How to put Nextcloud in maintenance mode and crate a Nextcloud backup?

Hi,
I’ve just installed umbrel server and installed nextcloud and photoprism. I’ve used nextcloud maintenance mode with a occ command but in umbrel server I don’t know how to run commands inside docker images. I want a guide about backing up my data on nextcloud which is installed on umbrel server.

I have the same problem. Trying to backup nextcloud db, config and web with no success, I guess I cannot identify a correct pathway in rsync -Aavx nextcloud/ nextcloud-dirbkp_date +"%Y%m%d"/, I can create the nextcloud-dirbkp_` being a root in the nexcloud_web_1 container but the data are not transferred - do I need to run this command from the root on this container

also when using mysqldump --single-transaction -h [server] -u [username] -p[password] [db_name] > nextcloud-sqlbkp_date +"%Y%m%d".bak with relevant serber/username and password /db_name I have problems, it can be run from nexcloud_db_1 container but does not allow me to use nextcloud-sqlbkp , have to save is as temp file - is it a normal behaviour