Php. how to update cache, ask for help,

Php. how to update the cache, ask for help, and I don't want to write a scheduled task, because the update frequency of the file is small. if it is cleared regularly, it will inevitably lead to waste. How to precisely crack down on modified cache files. For help,

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You know when updating. you can update the cache file when updating.

You know when updating. you can update the cache file when updating.
Yes, I know, but this project is going to be launched. You cannot update the cache for each update. After all, it is handed over to the operations staff. I don't know if they have changed.

What is your cache?
Normal thinking is that the program has changed, and the update cache is automatically triggered.

What cache?