需要安装：
# yum install crontabs
登入服务器root用户，切换oracle用户下：
1、创建oracle用户的删除归档日志文件的shell：del_archlog.sh
#! /bin/bash
source ~/.bash_profile
LOG_DIR=/home/oracle/del_log/
TIME=`date '+%Y-%m-%d'`
LOG_NAME=${LOG_DIR}/${ORACLE_SID}_${TIME}".log"
$ORACLE_HOME/bin/rman log=$LOG_NAME target /<<EOF
crosscheck archivelog all;
delete noprompt expired archivelog all;
delete noprompt archivelog until time 'sysdate-1';
exit;
EOF
2、赋可执行权限
chmod +x /home/oracle/del_log/del_archlog.sh
3、设定定时任务，在Oracle用户下，编辑配置文件
crontab -e
配置文件内容：
标记为每天六点六分进行定时删除日志文件
6 6 * * * /home/oracle/del_log/del_archlog.sh
