I got a message "21 updates are security updates." when I login to my ubuntu server but I can't find the updates. How can I find it and update the security updates. I want to update only the security updates.
$ ssh MY_SERVER
Welcome to Ubuntu 16.04.3 LTS (GNU/Linux 4.4.0-141-generic x86_64)
204 packages can be updated.
21 updates are security updates.
New release '18.04.1 LTS' available.
Run 'do-release-upgrade' to upgrade to it.
$ sudo apt-get upgrade -s | grep -i security
// result is empty