Php timed task

  question

Find php Timed Task Code
I hope the great gods can provide detailed codes.
Don’t know programming, but have ideas
Look at the train of thought first.
The overall idea is to use PHP timing to query custom keywords in the database (there are many)
If the query results in a custom keyword, replace it with a special character such as # (there is only one character)
At present, it is certain that the data submitted by users are stored in the following two tables
Articles and comments
Comments table structure
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Attached Figure articles Table Structure
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Can’t linux schedule tasks work? Or use supervise.