Gpsd is a daemon for Unix platforms compatible with a large number of GNSS receivers. Learn more about gpsd on the official website at http://www.catb.org/gpsd.
On Ubuntu gpsd can be installed via APT as follows: sudo apt-get install gpsd gpsd-clients.
Once gpsd is installed, it needs to be configured to listen the correct port. A simpler way to make gpsd listen the right port is just to restart the daemon with correct arguments:
killall -INT gpsd
On most GNU/Linux systems, instead of directly specifying the TTY device such as /dev/ttyACM0, it is possible to use the persistent symlinks defined in the dev filesystem in /dev/serial/by-id/. These symlinks allow the user to refer directly to the device using its vendor name, product name, and (optionally) unique ID, which is more convenient because unlike TTY numbers these parameters are persistent.
For example, /dev/ttyACM0 in the example above could be replaced with /dev/serial/by-id/usb-Zubax_Robotics_Zubax_GNSS_34FFD305435730343944224300000000-if00 (the unique ID of your specific Zubax GNSS will be different), or just /dev/serial/by-id/usb-Zubax_Robotics_Zubax_GNSS* to refer to any connected Zubax GNSS regardless of its unique ID.
$ ls -l /dev/serial/by-id/
lrwxrwxrwx 1 root root 13 Dec 14 15:50 usb-Zubax_Robotics_Zubax_GNSS_34FFD305435730343944224300000000-if00 -> ../../ttyACM0