xrandr

Set the size, orientation and/or reflection of the outputs for a screen. More information: https://www.x.org/releases/current/doc/man/man1/xrandr.1.xhtml.

• Display the current state of the system (known screens, resolutions, ...):
  xrandr --query
• Disable disconnected outputs and enable connected ones with default settings:
  xrandr --auto
• Change the resolution and update frequency of DisplayPort 1 to 1920x1080, 60Hz:
  xrandr --output {{DP1}} --mode {{1920x1080}} --rate {{60}}
• Set the resolution of HDMI2 to 1280x1024 and put it on the right of DP1:
  xrandr --output {{HDMI2}} --mode {{1280x1024}} --right-of {{DP1}}
• Disable the VGA1 output:
  xrandr --output {{VGA1}} --off
• Set the brightness for LVDS1 to 50%:
  xrandr --output {{LVDS1}} --brightness {{0.5}}