Commit e07f089c authored by Andrew Gerrand's avatar Andrew Gerrand

doc: update install.html for binary distros, add install-source.html

R=bsiegert, rsc, r
CC=golang-dev
https://golang.org/cl/5605047
parent 8c4fecdc
<!--{
"Title": "Setting up and using gccgo"
"Title": "Setting up and using gccgo",
"Path": "/install/gccgo/"
}-->
<p>
......
<!--{
"Title": "Installing Go from source",
"Path": "/install/source/"
}-->
<h2 id="introduction">Introduction</h2>
<p>Go is an open source project, distributed under a
<a href="/LICENSE">BSD-style license</a>.
This document explains how to check out the sources,
build them on your own machine, and run them.
</p>
<div class="detail">
<p>
There are two official Go compiler tool chains.
This document focuses on the <code>gc</code> Go
compiler and tools (<code>6g</code>, <code>8g</code> etc.).
For information on how to use <code>gccgo</code>, a more traditional
compiler using the GCC back end, see
<a href="gccgo_install.html">Setting up and using gccgo</a>.
</p>
<p>
The Go compilers support three instruction sets.
There are important differences in the quality of the compilers for the different
architectures.
</p>
<dl>
<dt>
<code>amd64</code> (a.k.a. <code>x86-64</code>); <code>6g,6l,6c,6a</code>
</dt>
<dd>
The most mature implementation. The compiler has an effective
optimizer (registerizer) and generates good code (although
<code>gccgo</code> can do noticeably better sometimes).
</dd>
<dt>
<code>386</code> (a.k.a. <code>x86</code> or <code>x86-32</code>); <code>8g,8l,8c,8a</code>
</dt>
<dd>
Comparable to the <code>amd64</code> port.
</dd>
<dt>
<code>arm</code> (a.k.a. <code>ARM</code>); <code>5g,5l,5c,5a</code>
</dt>
<dd>
Supports only Linux binaries. Less tested than the other ports.
</dd>
</dl>
<p>
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.
</p>
<p>
The compilers can target the FreeBSD, Linux, NetBSD, OpenBSD, OS X (Darwin),
and Windows operating systems.
The full set of supported combinations is listed in the discussion of
<a href="#environment">environment variables</a> below.
</p>
</div>
<h2 id="ctools">Install C tools, if needed</h2>
<p>
The Go tool chain is written in C.
To build it, you need a C compiler installed.
</p>
<p>
On OS X, a C compiler can be installed as part of
<a href="http://developer.apple.com/Xcode/">Xcode</a>.
</p>
<p>
On Ubuntu/Debian, use <code>sudo apt-get install gcc libc6-dev</code>.
If you want to build 32-bit binaries on a 64-bit system you'll also need the
<code>libc6-dev-i386</code> package.
</p>
<p>
<font color="red">TODO: add Windows compiler info</font>
</p>
<h2 id="mercurial">Install Mercurial, if needed</h2>
<p>
To perform the next step you must have Mercurial installed. (Check that you
have an <code>hg</code> command.) This suffices to install Mercurial on most
systems:
</p>
<pre>
sudo easy_install mercurial==2.0
</pre>
<p>
On Ubuntu/Debian,
the Mercurial in your distribution's
package repository is most likely old and broken.
You might try this first:
</p>
<pre>apt-get install python-setuptools python-dev build-essential</pre>
<p>
If that fails, try installing manually from the
<a href="http://mercurial.selenic.com/wiki/Download">Mercurial Download</a>
page.</p>
</p>
<p>
Mercurial versions 1.7.x and up require the configuration of
<a href="http://mercurial.selenic.com/wiki/CACertificates">Certification Authorities</a>
(CAs). Error messages of the form:
</p>
<pre>
warning: code.google.com certificate with fingerprint b1:af: ... bc not verified (check hostfingerprints or web.cacerts config setting)
</pre>
<p>
when using Mercurial indicate that the CAs are missing.
Check your Mercurial version (<code>hg --version</code>) and
<a href="http://mercurial.selenic.com/wiki/CACertificates#Configuration_of_HTTPS_certificate_authorities">configure the CAs</a>
if necessary.
</p>
<h2 id="fetch">Fetch the repository</h2>
<p>
<p>Go will install to a directory named <code>go</code>.
Change to the directory that will be its parent
and make sure the <code>go</code> directory does not exist.
Then check out the repository:</p>
<pre>
$ hg clone -u release https://code.google.com/p/go
</pre>
<h2 id="install">Install Go</h2>
<p>
To build the Go distribution, run
</p>
<pre>
$ cd go/src
$ ./all.bash
</pre>
<p>
(To build under Windows use <code>all.bat</code>.)
</p>
<p>
If all goes well, it will finish by printing output like:
</p>
<pre>
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. ***
The compiler is 6g.
</pre>
<p>
where the details on the last few lines reflect the operating system,
architecture, and root directory used during the install.
</p>
<div class="detail">
<p>
For more information about ways to control the build, see the discussion of
<a href="#environment">environment variables</a> below.
</p>
</div>
<h2 id="testing">Testing your installation</h2>
<p>
Check that Go is installed correctly by building a simple program.
</p>
<p>
Create a file named <code>hello.go</code> and put the following program in it:
</p>
<pre>
package main
import "fmt"
func main() {
fmt.Printf("hello, world\n")
}
</pre>
<p>
Then run it with the <code>go</code> tool:
</p>
<pre>
$ go run hello.go
hello, world
</pre>
<p>
If you see the "hello, world" message then Go is installed correctly.
</p>
<h2 id="next">What's next</h2>
<p>
Start by taking <a href="http://code.google.com/p/go-tour/">A Tour of Go</a>
or reading the <a href="go_tutorial.html">Go Tutorial</a>.
</p>
<p>
For more detail about the process of building and testing Go programs
read <a href="/doc/code.html">How to Write Go Code</a>.
</p>
<p>
Build a web application by following the <a href="codelab/wiki/">Wiki
Codelab</a>.
</p>
<p>
Read <a href="effective_go.html">Effective Go</a> to learn about writing
idiomatic Go code.
</p>
<p>
For the full story, consult Go's extensive
<a href="docs.html">documentation</a>.
</p>
<h2 id="community">Community resources</h2>
<p>
For real-time help, there may be users or developers on
<code>#go-nuts</code> on the <a href="http://freenode.net/">Freenode</a> IRC server.
</p>
<p>
The official mailing list for discussion of the Go language is
<a href="http://groups.google.com/group/golang-nuts">Go Nuts</a>.
</p>
<p>
Bugs can be reported using the <a href="http://code.google.com/p/go/issues/list">Go issue tracker</a>.
</p>
<p>
For those who wish to keep up with development,
there is another mailing list, <a href="http://groups.google.com/group/golang-checkins">golang-checkins</a>,
that receives a message summarizing each checkin to the Go repository.
</p>
<h2 id="releases">Keeping up with releases</h2>
<p>
The Go project maintains two stable tags in its Mercurial repository:
<code>release</code> and <code>weekly</code>.
The <code>weekly</code> tag is updated about once a week, and should be used by
those who want to track the project's development.
The <code>release</code> tag is given, less often, to those weekly releases
that have proven themselves to be robust.
</p>
<p>
Most Go users will want to keep their Go installation at the latest
<code>release</code> tag.
New releases are announced on the
<a href="http://groups.google.com/group/golang-announce">golang-announce</a>
mailing list.
</p>
<p>
To update an existing tree to the latest release, you can run:
</p>
<pre>
$ cd go/src
$ hg pull
$ hg update release
$ ./all.bash
</pre>
<p>
To use the <code>weekly</code> tag run <code>hg update weekly</code> instead.
</p>
<h2 id="environment">Optional environment variables</h2>
<p>
The Go compilation environment can be customized by environment variables.
<i>None are required by the build</i>, but you may wish to set them
to override the defaults.
</p>
<dl>
<dt>
<code>$GOROOT</code>
</dt>
<dd>
<p>
The root of the Go tree, often <code>$HOME/go</code>.
This defaults to the parent of the directory where <code>all.bash</code> is run.
If you choose not to set <code>$GOROOT</code>, you must
run <code>gomake</code> instead of <code>make</code> or <code>gmake</code>
when developing Go programs using the conventional makefiles.
</dd>
<dt>
<code>$GOROOT_FINAL</code>
</dt>
<dd>
<p>
The value assumed by installed binaries and scripts when
<code>$GOROOT</code> is not set.
It defaults to the value used for <code>$GOROOT</code>.
If you want to build the Go tree in one location
but move it elsewhere after the build, set
<code>$GOROOT_FINAL</code> to the eventual location.
</dd>
<dt>
<code>$GOOS</code> and <code>$GOARCH</code>
</dt>
<dd>
<p>
The name of the target operating system and compilation architecture.
These default to the values of <code>$GOHOSTOS</code> and
<code>$GOHOSTARCH</code> respectively (described below).
<p>
Choices for <code>$GOOS</code> are
<code>darwin</code> (Mac OS X 10.5 and above), <code>freebsd</code>,
<code>linux</code>, <code>netbsd</code>, <code>openbsd</code>,
<code>plan9</code>, and <code>windows</code>.
Choices for <code>$GOARCH</code> are
<code>amd64</code> (64-bit x86, the most mature port),
<code>386</code> (32-bit x86), and <code>arm</code> (32-bit ARM).
The valid combinations of <code>$GOOS</code> and <code>$GOARCH</code> are:
<table cellpadding="0">
<tr>
<th width="50"><th align="left" width="100"><code>$GOOS</code></th> <th align="left" width="100"><code>$GOARCH</code></th> <th align="left"></th>
</tr>
<tr>
<td></td><td><code>darwin</code></td> <td><code>386</code></td>
</tr>
<tr>
<td></td><td><code>darwin</code></td> <td><code>amd64</code></td>
</tr>
<tr>
<td></td><td><code>freebsd</code></td> <td><code>386</code></td>
</tr>
<tr>
<td></td><td><code>freebsd</code></td> <td><code>amd64</code></td>
</tr>
<tr>
<td></td><td><code>linux</code></td> <td><code>386</code></td>
</tr>
<tr>
<td></td><td><code>linux</code></td> <td><code>amd64</code></td>
</tr>
<tr>
<td></td><td><code>linux</code></td> <td><code>arm</code></td>
</tr>
<tr>
<td></td><td><code>netbsd</code></td> <td><code>386</code></td>
</tr>
<tr>
<td></td><td><code>netbsd</code></td> <td><code>amd64</code></td>
</tr>
<tr>
<td></td><td><code>openbsd</code></td> <td><code>386</code></td>
</tr>
<tr>
<td></td><td><code>openbsd</code></td> <td><code>amd64</code></td>
</tr>
<tr>
<td></td><td><code>plan9</code></td> <td><code>386</code></td>
</tr>
<tr>
<td></td><td><code>windows</code></td> <td><code>386</code></td>
</tr>
<tr>
<td></td><td><code>windows</code></td> <td><code>amd64</code></td>
</tr>
</table>
<p>
</dd>
<dt>
<code>$GOHOSTOS</code> and <code>$GOHOSTARCH</code>
</dt>
<dd>
<p>
The name of the host operating system and compilation architecture.
These default to the local system's operating system and
architecture.
<p>
Valid choices are the same as for <code>$GOOS</code> and
<code>$GOARCH</code>, listed above.
The specified values must be compatible with the local system.
For example, you should not set <code>$GOHOSTARCH</code> to
<code>arm</code> on an x86 system.
</dd>
<dt>
<code>$GOBIN</code>
</dt>
<dd>
<p>
The location where binaries will be installed.
The default is <code>$GOROOT/bin</code>.
After installing, you will want to arrange to add this
directory to your <code>$PATH</code>, so you can use the tools.
</dd>
<dt>
<code>$GOARM</code> (arm, default=6)
</dt>
<dd>
<p>
The ARM architecture version the run-time libraries should target.
Setting <code>$GOARM</code> to 5 causes the linker to emit calls
to a software floating point implementation instead of using
hardware floating point support.
</dd>
</dl>
<p>
Note that <code>$GOARCH</code> and <code>$GOOS</code> identify the
<em>target</em> environment, not the environment you are running on.
In effect, you are always cross-compiling.
By architecture, we mean the kind of binaries
that the target environment can run:
an x86-64 system running a 32-bit-only operating system
must set <code>GOARCH</code> to <code>386</code>,
not <code>amd64</code>.
</p>
<p>
If you choose to override the defaults,
set these variables in your shell profile (<code>$HOME/.bashrc</code>,
<code>$HOME/.profile</code>, or equivalent). The settings might look
something like this:
</p>
<pre>
export GOROOT=$HOME/go
export GOARCH=amd64
export GOOS=linux
</pre>
......@@ -5,220 +5,119 @@
<h2 id="introduction">Introduction</h2>
<p>Go is an open source project, distributed under a
<a href="/LICENSE">BSD-style license</a>.
This document explains how to check out the sources,
build them on your own machine, and run them.
<p>
Go is an open source project with a BSD-style license.
There are two official Go compiler toolchains: the <code>gc</code> Go compiler
and the <code>gccgo</code> compiler that is part of the GNU C Compiler (GCC).
</p>
<div class="detail">
<p>
There are two distinct ways to experiment with Go.
This document focuses on the <code>gc</code> Go
compiler and tools (<code>6g</code>, <code>8g</code> etc.).
For information on how to use <code>gccgo</code>, a more traditional
compiler using the GCC back end, see
<a href="gccgo_install.html">Setting up and using gccgo</a>.
The <code>gc</code> compiler is the more mature and well-tested of the two.
This page is about installing a binary distribution of the <code>gc</code>
compiler.
</p>
<p>
The Go compilers support three instruction sets.
There are important differences in the quality of the compilers for the different
architectures.
For information about installing the <code>gc</code> compiler from source, see
<a href="/install/source/">Installing Go from source</a>.
For information about installing <code>gccgo</code>, see
<a href="/install/gccgo/">Setting up and using gccgo</a>.
</p>
<dl>
<dt>
<code>amd64</code> (a.k.a. <code>x86-64</code>); <code>6g,6l,6c,6a</code>
</dt>
<dd>
The most mature implementation. The compiler has an effective optimizer
(registerizer) and generates good code (although <code>gccgo</code>
can do noticeably better sometimes).
</dd>
<dt>
<code>386</code> (a.k.a. <code>x86</code> or <code>x86-32</code>); <code>8g,8l,8c,8a</code>
</dt>
<dd>
Comparable to the <code>amd64</code> port.
</dd>
<dt>
<code>arm</code> (a.k.a. <code>ARM</code>); <code>5g,5l,5c,5a</code>
</dt>
<dd>
Incomplete.
It only supports Linux binaries, the optimizer is incomplete,
and floating point uses the VFP unit.
However, all tests pass.
Work on the optimizer is continuing.
Tested against a Nexus One.
</dd>
</dl>
<h2 id="download">Obtaining the Go tools</h2>
<p>
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
(a fancier one is in the works), efficient array and string slicing,
support for segmented stacks, and a strong goroutine implementation.
Visit the
<a href="http://code.google.com/p/go/downloads">Go project's downloads page</a>
and select the binary distribution that matches
your operating system and processor architecture.
</p>
<p>
The compilers can target the FreeBSD, Linux, OpenBSD
and OS X (a.k.a. Darwin) operating systems.
(A port to Microsoft Windows is in progress but incomplete. See the
<a href="http://code.google.com/p/go/wiki/WindowsPort">Windows Port</a>
page for details.)
The full set of supported combinations is listed in the discussion of
<a href="#environment">environment variables</a> below.
</p>
</div>
<h2 id="ctools">Install C tools, if needed</h2>
<p>The Go tool chain is written in C.
To build it, you need these programs installed:
<ul>
<li>GCC,
<li>the standard C libraries,
<li>the parser generator Bison,
<li>GNU <tt>make</tt> (version 3.81 or later),
and
<li><tt>awk</tt>.
</ul>
</p>
<p>On OS X, they can be
installed as part of
<a href="http://developer.apple.com/Xcode/">Xcode</a>.
Official binary distributions are available
for the FreeBSD, Linux, Mac OS X, and Windows operating systems
and the 32-bit (<code>386</code>) and 64-bit (<code>amd64</code>)
x86 processor architectures.
</p>
<p>On Ubuntu/Debian, use <code>sudo apt-get install bison gawk gcc libc6-dev
make</code>. If you want to build 32-bit binaries on a 64-bit system you'll
also need the <code>libc6-dev-i386</code> package.
<p>
If a binary distribution is not available for your
OS/arch combination you may want to try
<a href="/install/source/">installing from source</a> or
<a href="/install/gccgo/">installing gccgo instead of gc</a>.
</p>
<h2 id="mercurial">Install Mercurial, if needed</h2>
<h2 id="install">Installing the Go tools</h2>
<p>
To perform the next step you must have Mercurial installed. (Check that you have an <code>hg</code> command.) This suffices to install Mercurial on most systems:
</p>
<pre>
sudo easy_install mercurial==2.0
</pre>
(On Ubuntu/Debian, you might try <code>apt-get install python-setuptools
python-dev build-essential</code> first. The Mercurial in your distribution's
package repository will most likely be old and broken.)
</p>
<p>
If that fails, try installing manually from the <a href="http://mercurial.selenic.com/wiki/Download">Mercurial Download</a> page.</p>
The Go binary distributions assume they will be installed in
<code>/usr/local/go</code>, but it is possible to install them in a different
location. If you do this, you will need to set the <code>GOROOT</code>
environment variable to that directory when using the Go tools.
</p>
<p>
Mercurial versions 1.7.x and up require the configuration of
<a href="http://mercurial.selenic.com/wiki/CACertificates">Certification Authorities</a>
(CAs). Error messages of the form:
</p>
<pre>
warning: code.google.com certificate with fingerprint b1:af: ... bc not verified (check hostfingerprints or web.cacerts config setting)
</pre>
<p>
when using Mercurial indicate that the CAs are missing.
Check your Mercurial version (<code>hg --version</code>) and
<a href="http://mercurial.selenic.com/wiki/CACertificates#Configuration_of_HTTPS_certificate_authorities">configure the CAs</a>
if necessary.
For example, if you installed Go to your home directory you should add the
following commands to <code>$HOME/.profile</code>:
</p>
<h2 id="fetch">Fetch the repository</h2>
<p>
<p>Go will install to a directory named <code>go</code>.
Change to the directory that will be its parent
and make sure the <code>go</code> directory does not exist.
Then check out the repository:</p>
<pre>
$ hg clone -u release https://code.google.com/p/go
export GOROOT=$HOME/go
export PATH=$PATH:$GOROOT/bin
</pre>
<h2 id="install">Install Go</h2>
<h3 id="freebsd_linux">FreeBSD and Linux</h3>
<p>
To build the Go distribution, run
Extract the archive into <code>/usr/local</code>, creating a Go tree in
<code>/usr/local/go</code> (typically this must be run as root or through
<code>sudo</code>):
</p>
<pre>
$ cd go/src
$ ./all.bash
tar -C /usr/local go.release.go1.tar.gz
</pre>
<p>
If all goes well, it will finish by printing output like:
Add <code>/usr/local/go/bin</code> to the <code>PATH</code> environment
variable. You can do this by adding this line to your <code>/etc/profile</code>
(for a system-wide installation) or <code>$HOME/.profile</code>:
</p>
<pre>
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 $PATH. ***
The compiler is 6g.
export PATH=$PATH:/usr/local/go/bin
</pre>
<p>
where the details on the last few lines reflect the operating system,
architecture, and root directory used during the install.
</p>
<div class="detail">
<p>For more information about ways to control the build,
see the discussion of <a href="#environment">environment variables</a> below.</p>
</div>
<h2 id="writing">Writing programs</h2>
<h3 id="osx">Mac OS X</h3>
<p>
Given a file <code>file.go</code>, compile it using
Open the <code>.pkg</code> file and follow the prompts to install the Go tools.
The package installs the Go distribution to <code>/usr/local/go</code>.
</p>
<pre>
$ 6g file.go
</pre>
<p>
<code>6g</code> is the Go compiler for <code>amd64</code>; it will write the output
in <code>file.6</code>. The &lsquo;<code>6</code>&rsquo; identifies
files for the <code>amd64</code> architecture.
The identifier letters for <code>386</code> and <code>arm</code>
are &lsquo;<code>8</code>&rsquo; and &lsquo;<code>5</code>&rsquo;.
That is, if you were compiling for <code>386</code>, you would use
<code>8g</code> and the output would be named <code>file.8</code>.
The package should put the <code>/usr/local/go/bin</code> directory in your
<code>PATH</code> environment variable. You may need to restart any open
Terminal sessions for the change to take effect.
</p>
<h3 id="windows">Windows</h3>
<p>
To link the file, use
<font color="red">TODO: windows installation instructions.</font>
</p>
<pre>
$ 6l file.6
</pre>
<h2 id="testing">Testing your installation</h2>
<p>
and to run it
Check that Go is installed correctly by building a simple program, as follows.
</p>
<pre>
$ ./6.out
</pre>
<p>A complete example:
<p>
Create a file named <code>hello.go</code> and put the following program in it:
</p>
<pre>
$ cat &gt;hello.go &lt;&lt;EOF
package main
import "fmt"
......@@ -226,36 +125,20 @@ import "fmt"
func main() {
fmt.Printf("hello, world\n")
}
EOF
$ 6g hello.go
$ 6l hello.6
$ ./6.out
hello, world
$
</pre>
<p>
There is no need to list <code>hello.6</code>'s package dependencies
(in this case, package <code>fmt</code>) on the <code>6l</code>
command line.
The linker learns about them by reading <code>hello.6</code>.
Then run it with the <code>go</code> tool:
</p>
<div class="detail">
<pre>
$ go run hello.go
hello, world
</pre>
<p>
To build more complicated programs, you will probably
want to use a
<code>Makefile</code>.
There are examples in places like
<code>go/src/cmd/godoc/Makefile</code>
and <code>go/src/pkg/*/Makefile</code>.
The
<a href="contribute.html">document</a>
about contributing to the Go project
gives more detail about
the process of building and testing Go programs.
If you see the "hello, world" message then your Go installation is working.
</p>
</div>
<h2 id="next">What's next</h2>
......@@ -264,6 +147,11 @@ Start by taking <a href="http://code.google.com/p/go-tour/">A Tour of Go</a>
or reading the <a href="go_tutorial.html">Go Tutorial</a>.
</p>
<p>
For more detail about the process of building and testing Go programs
read <a href="/doc/code.html">How to Write Go Code</a>.
</p>
<p>
Build a web application by following the <a href="codelab/wiki/">Wiki
Codelab</a>.
......@@ -279,39 +167,6 @@ For the full story, consult Go's extensive
<a href="docs.html">documentation</a>.
</p>
<h2 id="releases">Keeping up with releases</h2>
<p>
The Go project maintains two stable tags in its Mercurial repository:
<code>release</code> and <code>weekly</code>.
The <code>weekly</code> tag is updated about once a week, and should be used by
those who want to track the project's development.
The <code>release</code> tag is given, less often, to those weekly releases
that have proven themselves to be robust.
</p>
<p>
Most Go users will want to keep their Go installation at the latest
<code>release</code> tag.
New releases are announced on the
<a href="http://groups.google.com/group/golang-announce">golang-announce</a>
mailing list.
</p>
<p>
To update an existing tree to the latest release, you can run:
</p>
<pre>
$ cd go/src
$ hg pull
$ hg update release
$ ./all.bash
</pre>
<p>
To use the <code>weekly</code> tag run <code>hg update weekly</code> instead.
</p>
<h2 id="community">Community resources</h2>
......@@ -326,158 +181,6 @@ The official mailing list for discussion of the Go language is
</p>
<p>
Bugs can be reported using the <a href="http://code.google.com/p/go/issues/list">Go issue tracker</a>.
</p>
<p>
For those who wish to keep up with development,
there is another mailing list, <a href="http://groups.google.com/group/golang-checkins">golang-checkins</a>,
that receives a message summarizing each checkin to the Go repository.
</p>
<h2 id="environment">Optional environment variables</h2>
<p>
The Go compilation environment can be customized by environment variables.
<i>None are required by the build</i>, but you may wish to set them
to override the defaults.
Bugs should be reported using the
<a href="http://code.google.com/p/go/issues/list">Go issue tracker</a>.
</p>
<dl>
<dt>
<code>$GOROOT</code>
</dt>
<dd>
The root of the Go tree, often <code>$HOME/go</code>.
This defaults to the parent of the directory where <code>all.bash</code> is run.
If you choose not to set <code>$GOROOT</code>, you must
run <code>go tool make</code> instead of <code>make</code> or <code>gmake</code>
when developing Go programs using the conventional makefiles.
</dd>
<dt>
<code>$GOROOT_FINAL</code>
</dt>
<dd>
The value assumed by installed binaries and scripts when
<code>$GOROOT</code> is not set.
It defaults to the value used for <code>$GOROOT</code>.
If you want to build the Go tree in one location
but move it elsewhere after the build, set
<code>$GOROOT_FINAL</code> to the eventual location.
</dd>
<dt>
<code>$GOOS</code> and <code>$GOARCH</code>
</dt>
<dd>
The name of the target operating system and compilation architecture.
These default to the values of <code>$GOHOSTOS</code> and
<code>$GOHOSTARCH</code> respectively (described below).
<p>
Choices for <code>$GOOS</code> are
<code>darwin</code> (Mac OS X 10.5 or 10.6),
<code>freebsd</code>, <code>linux</code>, <code>openbsd</code>,
and <code>windows</code> (Windows, an incomplete port).
Choices for <code>$GOARCH</code> are <code>amd64</code> (64-bit x86, the most mature port),
<code>386</code> (32-bit x86), and
<code>arm</code> (32-bit ARM, an incomplete port).
The valid combinations of <code>$GOOS</code> and <code>$GOARCH</code> are:
<table cellpadding="0">
<tr>
<th width="50"><th align="left" width="100"><code>$GOOS</code></th> <th align="left" width="100"><code>$GOARCH</code></th> <th align="left"></th>
</tr>
<tr>
<td></td><td><code>darwin</code></td> <td><code>386</code></td>
</tr>
<tr>
<td></td><td><code>darwin</code></td> <td><code>amd64</code></td>
</tr>
<tr>
<td></td><td><code>freebsd</code></td> <td><code>386</code></td>
</tr>
<tr>
<td></td><td><code>freebsd</code></td> <td><code>amd64</code></td>
</tr>
<tr>
<td></td><td><code>linux</code></td> <td><code>386</code></td>
</tr>
<tr>
<td></td><td><code>linux</code></td> <td><code>amd64</code></td>
</tr>
<tr>
<td></td><td><code>linux</code></td> <td><code>arm</code></td> <td><i>incomplete</i></td>
</tr>
<tr>
<td></td><td><code>openbsd</code></td> <td><code>386</code></td>
</tr>
<tr>
<td></td><td><code>openbsd</code></td> <td><code>amd64</code></td>
</tr>
<tr>
<td></td><td><code>windows</code></td> <td><code>386</code></td> <td><i>incomplete</i></td>
</tr>
</table>
</dd>
<dt>
<code>$GOHOSTOS</code> and <code>$GOHOSTARCH</code>
</dt>
<dd>
The name of the host operating system and compilation architecture.
These default to the local system's operating system and
architecture.
<p>
Valid choices are the same as for <code>$GOOS</code> and
<code>$GOARCH</code>, listed above.
The specified values must be compatible with the local system.
For example, you should not set <code>$GOHOSTARCH</code> to
<code>arm</code> on an x86 system.
</dd>
<dt>
<code>$GOBIN</code>
</dt>
<dd>
The location where binaries will be installed.
The default is <code>$GOROOT/bin</code>.
After installing, you will want to arrange to add this
directory to your <code>$PATH</code>, so you can use the tools.
</dd>
<dt>
<code>$GOARM</code> (arm, default=6)
</dt>
<dd>
The ARM architecture version the run-time libraries should target.
Setting <code>$GOARM</code> to 5 causes the linker to emit calls
to a software floating point implementation instead of using
hardware floating point support.
</dd>
</dl>
<p>
Note that <code>$GOARCH</code> and <code>$GOOS</code> identify the
<em>target</em> environment, not the environment you are running on.
In effect, you are always cross-compiling.
By architecture, we mean the kind of binaries
that the target environment can run:
an x86-64 system running a 32-bit-only operating system
must set <code>GOARCH</code> to <code>386</code>,
not <code>amd64</code>.
</p>
<p>
If you choose to override the defaults,
set these variables in your shell profile (<code>$HOME/.bashrc</code>,
<code>$HOME/.profile</code>, or equivalent). The settings might look
something like this:
</p>
<pre>
export GOROOT=$HOME/go
export GOARCH=amd64
export GOOS=linux
</pre>
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