Well, if I edit it in the browser, I see the file with the correct changes in the server. If I edit it in the server, I see the correct changes in the browser. Still no luck with the cron job.
* * * * * cp -pf /home/-snip-/savedwiki/data/pages/playground/playground.txt /home/-snip-/public_html/wiki/data/pages/playground/
Directory name snipped for privacy, but it's pretty must exactly what's in the guide for setting this up, just with the correct file path. Also, I currently have it set to run every minute while I am testing (though I tried it with 5 minutes too just in case, and that is also not working). And I know it has to be the correct file paths, because whenever I edit the default file (the one in the savedwiki directory) on the server's side, the cron job will work exactly once, and then it will stop working.
I'll readily admit, this is my first time ever messing with cron jobs. But I'd hoped that, between carefully looking over the example on dokuwiki, and asking a friend to help explain what the different bits of this command actually mean, that I might be able to get it working. As I understand this, it is attempting to copy the file playground.txt from /home/-snip-/savedwiki/data/pages/playground/ to /home/-snip-/public_html/wiki/data/pages/playground/, and the -f means it will forcibly overwrite whatever is in the target directory. I suppose I don't exactly understand the -p part, something about the attributes of the original file being inherited? But this is what was in the example command on dokuwiki, so I figured it was probably correct to have it.
Although, you said that the renderer cache depends on the last modified time...... and the modified time doesn't seem to change when the cron job is running. Does the -p mean that the last modified time is not updating, and therefore it's not displaying the new page?
Testing with just -f instead of -pf, it seems that my playground is now properly resetting. But I do want to make sure that I'm not messing something up by removing the -p. Is that what the issue was? And if so, should the command on dokuwiki's guide be updated?