汇总一些ubuntu相关的问题
1.Ubuntu支持安装多媒体播放插件（新系统安装后必备）
ubuntu-restricted-extras package allows users to install ability to play popular non-free media formats, including DVD, MP3, Quicktime, and Windows Media formats.
sudo apt-get install ubuntu-restricted-extras
2.VirtualBox is not currently allowed to access USB devices. You can change this by adding your user to the 'vboxusers' group. Please see the user manual for a more detailed explanation.
sudo usermod -aG vboxusers username
username为你登录系统的名称，添加之后，需要重启才能生效。