Installing-Go-from-source
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Reference: Installing Go from source
Installing Go from source
- Introduction
- Install Go compiler binaries
- Install Git, if needed
- Fetch the repository
- (Optional) Switch to the master branch
- Install Go
- Testing your installation
- Set up your work environment
- Install additional tools
- Community resources
- Keeping up with releases
- Optional environment variables
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 is two official Go compiler tools chains. This document focused 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 compiler support five instrution sets. There are important differences in the quality of the compilers for the different architectures.
amd64 (also known as x86-64)
- amd64 (also known as x86-64) A mature implementation. The compiler has an effective optimizer (registerizer) and generates good code (although gccgo can do noticeably better sometimes).
- 386 (x86 or x86-32) Comparable to the amd64 port.
- arm (ARM) Supports Linux, FreeBSD, NetBSD 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 excercised as other ports.
- ppc64, ppc64le (64-bit PowerPC big- and little-endian) Supports Linux binaries. New in 1.5 and not as well excercised 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 goroutings, such as stacks that grow and shrink on demand.
The compilers can target the DragonFly BSD, FreeBSD, Linux, NetBSD, OpenBSD, OS X (Darwin), Plan 9, Solaris and Windows operating systems. The full set of supported combinations is listed in the discussion of environment variables below.
Install Go compiler binaries
The Go tool chain 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 $HOME/go1.4. (This path may be overridden by setting the GOROOT_BOOTSTRAP environment variable.)
Build the tools with Go version 1.4 or a point release (1.4.1, 1.4.2 etc.). Go 1.4 binaries can be found at the downloads page.
Download the zip or tarball of Go 1.4 for your platform and extract it to $HOME/go1.4 (or your nominated GOROOT_BOOTSTRAP location).
If you want to install Go 1.5 on a system that not supported by Go 1.4 (such as linux/pcc64) you can either use bootstrap.bash on a system that can bootstrap GO 1.5 normally, or bootstrap with gccgo 5.
When run as (for example) $ GOOS=linux GOARCH=pcc64 ./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 fo the given target type and used as GOROOT_BOOTSTRAP to bootstrap a local build.
To use gccgo, 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.
Fetch the repository
Go will install to a directory named go. Change to the directory that will be its parent and make sure the go directory does not exist. Then clone the repository and check out the latest release tag:
$ git clone https://go.googlesource.com/go
$ cd go
$ git checkout go1.5.1
(Optional) Switch to the master branch
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 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 informaiton about ways to control the build, see the discussion of environment variables below.
all.bash (or all.bat) run 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 enviroment
You’re almost done. You just need to do a litte more setup.
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 all of them, run the go get command:
$ go get golang.org/x/tools/cmd/...
Or if you want to install a specific command (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.
Note: The go command will install the godoc binary to $GOROOT/bin (or $GOBIN) and the cover and vet binaries to $GOROOT/pkg/tool/$GOOS_$GOARCH. You can access the latter commands with “go tool cover” and “go tool vet”.
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-chekins, 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 release are announced on the golang-announce mailing list. Each announcement mentions the latest release tag, for instance, go1.5.1.
To update an existing tree to the latest release, you can run:
$ cd go/src
$ git fetch
$ git checkout
What *
Optional enviroment 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.
- $GOROOT
The root of the Go tree, often $HOME/go. Its values is built into the tree when it is compiled, and defaults to the parent of the directory when all.bash was run. There is no need to set this unless you want to switch between multiple local copies of the repository.
- $GOROOT_FINAL
The value assumed by installed binaries and scripts when $GOROOT is not set explicitly. It defaults to the value of $GOROOT. If you want to build the Go tree in one location but move it elsewhere after the build, set $GOROOT_FINAL to the eventual location.
- $GOOS and $GOARCH
The name fo the target operating system and compilation architecture. These default to the values of $GOHOSTOS and $GOHOSTARCH respectively (described below).
Choice for $GOOS are darwin (Mac OS X 10.7 and above and iOS), dragonfly, freebsd, linux, netbsd, openbsd, plan9, solaris and windows. Choices for $GOARCH are amd64 (640bit x86, the most mature port), *386 (32-bit x86), arm (32-bit ARM), arm64 (64-bit ARM), ppc64le (PowerPC 64-bit, little-endian), and ppc64 (PowerPC 64-bit, big-endian). The valid combinations of $GOOS and $GOARCH are:
$GOOS$GOARCHdarwin386darwinamd64darwinarmdarwinarm64dragonflyamd64freebsd386freebsdamd64freebsdarmlinux386linuxamd64linuxarmlinuxarm64linuxppc64linuxppc64lenetbsd386netbsdamd64netbsdarmopenbsd386openbsdamd64openbsdarmplan9386plan9amd64solarisamd64windows386windowsamd64
- $GOBIN
The location where Go binaries will be installed. The default is $GOROOT/bin. After installing, you will want to arrange to add this directory to your $PATH, so you can use the tools. If $GOBIN is set, the go command installs all commands there.
- $GO386 (for 386 only, default is auto-detected if built on either 386 or amd64, 387 otherwise)
This controls the code generated by gc to use either the 387 floating-point unit (set to 387) or SSE2 instructions (set to sse2) for floating point computations.
- GO386=387: use x87 for floating point operations; should support aull x86 chips (Pentium MMX or later).
- GO386=sse2: use SSE2 for floating operations; has better performance than 387, but only avaliable on Pentium 4/Opteron/Athlon 64 or later.
- $GOARM (for arm only; default is auto-detected if building on the target processor, 6 if not)
This sets the ARM floating point co-processor architecture version the run-time should target. If you are compiling on the target system, its values will be auto-detected.
- GOARM=5: use software floating point; when CPU doesn’t have VFP co-processor
- GOARM=6: use VFPv1 only; default if cross compiling; usually ARM11 or better cores (VFPv2 or better is also supported)
- GOArM=7: use VFPv3; usually Cortex-A cores If in doubt, leave this variable unset, and adjust it if required when you first run the Go executable. The GoARM page on the Go community wiki contains further details regarding Go’s ARM support.
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, $HOME/.profile, or equivalent). The settings might look something like this:
export GOROOT=$HOME/go
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.