Preventing laptop wake up when opening the lid on linux

I found a way after googleing a bit smarter (it was difficult to find the correct search keys).

In short, the file /proc/acpi/wakeup has a line for LID which is enabled.

$ cat /proc/acpi/wakeup 
Device  S-state   Status   Sysfs node
PCIB      S4     disabled  pci:0000:00:1e.0
USB1      S3     disabled  pci:0000:00:1d.0
USB2      S3     disabled  pci:0000:00:1d.1
USB3      S3     disabled  pci:0000:00:1d.2
USB4      S3     disabled  pci:0000:00:1d.3
USB7      S3     disabled  pci:0000:00:1d.7
MODM      S3     disabled  
HDEF      S3     disabled  pci:0000:00:1b.0
PXS1      S4     disabled  pci:0000:02:00.0
LID       S4    *enabled   

If you echo " LID" > /proc/acpi/wakeup it will change to disable and the computer won't wake up on lid open.

Follow the instructions on the already mentioned link to set it permanent on your computer.