Introduction

Go is an open source project, distributed under a BSD-style license. This document explains how to check out the sources, build them on your own machine, and run them.

Most users don't need to do this, and will instead install from precompiled binary packages as described in Getting Started, a much simpler process. If you want to help develop what goes into those precompiled packages, though, read on.

There are two official Go compiler toolchains. This document focuses on the gc Go compiler and tools. For information on how to work on gccgo, a more traditional compiler using the GCC back end, see Setting up and using gccgo.

The Go compilers support eight instruction sets. There are important differences in the quality of the compilers for the different architectures.

amd64 (also known as x86-64)
A mature implementation.
386 (x86 or x86-32)
Comparable to the amd64 port.
arm (ARM)
Supports Linux, FreeBSD, NetBSD, OpenBSD and Darwin binaries. Less widely used than the other ports.
arm64 (AArch64)
Supports Linux and Darwin binaries. New in 1.5 and not as well exercised as other ports.
ppc64, ppc64le (64-bit PowerPC big- and little-endian)
Supports Linux binaries. New in 1.5 and not as well exercised as other ports.
mips, mipsle (32-bit MIPS big- and little-endian)
Supports Linux binaries. New in 1.8 and not as well exercised as other ports.
mips64, mips64le (64-bit MIPS big- and little-endian)
Supports Linux binaries. New in 1.6 and not as well exercised as other ports.
s390x (IBM System z)
Supports Linux binaries. New in 1.7 and not as well exercised as other ports.

Except for things like low-level operating system interface code, the run-time support is the same in all ports and includes a mark-and-sweep garbage collector, efficient array and string slicing, and support for efficient goroutines, such as stacks that grow and shrink on demand.

The compilers can target the DragonFly BSD, FreeBSD, Linux, NetBSD, OpenBSD, macOS (Darwin), Plan 9, Solaris and Windows operating systems. The full set of supported combinations is listed in the discussion of environment variables below.

See the main installation page for the overall system requirements. The following additional constraints apply to systems that can be built only from source:

Install Go compiler binaries

The Go toolchain is written in Go. To build it, you need a Go compiler installed. The scripts that do the initial build of the tools look for an existing Go tool chain in $GOROOT_BOOTSTRAP. If unset, the default value of GOROOT_BOOTSTRAP is $HOME/go1.4.

There are many options for the bootstrap toolchain. After obtaining one, set GOROOT_BOOTSTRAP to the directory containing the unpacked tree. For example, $GOROOT_BOOTSTRAP/bin/go should be the go command binary for the bootstrap toolchain.

To use a binary release as a bootstrap toolchain, see the downloads page or use any other packaged Go distribution.

To build a bootstrap toolchain from source, use either the git branch release-branch.go1.4 or go1.4-bootstrap-20171003.tar.gz, which contains the Go 1.4 source code plus accumulated fixes to keep the tools running on newer operating systems. (Go 1.4 was the last distribution in which the toolchain was written in C.) After unpacking the Go 1.4 source, cd to the src subdirectory, set CGO_ENABLED=0 in the environment, and run make.bash (or, on Windows, make.bat).

To cross-compile a bootstrap toolchain from source, which is necessary on systems Go 1.4 did not target (for example, linux/ppc64le), install Go on a different system and run bootstrap.bash.

When run as (for example) 

$ GOOS=linux GOARCH=ppc64 ./bootstrap.bash

bootstrap.bash cross-compiles a toolchain for that GOOS/GOARCH combination, leaving the resulting tree in ../../go-${GOOS}-${GOARCH}-bootstrap. That tree can be copied to a machine of the given target type and used as GOROOT_BOOTSTRAP to bootstrap a local build.

To use gccgo as the bootstrap toolchain, you need to arrange for $GOROOT_BOOTSTRAP/bin/go to be the go tool that comes as part of gccgo 5. For example on Ubuntu Vivid: 

$ sudo apt-get install gccgo-5
$ sudo update-alternatives --set go /usr/bin/go-5
$ GOROOT_BOOTSTRAP=/usr ./make.bash

Install Git, if needed

To perform the next step you must have Git installed. (Check that you have a git command before proceeding.)

If you do not have a working Git installation, follow the instructions on the Git downloads page.

(Optional) Install a C compiler

To build a Go installation with cgo support, which permits Go programs to import C libraries, a C compiler such as gcc or clang must be installed first. Do this using whatever installation method is standard on the system.

To build without cgo, set the environment variable CGO_ENABLED=0 before running all.bash or make.bash.

Fetch the repository

Change to the directory where you intend to install Go, and make sure the goroot directory does not exist. Then clone the repository and check out the latest release tag (go1.12, for example):

$ git clone https://go.googlesource.com/go goroot
$ cd goroot
$ git checkout <tag>

Where <tag> is the version string of the release.

Go will be installed in the directory where it is checked out. For example, if Go is checked out in $HOME/goroot, executables will be installed in $HOME/goroot/bin. The directory may have any name, but note that if Go is checked out in $HOME/go, it will conflict with the default location of $GOPATH. See GOPATH below.

If you intend to modify the go source code, and contribute your changes to the project, then move your repository off the release branch, and onto the master (development) branch. Otherwise, skip this step.

$ git checkout master

Install Go

To build the Go distribution, run 

$ cd src
$ ./all.bash

(To build under Windows use all.bat.)

If all goes well, it will finish by printing output like: 

ALL TESTS PASSED

---
Installed Go for linux/amd64 in /home/you/go.
Installed commands in /home/you/go/bin.
*** You need to add /home/you/go/bin to your $PATH. ***

where the details on the last few lines reflect the operating system, architecture, and root directory used during the install.

For more information about ways to control the build, see the discussion of environment variables below. all.bash (or all.bat) runs important tests for Go, which can take more time than simply building Go. If you do not want to run the test suite use make.bash (or make.bat) instead.

Testing your installation

Check that Go is installed correctly by building a simple program.

Create a file named hello.go and put the following program in it: 

package main

import "fmt"

func main() {
	fmt.Printf("hello, world\n")
}

Then run it with the go tool: 

$ go run hello.go
hello, world

If you see the "hello, world" message then Go is installed correctly.

Set up your work environment

You're almost done. You just need to do a little more setup.

How to Write Go Code Learn how to set up and use the Go tools

The How to Write Go Code document provides essential setup instructions for using the Go tools.

Install additional tools

The source code for several Go tools (including godoc) is kept in the go.tools repository. To install one of the tools (godoc in this case): 

$ go get golang.org/x/tools/cmd/godoc

To install these tools, the go get command requires that Git be installed locally.

You must also have a workspace (GOPATH) set up; see How to Write Go Code for the details.

Community resources

The usual community resources such as #go-nuts on the Freenode IRC server and the Go Nuts mailing list have active developers that can help you with problems with your installation or your development work. For those who wish to keep up to date, there is another mailing list, golang-checkins, that receives a message summarizing each checkin to the Go repository.

Bugs can be reported using the Go issue tracker.

Keeping up with releases

New releases are announced on the golang-announce mailing list. Each announcement mentions the latest release tag, for instance, go1.9.

To update an existing tree to the latest release, you can run: 

$ cd go/src
$ git fetch
$ git checkout <tag>
$ ./all.bash

Where <tag> is the version string of the release.

Optional environment variables

The Go compilation environment can be customized by environment variables. None is required by the build, but you may wish to set some to override the defaults.

Note that $GOARCH and $GOOS identify the target environment, not the environment you are running on. In effect, you are always cross-compiling. By architecture, we mean the kind of binaries that the target environment can run: an x86-64 system running a 32-bit-only operating system must set GOARCH to 386, not amd64.

If you choose to override the defaults, set these variables in your shell profile ($HOME/.bashrc, $HOME/.profile, or equivalent). The settings might look something like this: 

export GOARCH=amd64
export GOOS=linux

although, to reiterate, none of these variables needs to be set to build, install, and develop the Go tree.