CRON AND CRONTAB IN-DEPTH: making sense of 30 4 1, 15 5

摘要

One of the most essential, and misunderstood, UNIX admin skills is being able to effectively use the cron daemon by maintaining your crontab files. The big problem is that the format of the crontab files can be very hard to grasp at first. Full of bizarre looking statements such as "30 4 1,15 5", the crontab scheduling statements can put off many users before they begin. By the end of this article it is my hope that you will not only have a firm grasp of the crontab format but also have some good ideas of what you can do with cron.