安装完 Go 后，可以在命令行中使用 go 命令。
使用 go --help 获取帮助：
$ go --help
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
....
获取 build 子命令的帮助：
$ go help build
获取版本号：
$ go version