On (Synology 415) NAS share :
BORG_REPO=ssh://user@syn415.local:22/~/borg_backup && borg init --encryption=keyfile $BORG_REPO
BORG_REPO="/path/to/backup" borg list
backup_name is the first column from list above
BORG_REPO="/path/to/backup::backup_name" && mkdir /tmp/borg && borg mount $BORG_REPO /tmp/borg
Unmount with:
borg umount /tmp/borg