As of go 1.2, a valid GOPATH is required to use the `go get` command:
https://golang.org/doc/code.html#GOPATH
You may wish to add the GOROOT-based install location to your PATH:
export PATH=$PATH:/usr/local/opt/go/libexec/bin
==> Summary
/usr/local/Cellar/go/1.5.1: 5330 files, 273M
------------
ogon:~ ym$ export PATH=$PATH:/usr/local/Cellar/go/1.5.1/libexec/bin/
bogon:~ ym$ export GOROOT=/usr/local/Cellar/go/1.5.1/
（/usr/local/Cellar/go/1.5.1/就是go的安装目录）
(GOPATH的路径不能设得跟GOROOT的路径一样。以后可临时设置GOPATH的环境变量，比如
mkdir gospace
cd gospace
export GOPATH=/path/to/gospace/
然后，就可在gospace目录里运行go get github.com/xx/yy了。）
－－－－－－－－－－
mac下，安装go环境，也可参考http://briteming.blogspot.com/2015/10/macgo.html
------------
ogon:~ ym$ export PATH=$PATH:/usr/local/Cellar/go/1.5.1/libexec/bin/
bogon:~ ym$ export GOROOT=/usr/local/Cellar/go/1.5.1/
（/usr/local/Cellar/go/1.5.1/就是go的安装目录）
(GOPATH的路径不能设得跟GOROOT的路径一样。以后可临时设置GOPATH的环境变量，比如
mkdir gospace
cd gospace
export GOPATH=/path/to/gospace/
然后，就可在gospace目录里运行go get github.com/xx/yy了。）
－－－－－－－－－－
mac下，安装go环境，也可参考http://briteming.blogspot.com/2015/10/macgo.html