Golang compilation env setup

GOROOT

The environment variable GOROOT indicates the Go language installation directory.

In windows, the default value of GOROOT is C:/go, while in macOS or Linux, the default value of GOROOT is usr/local/go. If you install Go in another directory, you need to change the value of GOROOT to the corresponding directory.

In addition, GOROOT/bin contains the toolchain that Go provides for us, so you should configure GOROOT/bin to the environment variable PATH so that we can use the Go toolchain globally.

Linux setup GOROOT demo

export GOROOT=~/go
export PATH=$PATH:$GOROOT/bin

GOPATH

Note that the value of GOPATH cannot be the same as GOROOT

The environment variable GOPATH is used to specify our development workspace, which is where the source code, test files, library static files, and executable files are stored.

The default value of GOPATH in Unix-like (Mac OS or Linux) operating systems is $home/go. And the default value of GOPATH in Windows is %USERPROFILE%\go (for example, in Admin user, its value is C:\Users\Admin\go).

Of course, we can change the workspace by modifying GOPATH, for example, by setting the work opt/go in the following way.

Linux setting GOPATH demo

export GOPATH=/opt/go

Also, you can set multiple workspaces in GOPATH, e.g.

export GOPATH=/opt/go;$home/go

subdirectory of GOPATH

The above code means that we specify two workspaces, but when we use the go get command to get the remote library, it will usually be installed in the first workspace.

According to the Go development specification, each work in the GOPATH directory is generally divided into three subdirectories: src, pkg, and bin, so we see each workspace like this.

So we see the workspace as follows.

bin/
    hello                          # command executable 可执行文件
    outyet                         # command executable 可执行文件
src/
    golang.org/x/example/
        .git/                      # Git repository metadata git仓库元数据
    hello/
        hello.go                         # command source 命令行代码
    outyet/
        main.go                          # command source 命令行代码
        main_test.go                     # test source      测试代码
    stringutil/
        reverse.go                       # package source 库文件
        reverse_test.go                  # test source      库文件
    golang.org/x/image/
        .git/                      # Git repository metadata git仓库元数据
    bmp/
        reader.go                        # package source 库文件
        writer.go                        # package source 库文件
    ... (many more repositories and packages omitted) ...

The src directory holds the source code files we developed, the corresponding directory below it is called packages, pkg holds the compiled library static files, and bin has the executable files in the backend of the source code compilation.

GOBIN

The environment variable GOBIN indicates the directory where the compiled binary commands of our development program are installed.

When we use the go install command to compile and package the application, the command will package the compiled binary program GOBIN directory. Generally, we set GOBIN to GOPATH/bin directory.

Linux GOBIN setup demo

export GOBIN=$GOPATH/bin

Cross-Compilation

What is cross-compilation? By cross-compiling, we can generate code on one platform that can run on another platform. For example, we can generate binary programs that run on a 64-bit Linux OS on a 32-bit Windows OS development environment.

Cross-compiling in other programming languages may require third-party tools, but cross-compiling in Go is very simple, and the simplest thing to do is to set the two environment variables GOOS and GOARCH.

GOOS and GOARCH

The default value of GOOS is our current operating system, and if windows, Linux, or mac os is operating, the value is darwin. GOARCH indicates the CPU architecture, such as 386, amd64, arm, etc.

Get the GOOS and GOARCH values

We can use the go env command to get the current GOOS and GOARCH values.

go env GOOS GOARCH

Range of GOOS and GOARCH values

GOOS and GOARCH values appear in pairs and can only be the values corresponding to the following list.

$GOOS	$GOARCH
android	arm
darwin	386
darwin	amd64
darwin	arm
darwin	arm64
dragonfly	amd64
freebsd	386
freebsd	amd64
freebsd	arm
linux	386
linux	amd64
linux	arm
linux	arm64
linux	ppc64
linux	ppc64le
linux	mips
linux	mipsle
linux	mips64
linux	mips64le
linux	s390x
netbsd	386
netbsd	amd64
netbsd	arm
openbsd	386
openbsd	amd64
openbsd	arm
plan9	386
plan9	amd64
solaris	amd64
windows	386
windows	amd64

Example

compiles a target program running on a 64-bit Linux operating system

GOOS=linux GOARCH=amd64 go build main.go

Compile target program on an arm architecture Android operation

GOOS=android GOARCH=arm GOARM=7 go build main.go

Environment variables list

Although we generally configure just a few environment variables, the Go language provides many environment variables that give us the freedom to customize development and compiler behavior.

Here is a list of all the environment variables provided by Go, which can generally be divided into the following categories, so it's good to know roughly because we can never use some environment variables.

via environment variables

GCCGO
GOARCH
GOBIN
GOCACHE
GOFLAGS
GOOS
GOPATH
GOPROXY
GORACE
GOROOT
GOTMPDIR

Environment variables to use with cgo

CC
CGO_ENABLED
CGO_CFLAGS
CGO_CFLAGS_ALLOW
CGO_CFLAGS_DISALLOW
CGO_CPPFLAGS, CGO_CPPFLAGS_ALLOW, CGO_CPPFLAGS_DISALLOW
CGO_CXXFLAGS, CGO_CXXFLAGS_ALLOW, CGO_CXXFLAGS_DISALLOW
CGO_FFLAGS, CGO_FFLAGS_ALLOW, CGO_FFLAGS_DISALLOW
CGO_LDFLAGS, CGO_LDFLAGS_ALLOW, CGO_LDFLAGS_DISALLOW
CXX
PKG_CONFIG
AR

Environment variables related to the system architecture system

GOARM
GO386
GOMIPS
GOMIPS64

Dedicated environment variables

GCCGOTOOLDIR
GOROOT_FINAL
GO_EXTLINK_ENABLED
GIT_ALLOW_PROTOCOL

Other environment variables

GOEXE
GOHOSTARCH
GOHOSTOS
GOMOD
GOTOOLDIR