Linux之计划任务
计划任务特性
1. 需要在指定的某时间段运行
2. 需要将任务结果邮件通知用户
3. 单次任务及循环任务区别
Linux计划任务的实现工具
1. at工具
- 其只能执行一次性任务
- 其会自动加载部分环境变量
- 可以执行命令
- 可以执行脚本
- 作业有队列,用单字母表示,默认为a队列
- 作业计划任务是以绝对序列值进行排序
- 任务结果会以邮件的形式通知用户
2. batch工具
- 其使用方法与at工具类似
- 最大的区别为:它会选择系统在比较空闲的时间段执行任务
3. crontab命令
- 其可以循环执行任务,实现周期性任务
- 最小时间单位为
分钟
,如果需要到秒
级别,需要你是用外部机制 - 可以执行命令
- 可以执行脚本
- 每次的任务都会发送邮件至用户通知
- 其依赖于crond守护进程及相关辅助工具,
cronie
是其主程序包
一、at工具
synopsis: at [OPTIONS]...time
[time]
格式HH:MM[YYYY-mm-dd]
- 20:10 2015-10-30
noon
: 正午midnight
: 午夜teatime
: 下午4点tomorrow
: 明天now +# UNIT
* UNIT: min,hours,days,weeks
[options]
-l
: 列出任务队列,相当于atq
命令-f FILE
: 从指定文件中读取作业任务,不用交互式输入at -f at.sh now+5min
-d #
: 删除任务at -d 3
==atrm 3
:删除第3号任务
-c #
: 查看指定任务的内容-q a|b|c|d
: 指定默认队列
二、crontab工具
cron任务的分类
- 系统cron任务
- 配置文件
- /etc/crontab
- 配置命令
- 直接编辑/etc/crontab文件
- 配置文件
- 用户cron任务(
root用户也不例外
)- 配置文件
- /var/spool/cron/USERNAME
- 配置命令
- crontab -e
- 配置文件
/etc/crontab文件的格式
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" alt="" />
每一行定义一个周期性任务
此处的环境变量不同于用户登录后获得的环境,因此,建议命令使用绝对路径,或自定义path环境变量
执行结果邮件发送给想着用户,即mailto=中定义的用户
普通用户不需要定义mailto参数,因为他的任务文件就以用户名命名
共7个字段
如果命令中有%这类的符号,需要转义,但旋转到单引号中的不用转义
crontab命令:
synopsis - crontab [-u user] [-l | -r | -e] [-i] [-s]
[options]
-e : 编辑任务,建议使用crontab -e,这样可以帮忙检查其错误
-l : 列出所有任务
-r : 移除所有任务,即删除对应/var/spool/cron/USERNAME文件
-i : 交互式,在使用-r删除所有用户时,提示用户确认
-u USER : root用户可以为指定的用户管理、指定任务
注意:运行结果会以邮件方式通知当前用户,如果拒绝接收邮件,可以会导致未备份成功却没有任何消息反馈的情况,建设如下操作:
COMMAND > /dev/null : 将正确结果删除,只返回错误输出并发送邮件至用户
COMMAND &> /dev/null : 不建议此操作
指定的某任务在指定的时间因关机未能执行,下次开机不会自动执行
如果某时间点因故未能按时执行,下次开机后无论是否到了相应时间点,都要补充执行一次,可使用anacron实现
每12小时备份一次/etc目录至/backups目录中,保存格式为etc-yyy-mm-dd-hh.tar.xz”
01 */12 * * * root tar Jcf /backups/etc-$(date +"\%F-\%H-\%S").tar.xz /etc/
每周2、4、7备份/var/log/secure文件至/logs目录中,文件名格式为 secure-yyyymmdd
01 09 * * 2,4,7 root tar Jcf /logs/secure-$(date +"\%Y\%m\%d") /var/log/secure
每两个小时取当前系统/proc/meminfo文件中以S或M开头的行信息追加至/tmp/meminfo.txt文件中
01 */2 * * * root grep '^[M\|S]' /proc/meminfo > /tmp/meminfo.txt
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