方法一：
xrandr -q
可以查看当前使用设备和分辨率

Screen 0: minimum 320 x 200, current 1366 x 768, maximum 8192 x 8192
LVDS-1 connected primary 1366x768+0+0 (normal left inverted right x axis y axis) 309mm x 173mm
   1366x768      60.10*+
   1360x768      59.80    59.96  
   1280x720      60.00    59.99    59.86    59.74  
   1024x768      60.04    60.00  
   960x720       60.00  
   928x696       60.05  
   896x672       60.01  
   1024x576      59.95    59.96    59.90    59.82  
   960x600       59.93    60.00  
   960x540       59.96    59.99    59.63    59.82  
   800x600       60.00    60.32    56.25  
   840x525       60.01    59.88  
   864x486       59.92    59.57  
   800x512       60.17  
   700x525       59.98  
   800x450       59.95    59.82  
   640x512       60.02  
   720x450       59.89  
   700x450       59.96    59.88  
   640x480       60.00    59.94  
   720x405       59.51    58.99  
   684x384       59.88    59.85  
   680x384       59.80    59.96  
   640x400       59.88    59.98  
   576x432       60.06  
   640x360       59.86    59.83    59.84    59.32  
   512x384       60.00  
   512x288       60.00    59.92  
   480x270       59.63    59.82  
   400x300       60.32    56.34  
   432x243       59.92    59.57  
   320x240       60.05  
   360x202       59.51    59.13  
   320x180       59.84    59.32  
VGA-1 disconnected (normal left inverted right x axis y axis)
HDMI-1 disconnected (normal left inverted right x axis y axis)
DP-1 disconnected (normal left inverted right x axis y axis)

也可以使用命令
xrandr |grep " connected"|cut -f1 -d " "

通过--brightness选项来调节屏幕的亮度
屏幕的亮度参数是从0.1到1.0, 从暗到亮
xrandr --output LVDS-1 --brightness 0.8

方法二：
只对intel显卡有效（自己没测试）

xbacklight -set [porcentaje-brillo]
如果想调节屏幕亮度为80%，可以执行
xbacklight -set 80
也可以增加或减少百分比
xbacklight -inc 10 #增加10%
xbacklight -dec 10 %减少10%