linux crontab命令

简介和原理:

    服务相关  

#从新加载服务
service crond reload
#从新启动服务
service crond restart

    编辑&查看crontab的命令

crontab -e -u cici
crontab - l

    linux 保存crontab的命令的位置

/var/spool/cron

    crontab 命令配置的位置<针对整个系统而言的配置>

/etc/crontab

 

HELL=/bin/bash
PATH=/sbin:/bin:/usr/sbin:/usr/bin
MAILTO=root 
//如果出现错误，或者有数据输出，
//数据作为邮件发给这个帐号 邮件路径是 /var/spool/mail/用户名
HOME=/ //使用者运行的路径,这里是根目录 

# 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

 

例子1:

1 定期任务：

•  定期执行如下语句: 1

cat /home/cici/Documents/2013_09_01.txt |tee -a /home/cici/Documents/showScreen_`date +\%Y-\%m-\%d_-\%H:\%M:\%S`.txt

#将2013_09_01.txt 文件中的内容输出到 showScreen_当前日期.txt文件中

 

•  将文件 2
  

  /home/cici/Documents/2013_09_01.txt

•    中的内容追加到下述文件中   /home/cici/Documents/2013_09_01_2.txt

2 编辑crontab 命令

[root@localhost Desktop]# su cici
[cici@localhost Desktop]$ crontab -e

*/1 * * * * sh /home/cici/cron/showSentenceToScreen.sh

3 登陆root用户,使crontab命令生效

[cici@localhost Desktop]$ su root
Password: 
[root@localhost Desktop]# service crond reload
Reloading crond:                                           [  OK  ]
[root@localhost Desktop]# 

 4 确定脚本文件有权执行

[cici@localhost Desktop]$ ll /home/cici/cron/showSentenceToScreen.sh
-rwxrwxrwx 1 cici cici 87 Aug 31 13:52 /home/cici/cron/showSentenceToScreen.sh

 5 检查执行结果

[cici@localhost Desktop]$ cat /home/cici/Documents/2013_09_01_2.txt

 每分钟都增加一行

 

6 参考资料

   tree命令

http://linux.chinaitlab.com/command/723466.html

   Crontab命令详解

http://blog.csdn.net/tianlesoftware/article/details/5315039

 

https://support.eapps.com/index.php?/Knowledgebase/Article/View/458/55/user-guide---cron-scheduler#adding_cron_jobs_basic_concepts  

例子2:

 批量执行某个文件夹下面脚本内容:

 

[cici@localhost mail]$ crontab -e
 */1 * * * run-parts /home/cici/cron
:wq
[cici@localhost mail]$ cd /home/cici/cron
[cici@localhost cron]$ vi showSentenceToScreen_1.sh

cat /home/cici/Documents/2013_09_01.txt |tee -a /home/cici/Documents/showScreen1_`date +\%Y-\%m-\%d_-\%H:\%M:\%S`.txt
:wq

[cici@localhost cron]$ vi showSentenceToScreen_2.sh

cat /home/cici/Documents/2013_09_02.txt |tee -a /home/cici/Documents/showScreen2_`date +\%Y-\%m-\%d_-\%H:\%M:\%S`.txt
:wq

[root@localhost Documents]# service crond restart
Stopping crond:                                            [  OK  ]
Starting crond:                                            [  OK  ]

注意：确保sh文件至少有读权限.

   

[cici@localhost cron]$ cd /home/cici/cron/
[cici@localhost cron]$ chmod 400 showSentenceToScreen_1.sh