在ubuntu14.04虚拟机上修改自定义大小的桌面屏幕分辨率，使用的命令：cvt，xrandr
0、首先查看下当前已经提供的分辨率设置：xrandr -q
[email protected]:/home/xxx/Desktop# xrandr -q
Screen 0: minimum 1 x 1, current 1504 x 768, maximum 8192 x 8192
Virtual1 connected primary 1504x768+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
800x600 60.0 + 60.3
2560x1600 60.0
1920x1440 60.0
1856x1392 60.0
1792x1344 60.0
1920x1200 59.9
1600x1200 60.0
1680x1050 60.0
1400x1050 60.0
1280x1024 60.0
1440x900 59.9
1280x960 60.0
1360x768 60.0
1280x800 59.8
1152x864 75.0
1280x768 59.9
1024x768 60.0
640x480 59.9
1504x768_60.00 59.9*
Virtual2 disconnected (normal left inverted right x axis y axis)
Virtual3 disconnected (normal left inverted right x axis y axis)
Virtual4 disconnected (normal left inverted right x axis y axis)
Virtual5 disconnected (normal left inverted right x axis y axis)
Virtual6 disconnected (normal left inverted right x axis y axis)
Virtual7 disconnected (normal left inverted right x axis y axis)
Virtual8 disconnected (normal left inverted right x axis y axis)
红色部分是我标明的，Virtual1 设备名称，后面会用到，maximum 8192 x 8192最大支持分辨率；
1、在终端输入：cvt 1920 1080，显示如下：
[email protected]:/home/xxx/Desktop# cvt 1920 1080
# 1920x1080 59.96 Hz (CVT 2.07M9) hsync: 67.16 kHz; pclk: 173.00 MHz
Modeline "1920x1080_60.00" 173.00 1920 2048 2248 2576 1080 1083 1088 1120 -hsync +vsync
红色部分会在--newmode命令中用到，直接复制即可。
2、接下来通过--newmode、--addmode、--output命令即可完成,如下：
[email protected]:/home/xxx/Desktop# xrandr --newmode "1920x1080_60.00" 173.00 1920 2048 2248 2576 1080 1083 1088 1120 -hsync +vsync
[email protected]:/home/xxx/Desktop# xrandr --addmode Virtual1 "1920x1080_60.00"
[email protected]:/home/xxx/Desktop# xrandr --output Virtual1 --mode "1920x1080_60.00"
此时，屏幕分辨率已经改变了。