Centos 6,7 及Debian 下的 crontab 安装使用

安装crontab

Centos 6,7 下的安装

Centos 6,7 下 crontab 的安装有所区别， 用下面的命令安装：

在 CentOS 7 环境下你需要安装 cronie:

yum install cronie

在 CentOS 6 环境下需要安装 vixie-cron和 cronie:

yum install vixie-cron

和

yum install cronie

这两个命令的结果是一样的:

.../...
==================================================================
 Package         Arch       Version         Repository      Size
==================================================================
Installing:
 cronie          x86_64     1.4.4-12.el6    base             73 k
Installing for dependencies:
 cronie-anacron  x86_64     1.4.4-12.el6    base             30 k
 crontabs        noarch     1.10-33.el6     base             10 k
 exim            x86_64     4.72-6.el6      epel            1.2 M

Transaction Summary
==================================================================
Install       4 Package(s)

打开cron:

service crond start

/bin/systemctl start crond.service

要使它开机自启:

chkconfig crond on    //centos 6

systemctl enable crond.service    //centos 7

Debian 下的安装没那么多坑：

apt-get install cron

编辑定时任务配置

crontab -e

在打开的配置文件中加入：

0 3 * * * /sbin/reboot

表示每天凌晨3点0分系统重启

其他例子：

# 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)
# |  |  |      |  |
# *  *  *      *  *   command to be executed
  0  0  */2    *  *   command1
  0  0  2-31/2 *  *   command2
  *  *  */2    *  *   command3

command1 will be executed at 00:00 on every odd-numbered day (default range with step 2, i.e. 1,3,5,7,...,31)

command2 will be executed at 00:00 on every even-numbered day (i.e. 2,4,6,8,...,30)

command3 is an often made mistake. This will run on every minute of every odd-numbered day.

Note: It should be understood that in this approach command1 will run on both January 31st and February 1st (2 consecutive days)

Note: It should be understood that in this approach command2 will skip both January 31st and February 1st and will run only 3 days later.

ctrl+c，:wq 保存退出

重启程序:

/etc/rc.d/init.d/crond stop    //centos 6
/etc/rc.d/init.d/crond restart    //centos 6
service crond restart       
/bin/systemctl restart crond.service    //centos 7

debian下：
/etc/init.d/cron restart   

Ok, 完成！