Settings for my laptop to do nothing when I close the lid.
I use debian, without systemd.

In /etc/default/acpi-support (those two lines should be commented):

    #LID_SLEEP=true
    #LID_SHUTDOWN=true

In /etc/elogind/logind.conf (we explicitely set to 'ignore'):

    HandleLidSwitch=ignore
    HandleLidSwitchExternalPower=ignore