Copy files from a Container to another

Create a directory on the host and add a mountpoint to that directory to both containers. Make sure to use the same user/group ID in both containers and allow read/write access for those user/group ID (+100000 when unprivileged) on the host.
 
I know I can `pct pull` and `pct push` from the Proxmox server itself but how can I directly copy files from one container to another?
There is also the `pct mount` command. I guess you need to take care of destination permissions regardless of the method you chose.
 
Create a directory on the host and add a mountpoint to that directory to both containers. Make sure to use the same user/group ID in both containers and allow read/write access for those user/group ID (+100000 when unprivileged) on the host.
I think it's overkill for copy some files now and then but for something more regular it's ok.
There is also the `pct mount` command. I guess you need to take care of destination permissions regardless of the method you chose.
So, I could also do:
Bash:
cp /rpool/data/subvol-100-disk-0/tmp/myfile.txt /rpool/data/subvol-300-disk-0/tmp/
and change destination permissions accordingly.