I've encountered a problem with my mysql-server 5.7.17 installation on Ubuntu 16.04.
In my installation process I run
mysqld --initialize to initialize data directory for mysql :
mysqld --initialize-insecure --user=mysql --datadir=/blablabla
But this command seems to also delete a system user :
debian-sys-maint, which is used by OS when upgrading MySQL packages and some other stuff like this.
Why does this happen? The mysqld command apparently doesn't know that this user is "useful" for the system...
How I can correct this problem (prevent it from happening rather than recreating the user manually)?