export GOPATH=$HOME/go

GOPATH是Go的一个系统变量，设置这个是为了指定Go的workspace.

Find more in below page.

https://github.com/golang/go/wiki/SettingGOPATH 

export PATH=$HOME/go/bin:$PATH

设置$HOME/go/bin到当前进程的系统运行目录.

Find more in below pages.

https://stackoverflow.com/questions/13795237/what-does-the-export-command-do

http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#export

学习Go碰到一些Linux命令(未完)