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[_] wordpress/cache(?) update weirdness

Chris Dawson chris at tallhat.com
Tue Nov 6 14:36:24 GMT 2018

> > an update (yes i'd worked through all of the 'obvious' stuff ;).
> > it does appear to be related to server cache. we requested a new root
> > password via the digital ocean control panel, which reboots the
> > droplet. this actually fixed the cache/update issue!
>
> That’s very odd - can’t think of any kind of cache that behaves like you described. MySQL query caches are expunged if the data updates, filesystem caches would be irrelevant, and by default web servers don’t cache at all. So unless they’ve snuck in a special invisible wordpress cache plugin (perhaps in mu-plugins?) no idea where it could be happening.
>
> If they’ve said “use the terminal” what are they actually telling you to do in the terminal? And is “server cache” explained anywhere (the term by itself is meaningless)?

it is all very odd. and taking me lots of time. caveat - i'm no server
admin, so am feeling my way here! apologies for terminology and
general stupidity on my part. from reading around, i think it's
either: Varnish, nginx reverse proxy cache (?) , or memcache.

DO aren't the quickest on tickets, and the help system is confusing.
i'm out of my depth when it comes to command line stuff.
all i know is that the droplet reboot sorted the issue, but i'd rather
have a simpler way to purge any/all server caches, and for DO to be
clear about what cache mechanisms are in place. (i didn't set up the
server/droplet btw, and the client has asked me not to contact the
person who did! sigh...)

ah, via the filesystem, there's a var/cache folder, containing

/var/cache/apt,,1541494840000
/var/cache/ldconfig,,1541432945000
/var/cache/man,,1541432944000
/var/cache/debconf,,1541432944000
/var/cache/pollinate,,1499684146000
/var/cache/dictionaries-common,,1499209382000
/var/cache/apache2,,1499209290000
/var/cache/apparmor,,1489626654000

any clues there?