I guess I can lot into CLI, do a DU for files_trashbin but would be good to see this in the Web UI.
To get back space I guess I could delete files older than a certain amount of time from files_trashbin?
Are there any file retention seting for this? I.e. time.
Unfortunately you can’t see the total size of the trashbin in the webui. You can cd into data/user and use
du -hsc files_trashbin to see the size of the trashbin like you already said. To completely clear the trashbin of a user, you can use
occ trashbin:cleanup username. you can also use this command without a user to clear all trashbins. If you only want to delete files that have a certain age, you can use
occ trashbin:expire username in the same fashion. this command uses the
trashbin_retention_obligation in your config.php, which by default should be set to 30 days. You can change the lifetime of files by changing this value, i will link you the right documentation so you can see how to set it to a specific value.
Config.php Parameters: Config.php Parameters :: ownCloud Documentation