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How to understand the Linux anacron problem, in view of this problem, this article introduces the corresponding analysis and solutions in detail, hoping to help more partners who want to solve this problem to find a more simple and feasible way.

You cannot run Cron if you want to turn it off when you are not using it to save resources (common on desktops and laptops). If you cannot run Cron on a regular basis, a large number of log files will be generated and other problems will arise. The Anacron utility provides a solution that enables the computer to run regular maintenance jobs after each boot, even if the boot time is not fixed.

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If you are running Linux (or most other UNIX systems) on a desktop or laptop, you may shut down the system frequently. Indeed, some systems may take longer to shut down than turn on during the day. This can help reduce the electricity bill. For laptops, if you don't have an electrical outlet during the trip, turning it off often helps to prolong the life of the computer. Unfortunately, this frequent shutdown behavior can cause problems for Linux systems because Linux uses a utility called Cron to run daily maintenance jobs in the background. When these jobs stop running, they will cause problems, and over time, the performance of the system will be lower and lower.

Cron is designed to start the program at a specified time when no one is on duty. Generally speaking, there are two types of Cron jobs (that is, programs run by Cron): system Cron jobs, which are run by the system to perform system maintenance tasks, and user Cron jobs, which are created by users to perform user tasks. For these two types of jobs, the system Cron job is more important. These jobs may include cleaning up stale files in / tmp, replacing log files, updating spam filtering rules, and updating the locate database.

Most Linux systems contain a series of Cron-related subdirectories in / etc. The / etc/crontab file specifies which jobs Cron should run as system Cron jobs. Typically, this file tells Cron to run scripts located in / etc/cron.hourly, / etc/cron.daily, / etc/cron.weekly, and / etc/cron.monthly at hourly, daily, weekly, and monthly intervals, respectively. The exact time to run these jobs is specified in / etc/crontab. For jobs that run daily and at longer intervals, the run time is usually in the morning. The problem is that desktops and laptops are likely to be turned off at these times.

When Cron jobs fail to run, problems follow. Specific problems depend on the Cron job that should have been run, but for example, problems include larger log files, confusion in the / tmp directory, and out-of-date databases that store available software updates or the location of local system commands.

Obviously, it is important to keep running Cron jobs. If you need to shut down a system frequently, you should look for a way to avoid these problems. Anacron is the solution to achieve this goal.

This is the answer to the question about how to understand Linux anacron. I hope the above content can be of some help to you. If you still have a lot of doubts to solve, you can follow the industry information channel to learn more about it.

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