Linux定时执行脚本

0.版本说明

环境：centos7.9
版本：crontabs

1.安装

执行以下命令，查看本机是否已安装crontabs

service crond status

返回结果如下表示已安装

[root@host-10-10-10-14 /]# service crond status
Redirecting to /bin/systemctl status crond.service
● crond.service - Command Scheduler
   Loaded: loaded (/usr/lib/systemd/system/crond.service; enabled; vendor preset: enabled)
   Active: active (running) since Tue 2023-05-30 16:39:55 CST; 5min ago
 Main PID: 408 (crond)
   CGroup: /system.slice/crond.service
           └─408 /usr/sbin/crond -n

May 30 16:39:55 host-10-10-10-14 systemd[1]: Started Command Scheduler.
May 30 16:39:55 host-10-10-10-14 crond[408]: (CRON) INFO (RANDOM_DELAY will be scaled with factor 88% if used.)
May 30 16:39:55 host-10-10-10-14 crond[408]: (CRON) INFO (running with inotify support)
May 30 16:39:55 host-10-10-10-14 crond[408]: (CRON) INFO (@reboot jobs will be run at computer's startup.)
May 30 16:40:01 host-10-10-10-14 crond[408]: /usr/sbin/sendmail: error while loading shared libraries: libmysqlclient.so.18: cannot open shared object file: N... directory
May 30 16:41:01 host-10-10-10-14 crond[408]: /usr/sbin/sendmail: error while loading shared libraries: libmysqlclient.so.18: cannot open shared object file: N... directory
May 30 16:42:01 host-10-10-10-14 crond[408]: /usr/sbin/sendmail: error while loading shared libraries: libmysqlclient.so.18: cannot open shared object file: N... directory
May 30 16:43:01 host-10-10-10-14 crond[408]: (root) RELOAD (/var/spool/cron/root)
Hint: Some lines were ellipsized, use -l to show in full.

如果未安装，执行以下命令安装

yum install vixie-cron crontabs
yum install crontabs

安装完之后，启动crontabs

service crond start

再次执行以下命令查看安装状态

service crond status

设置开机自启动

chkconfig crond on

2.配置定时任务

输入以下命令进行定时任务编辑

crontab -e

输入i进入编辑状态，回车后在第一行输入执行定时任务的代码，按esc退出编辑模式后按:wq保存并退出

1 0 * * * sh /opt/logs/backup.sh

重启crond使改动生效

service crond restart

输入以下命令查看已经添加的任务调度

crontab -l

3.crontab 自定义执行时间

基础格式，定点执行

* * * * * command

以下一些例子
每个小时的第30分钟执行

30 * * * * sh /opt/logs/backup.sh

每天12点30分的时候执行

30 12 * * * sh /opt/logs/backup.sh

每月第5天12点30分的时候执行

30 12 5 * * sh /opt/logs/backup.sh

[逗号]代表不连续的时间
每小时的第5，10，15分钟执行

5,10,15 * * * * sh /opt/logs/backup.sh

[-]代表连续的时间范围
每天的5-8小时的20分时执行

20 5-8 * * * sh /opt/logs/backup.sh

*/n 代表每隔多久执行一次
每分钟执行一次

*/1 * * * * sh /opt/logs/backup.sh

4.结束语

本篇只记录自己的学习过程，更好的提升自己