Help to change sync option for calendar

HI all,

I found this post

but If I try to run the command within shell of my nextcloudpi i see this:

root@nextcloudpi:/var/www/nextcloud/config# sudo -u www-data php occ config:app:set da
v calendarSubscriptionRefreshRate --value “PT30M”
Could not open input file: occ

any hint?

“root@nextcloudpi:/var/www/nextcloud”
not
“root@nextcloudpi:/var/www/nextcloud/config”