1.1 Go安装

• Linux
• FreeBSD
• Mac OS
• Windows

1. 下载源码包：https://golang.google.cn/dl/go1.11.1.linux-amd64.tar.gz
2. 将下载的源码包解压至 /usr/local目录： tar -C /usr/local -xzf go1.11.1.linux-amd64.tar.gz
3. 将 /usr/local/go/bin 目录添加至PATH环境变量： export PATH=$PATH:/usr/local/go/bin
4. 设置GOPATH，GOROOT环境变量： GOPATH是工作目录，GOROOT为Go的安装目录，这里为/usr/local/go/

注意：MAC系统下你可以使用 .pkg 结尾的安装包直接双击来完成安装，安装目录在 /usr/local/go/ 下。

GOPATH是我们的工作目录，可以有多个，用分号隔开。 GOROOT为Go的安装目录。

D:\goproject\src>go
Go is a tool for managing Go source code.
Usage:
        go <command> [arguments]
The commands are:
        bug         start a bug report
        build       compile packages and dependencies
        clean       remove object files and cached files
        doc         show documentation for package or symbol
        env         print Go environment information
        fix         update packages to use new APIs
        fmt         gofmt (reformat) package sources
        generate    generate Go files by processing source
        get         download and install packages and dependencies
        install     compile and install packages and dependencies
        list        list packages or modules
        mod         module maintenance
        run         compile and run Go program
        test        test packages
        tool        run specified go tool
        version     print Go version
        vet         report likely mistakes in packages
Use "go help <command>" for more information about a command.
Additional help topics:
        buildmode   build modes
        c           calling between Go and C
        cache       build and test caching
        environment environment variables
        filetype    file types
        go.mod      the go.mod file
        gopath      GOPATH environment variable
        gopath-get  legacy GOPATH go get
        goproxy     module proxy protocol
        importpath  import path syntax
        modules     modules, module versions, and more
        module-get  module-aware go get
        packages    package lists and patterns
        testflag    testing flags
        testfunc    testing functions
Use "go help <topic>" for more information about that topic.

• src存放源代码(比如：.go .c .h .s等) 按照Go 默认约定，go run，go install等命令的当前工作路径（即在此路径下执行上述命令）。
• pkg编译时生成的中间文件（比如：.a）
• bin编译后生成的可执行文件，接下来就可以试试代码编译运行了。

package main
import "fmt"
func main() {
   fmt.Println("Hello, World!")
}

D:\goproject>go run test.go
Hello，World!