Turn Primary Display On/Off using xrandr
Run the xrandr command to identify your primary display:
% xrandr
Screen 0: minimum 320 x 200, current 1920 x 1080, maximum 8192 x 8192
eDP1 connected (normal left inverted right x axis y axis)
1920x1080 60.02 +
1400x1050 59.98
1280x1024 60.02
1280x960 60.00
1024x768 60.00
800x600 60.32 56.25
640x480 59.94
DP1 disconnected (normal left inverted right x axis y axis)
HDMI1 disconnected (normal left inverted right x axis y axis)
DP2 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 518mm x 324mm
1920x1200 59.95 +
1920x1080 59.93*
1600x1200 60.00
1680x1050 59.95
1280x1024 75.02 60.02
1440x900 59.89
1280x800 59.81
1024x768 75.03 70.07 60.00
800x600 72.19 75.00 60.32
640x480 75.00 72.81 66.67 59.94
720x400 70.08
HDMI2 disconnected (normal left inverted right x axis y axis)
In this example, eDP1 is the primary laptop display. To turn it off via the command line, run:
% xrandr --output eDP1 --off
To turn it back on again, run:
% xrandr --output eDP1 --auto