停止 Cron 作业重叠的代码 [英] Code for stopping the overlapping of the Cron job

问题描述

我需要停止 cron 作业的重叠，例如:如果一个 cron 作业安排在早上 2 点钟进行数据库备份，而其他 cron 作业安排在早上 7 点钟进行数据库备份.所以我需要停止如果 2 点钟的 DB 备份未完成，则 7 点钟计划的 cron 作业.

I need to stop the overlapping of cron jobs for example:If a cron job is scheduled at morning 2 o clock for DB backup and other cron job is scheduled at morning 7 o clock for DB backup again.So i need to stop the 7 o clock scheduled cron job if the DB backup for 2 o clock is not completed.

推荐答案

这就是 flock 的用途.来自man flock:

This is what flock is for. From man flock:

...
The  third form is convenient inside shell scripts, and is usually used
       the following manner:

       (
         flock -n 9 || exit 1
         # ... commands executed under lock ...
       ) 9>/var/lock/mylockfile
...

在这种情况下，flock 将尝试为 /var/lock/myfile 获取 fd 9 上的锁定.如果不能(因为之前的作业仍在运行)，它将退出.

In this case, flock will try to get a lock on fd 9 for /var/lock/myfile. If it can't (because the earlier job is still running), it will exit.

您需要将其放入脚本中.

You need to put it in a script.

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