View your own image in this forum.
https://moodle.org/pluginfile.php/11602/user/icon/moodleorgcleaned_moodleorg/f1?rev=1295353
See the 'f1' ... that's the real file name me thinks .... in the meta data of the DB (every user has an 'f1' image ... but buried in the moodle file system somewhere the file is named via a content hash name and spread all over creation in filedir. :\
But, in looking at the URL to your own image above one might be able to create a looping script the checking user ID numbers .... assuming 11602 is your user id number on this system.
Did have a sys admin one time who found the url to his pic and was using that URL as an 'uptime checker' of his own making .... if that helps any.
'spirit of sharing', Ken