1 修改文件的用户和用户组
chgrp： change group的简写，修改文件所属的用户组。
chown ：change owner的简写， 修改文件的所有者。
chown root:root aa.txt
2 网络代理的设置
公司网络，台式机，浏览器可以访问github,但是命令行不可以；开启电脑wifi后，浏览器不可以，命令行可以了。
有没有两种都可以的呢，可以通过设置git，不用ssh，而是https下载代码，如下
$ export HTTP_PROXY=http://ip:port $ export HTTPS_PROXY=http://ip:port $ gedit ~/.bashrc $ git clone https://github.com/project.git
3 after install ubuntu, need sudo apt-get update, get update from /etc/apt/sources.list
need set this :
/etc/apt/apt.conf Acquire::http::Proxy "http://proxy:prot";
then , success update.
4 安装搜狗输入法
从官网下载 deb,安装之后：
im-config
Click through and select fcitx. Click through.
Restart your computer. Click the keyboard in the top right corner. Press Configure Current Input Method. Press + to add a new language. De-select “Only show current language”. Type in sogou. Press OK. To switch between keyboards press Ctrl+Space
5 查找 某个目录下某种类型的文件中内容包含
find /xxx -name "*" | xargs grep "某内容"
6 通过android stuido下载 emulator update时，总是失败。报出error：
Not enough space on /tmp
解决方案：tmp所提供的空间可能不够系统使用，需要增大空间。
To do 1: open a terminal and run sudo umount -l /tmp sudo mount -t tmpfs -o size=1048576,mode=1777 overflow /tmp This should give you an 1MB partition (just like the one you had =P). Now, to increase the size, you increase the size in that line, so that, with size=10485760, you'd get 10 MB. Your goal is to find a number that is enough for the job, but leaves enough ram too
related link: https://askubuntu.com/questions/199565/not-enough-space-on-tmp
