crontab -e 编辑定时脚本
    16 04 * su - oracle -c /home/oracle/export.sh > /home/oracle/backup/export.log 2>&1

    bash脚本内容
    #!/bin/bash
    DATE=date +%u
    ORACLEHOME=/opt/oracle/product/OraHome; export ORACLE_HOME
    NLS_LANG=american_america.zhs16gbk ; export NLS_LANG
    cd /home/oracle/backup/
    exp haha/haha1234 file=haha    $DATE.dmp log=haha$DATE.log owner=haha
    文件格式必须是exp要不然容易冲突
    exp system/oracle_123 file=expdpdb    $DATE.dmp log=expdpdb_$DATE.log owner=system