How to use crontab to accurately control tasks to execute loops within a specified time period?

Use crontab and shell scripts to achieve precise control of timing tasks

Many users need to perform tasks at a fixed frequency over a specific time range. This article will introduce in detail how to use crontab and shell scripts to accurately control tasks to execute loops within a specified time period.

Suppose we need to perform tasks every 8 minutes between 21:30 and 22:30 pm. The minute and hour fields of crontab are not accurately controlled by using the start and end times. crontab is better at handling periodic tasks than cyclic tasks within a specific time period.

Therefore, the best solution is to create a shell script (such as schedule.sh ), use the sleep command to control the execution interval in the script, and use the logic to determine the number of executions.

The schedule.sh script can be written like this: first calculate the total number of executions (from 21:30 to 22:30 for a total of 60 minutes, once every 8 minutes, about 8 times, rounding upward). Then use loop statements to sleep for 8 minutes after each task is executed. In order to ensure that the script stops after 22:30, time judgment is required to be added to the script.

Finally, set the schedule.sh script to execute once a day at 21:30 in crontab. The crontab setting is similar to: 30 21 * * * /path/to/schedule.sh ( /path/to/ needs to be replaced by the actual path of the script). crontab will execute schedule.sh once every day at 21:30, while the script is responsible for looping out tasks between 21:30 and 22:30.

This method combines the timing function of crontab and the process control capabilities of shell scripts, perfectly solving the problem of cycling tasks in a specific time period.

The above is the detailed content of How to use crontab to accurately control tasks to execute loops within a specified time period?. For more information, please follow other related articles on the PHP Chinese website!