The locate command sounds intuitive. I would expect it to locate files on the filesystem. However, it rarely finds files on the system that are indeed present:
$ locate ipsec.secrets
This gives no results, even when run from filesystem root directory /. The file is indeed present:
$ whereis ipsec.secrets ipsec: /usr/sbin/ipsec /etc/ipsec.secrets /etc/ipsec.d /etc/ipsec.conf /usr/lib/ipsec /usr/share/man/man8/ipsec.8.gz
Why was locate unable to find this file?
updatedbonly runs once a day, you need to run it with root privileges to find recent files.