1.安装crontab软件包：
  #yum install crontabs -y
  2.新建备份脚本：
  #vi /tmp/backup.sh，脚本内容如下:
  d_bak="/tmp/ovirt_engine_backup/`date +%Y%m%d_%H%M%S`"
  f_log="/tmp/rsync_ovirt_bak.txt"
  [ -d ${d_bak} ] || mkdir -p ${d_bak}
  cd ${d_bak}
  engine-backup --mode=backup --file=ovirt-engine.bak --log=backup.log >${f_log} 2>&1
  3.添加脚本执行权限：
  #chmod 777 /tmp/backup.sh
  4.添加定时任务：
  vi /etc/crontab:
  SHELL=/bin/bash
  PATH=/sbin:/bin:/usr/sbin:/usr/bin
  MAILTO=root
  # For details see man 4 crontabs
  # Example of job definition:
  # .---------------- minute (0 - 59)
  # |  .------------- hour (0 - 23)
  # |  |  .---------- day of month (1 - 31)
  # |  |  |  .------- month (1 - 12) OR jan,feb,mar,apr ...
  # |  |  |  |  .---- day of week (0 - 6) (Sunday=0 or 7) OR sun,mon,tue,wed,thu,fri,sat
  # |  |  |  |  |
  # *  *  *  *  * user-name  command to be executed
  47 10 * * * root /tmp/backup.sh
  
  5.启动定时任务服务：
  #systemctl enable crond
  #systemctl  restart crond