Ubuntu runlebel

Ubuntu 16.04 uses systemd instead of init and hence the concept of runlevels is replaced by the term targets. So there is indeed a mapping between init-based runlevels and systemd-based targets:

   Mapping between runlevels and systemd targets
   ┌─────────┬───────────────────┐
   │Runlevel │ Target            │
   ├─────────┼───────────────────┤
   │0        │ poweroff.target   │
   ├─────────┼───────────────────┤
   │1        │ rescue.target     │
   ├─────────┼───────────────────┤
   │2, 3, 4  │ multi-user.target │
   ├─────────┼───────────────────┤
   │5        │ graphical.target  │
   ├─────────┼───────────────────┤
   │6        │ reboot.target     │
   └─────────┴───────────────────┘

Now, to just change the “runlevels” in 16.04, you can use for eg:

sudo systemctl isolate multi-user.target

To make this the default “runlevel”, you can use:

sudo systemctl enable multi-user.target
sudo systemctl set-default multi-user.target