0 |
##halt (shut down) |
1
|
Single user mode
|
2
|
Multiuser, without NFS (multi-user mode, but no network status) FS-->FileSystem
|
##3 | Full multiuser mode (multi-user full version mode) |
4 | unused (reserved mode) |
5 | X11 (User Interface Mode) |
6 | reboot (restart mode) |
id:3initdefault: The default runlevel is 3
Start starting the corresponding services and components with runlevel=3
Start to boot the public components by default or Service
Start loading the service corresponding to runlevel
- ##When the startup is completed, all services
##System services
You can use the chkconfig command to view the services of the current virtual machine.
- By viewing, you can know that different levels correspond to each service and confirm that it will start automatically during this boot.
- After the boot is completed, you need Use the service (CentOS6) Systemctl (CentOS7) command to control the opening or closing of the service
-
Auto-start service at boot
rc.local- (When this file has execution permission, it will be executed automatically after booting) First create the folder where the script is stored
- mkdir -p /usr/local/scriptsCreate a script file in the folder
- vi hello.sh
- Give execution permission
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Go to the /etc/rc.d/rc.local file and add the absolute path to the script
Give rc.local execution permissions
##chkconfig
- First cancel the execution permission of rc.local, and then start testing
chmod a-x rc.local
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-
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Create automatic startup at boot Script file
vi schoolntpdate.sh
#!/bin/bash
#chkconfig:2345 88 99
#description:schoolntpdate.sh
## 开机自启动同步时间
yum info ntp && ntpdate cn.ntp.org.cn
- Set execution permissions
chmod a+x schoolnptdate.sh
-
- Copy the script to /etc/init.d directory
cp schoolntpdate.sh /etc/init.d/
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chkconfig --add /etc/init.d/schoolntpdate.sh
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reboot
## Scheduled taskIn the system service center, crond is responsible for periodic tasks
systemctl status crond.service
-
Add tasks and edit the current user’s task list-
crontab -e
星 星 星 星 星 command
分 时 日 月 周 命令
第一列表示分钟1~59 每分钟用*或者*/1表示
第二列表示小时1~23(0表示0点)
第三列表示日期1~31
第四列表示月份1~12
第五列标识号星期0~6(0表示星期天)
第六列表示要运行的命令
*: 表示任何时间都,实际上就是“每”的意思。可以代表00-23小时或者00-12每月或者00-59分
-: 表示区间,是一个范围,00 17-19 * * * cmd,就是每天17,18,19的整点执行命令
,: 是分割时段,30 3,19,21 * * * cmd,就是每天凌晨3和晚上19,21的半点时刻执行命令
/n: 表示分割,可以看成除法,*/5 * * * * cmd,每隔五分钟执行一次
30 21 * * * /usr/local/rc.d/Lighttpd restart
#上面的例子表示每晚21:30重启apache
45 4 1,10,22 * * /usr/local/rc.d/Lighttpd restart
#上面的例子表示每月1,10,22日的4:45重启apache
10 1 * * 6,0 /usr/local/rc.d/Lighttpd restart
#上面的例子表示周六、周日的1:10重启apache
0,30 18-23 * * * /usr/local/rc.d/Lighttpd restart
#上面的例子表示每天的18:00至23:0每隔30分钟重启apache
0 23 * * 6 /usr/local/rc.d/Lighttpd restart
#上面的例子表示每星期六的11:00重启apache
* */2 * * * /usr/local/rc.d/Lighttpd restart
#上面的例子表示每两小时重启apache
* 23-7/1 * * * /usr/local/rc.d/Lighttpd restart
#上面的例子表示晚上的11点到早上的7点之间,每隔一小时重启apache
0 21 4 * mon-wed /usr/local/rc.d/Lighttpd restart
#上面的例子表示每月的4号与每周一到周三的11点重启apache
0 4 1 jan * /usr/local/rc.d/Lighttpd restart
#上面的例子表示一月一号的4:00重启apache
--(功能描述:显示年月日时分秒)
date "+%Y %m %d %H %M %S"
Restart crontab to make the configuration take effect-
systemctl restart crond.service
View the current scheduled task through crontab -l-
View the history of the task-
vi /var/spool/mail/root
crontab -r
Test- Create a script that creates a folder
#!/bin/bash
dname=`date "+%Y%m%d%H%M%S"`
mkdir -p ~/$dname
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-
- Add a scheduled task and create a folder every minute
crontab -e #编辑定时任务
- #
systemctl restart crond.service #重启生效
-
crontab -l #查看当前的定时任务
-
-
- Check if created
-
Related recommendations: "Linux Video Tutorial"