请不要把备份脚本也放到backup_dir下，加到crontab里定时运行

#!/bin/sh  
export ORACLE_HOME=/u01/app/oracle/product/10.2.0/db_1    
export ORACLE_SID=orcl    
export NLS_LANG=AMERICAN_AMERICA.ZHS16GBK   
export PATH=/usr/lib64/qt-3.3/bin:/usr/local/bin:/bin:/usr/bin:/usr/local/sbin:/usr/sbin:/sbin:/home/oracle/bin:/u01/app/oracle/product/10.2.0/db_1/bin    
export BACKUP_DIR=/orabackup    
export NOW=$(date '+%Y%d%m')    
exp system/system@ORACLE_SID file=$BACKUP_DIR/system$NOW.dmp  log=$BACKUP_DIR/system$NOW.log full=y    
cd $BACKUP_DIR    
tar zcvf system$NOW.tar.gz system$NOW.dmp system$NOW.log --remove-files  
find /orabackup/ -mtime +7 -exec /bin/rm -rf '{}' \;

这个脚本是把system用户数据备份，然后压缩成TAR包，再删除备份目录下大于7天的文件