GOPATH和GOBIN在Fedora中设置并导出,但仍然未安装程序

我在Fedora 21笔记本电脑上安装了GO,我设置了GOPATH和GOBIN,但出于某种原因,它不允许我安装我的GO程序。

pred@computer01 [20:03:02] ~  
$ echo $GOPATH
/home/pred/Documents/GO
pred@computer01 [20:03:11] ~  
$ echo $GOBIN
/home/pred/Documents/GO/bin
pred@computer01 [20:03:15] ~  
$ cd $GOPATH
pred@computer01 [20:03:21] ~/Documents/GO  
$ go install src/github.com/pred3/go_helloworld/helloworld/helloworld.go 
go install: no install location for .go files listed on command line (GOBIN not set)
pred@computer01 [20:03:32] ~/Documents/GO  
$ go env
GOARCH="amd64"
GOBIN="/home/pred/Documents/GO/bin"
GOCHAR="6"
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/pred/Documents/GO"
GORACE=""
GOROOT="/usr/lib/golang"
GOTOOLDIR="/usr/lib/golang/pkg/tool/linux_amd64"
CC="gcc"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0"
CXX="g++"
CGO_ENABLED="1"

我还应该做些什么才能让它发挥作用?

--编辑--

如下所述发出以下命令也会出现错误。

pred@computer1 [21:22:51] ~/Documents/GO  
$ go install src/github.com/pred3/go_helloworld/helloworld
can't load package: package src/github.com/predatorian3/go_helloworld/helloworld: cannot find package "src/github.com/pred3/go_helloworld/helloworld" in any of:
    /usr/lib/golang/src/src/github.com/pred3/go_helloworld/helloworld (from $GOROOT)
    /home/pred/Documents/GO/src/src/github.com/pred3/go_helloworld/helloworld (from $GOPATH)

然而,我没有 package main 在我尝试安装的go文件的开头。一旦我把它改成 包装总管 它奏效了。我不知道为什么不能使用不同的包名。