Monthly Archives: June 2015

Linux如何设置定时任务

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1、基本概念

crontab命令常见于Unix和类Unix的操作系统之中，用于设置周期性被执行的指令。该命令从标准输入设备读取指令，并将其存放于“crontab”文件中，以供之后读取和执行。crontab储存的指令被守护进程激活， crond常常在后台运行，每一分钟检查是否有预定的作业需要执行。这类作业一般称为cron jobs。

2、命令格式

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# 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

2.1、每月每天每小时的第 0 分钟执行一次 xxoo
0 * * * * xxoo

2.2、在 12 月份期间, 每天的早上 6 点到 12 点中，每隔 20 分钟执行一次 xxoo
*/20 6-12 * 12 * xxoo

2.3、周一到周五每天下午 5:00 xxoo
0 17 * * 1-5 xxoo

2.4、每月每天的午夜 0 点 20 分, 2 点 20 分, 4 点 20 分 xxoo
20 0-23/2 * * * xxoo

3、基本操作[……]

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Linux下添加新硬盘并挂载使用

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1、 查看新磁盘信息

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[root@Crayfish ~]# fdisk -l
 
Disk /dev/xvda: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00060953
 
    Device Boot      Start         End      Blocks   Id  System
/dev/xvda1   *           1        2611    20970496   83  Linux
 
Disk /dev/xvdb: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

2、硬盘分区

2.1、进入fdisk模式

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[root@Crayfish ~]# fdisk /dev/xvdb
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel with disk identifier 0xc233737d.
Changes will remain in memory only, until you decide to write them.
After that, of course, the previous content won't be recoverable.
 
Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)
 
WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
         switch off the mode (command 'c') and change display units to
         sectors (command 'u').

2.2、输入n进行分区
[……]

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