在LINUX下循环备份的方法

备份是我们常需要做的事, 你可以在服务器上有一个文件夹专门用于存放备份.然后定期删除(可以是一个脚本定期执行),这样就比较麻烦,因为如果你想每次删除比较旧的备份, 你就得对备份进行时间倒序.

其实可以完全利用LINUX下的 date命令来生成想要的文件名用于备份.比如你想保留过去的 24 小时备份,那么,你可以用:

1 2	H=`date +"%H"` ls > backup_$H # your backup command (e.g. mysqldump)

H=`date +"%H"`
ls > backup_$H  # your backup command (e.g. mysqldump)

来生成类似 backup_0, backup_1, .. backup_23 之类的文件名.对应过去24 小时每小时的备份.同时,你的 Crontab 必须设置成每小时运行一次.这样就省事许多,因为每一时间最多就 24 个备份,新的会复盖掉24小时前的老备份.也不必担心硬盘爆掉.

同样的, 可以配合 crontab 来保留过去7天的备份,过去30天的备份等等.核心就是这个 date 命令,生成的文件名的相关参数是:

  %%   a literal %
  %a   locale's abbreviated weekday name (e.g., Sun)
  %A   locale's full weekday name (e.g., Sunday)
  %b   locale's abbreviated month name (e.g., Jan)
  %B   locale's full month name (e.g., January)
  %c   locale's date and time (e.g., Thu Mar  3 23:05:25 2005)
  %C   century; like %Y, except omit last two digits (e.g., 20)
  %d   day of month (e.g., 01)
  %D   date; same as %m/%d/%y
  %e   day of month, space padded; same as %_d
  %F   full date; same as %Y-%m-%d
  %g   last two digits of year of ISO week number (see %G)
  %G   year of ISO week number (see %V); normally useful only with %V
  %h   same as %b
  %H   hour (00.23)
  %I   hour (01.12)
  %j   day of year (001.366)
  %k   hour, space padded ( 0.23); same as %_H
  %l   hour, space padded ( 1.12); same as %_I
  %m   month (01.12)
  %M   minute (00.59)
  %n   a newline
  %N   nanoseconds (000000000.999999999)
  %p   locale's equivalent of either AM or PM; blank if not known
  %P   like %p, but lower case
  %r   locale's 12-hour clock time (e.g., 11:11:04 PM)
  %R   24-hour hour and minute; same as %H:%M
  %s   seconds since 1970-01-01 00:00:00 UTC
  %S   second (00.60)
  %t   a tab
  %T   time; same as %H:%M:%S
  %u   day of week (1.7); 1 is Monday
  %U   week number of year, with Sunday as first day of week (00.53)
  %V   ISO week number, with Monday as first day of week (01.53)
  %w   day of week (0.6); 0 is Sunday
  %W   week number of year, with Monday as first day of week (00.53)
  %x   locale's date representation (e.g., 12/31/99)
  %X   locale's time representation (e.g., 23:13:48)
  %y   last two digits of year (00.99)
  %Y   year
  %z   +hhmm numeric time zone (e.g., -0400)
  %:z  +hh:mm numeric time zone (e.g., -04:00)
  %::z  +hh:mm:ss numeric time zone (e.g., -04:00:00)
  %:::z  numeric time zone with : to necessary precision (e.g., -04, +05:30)
  %Z   alphabetic time zone abbreviation (e.g., EDT)

比如,保留过去 30 天的备份,那么可以用: