We may edit the configure file "/etc/systemd/logind.conf" and change one line from
#HandleLidSwitch=suspend
to
HandleLidSwitch=ignore
And then restart the service.
Restart the systemd daemon with this command:
sudo restart systemd-logind
or, from 15.04 onwards:
sudo service systemd-logind restart
We can also use command:
sudo service systemd-logind status
To check current status.
See: How can I tell Ubuntu to do nothing when I close my laptop lid? - Ask Ubuntu
