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264 lines
6.3 KiB
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264 lines
6.3 KiB
HTML
<!-- Installing Go -->
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<h2>Introduction</h2>
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<p>
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There are two distinct ways to experiment with Go.
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This document explains how to check out, build, and use the <code>gc</code> Go
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compiler and tools (<code>6g</code>, <code>8g</code> etc.).
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For information on how to use <code>gccgo</code>, a more traditional
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compiler using the GCC back end, see
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<a href="gccgo_install.html">Setting up and using gccgo</a>.
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</p>
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<h2>Environment variables</h2>
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<p>The Go compilation environment depends on three environment
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variables that you should set in your <code>.bashrc</code> or equivalent,
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plus one optional variable:</p>
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<dl>
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<dt>
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<code>$GOROOT</code>
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</dt>
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<dd>The root of the Go tree. Typically this is <code>$HOME/go</code>
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but it can be any directory.
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</dd>
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<dt>
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<code>$GOOS</code> and <code>$GOARCH</code>
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</dt>
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<dd>
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The name of the target operating system and compilation architecture.
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Choices for <code>$GOOS</code> are <code>linux</code>,
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<code>darwin</code> (Mac OS X 10.5 or 10.6),
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and <code>nacl</code> (Native Client, an incomplete port).
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Choices for <code>$GOARCH</code> are <code>amd64</code> (64-bit x86, the most mature port),
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<code>386</code> (32-bit x86), and
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<code>arm</code> (32-bit ARM, an incomplete port).
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The valid combinations are
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<code>linux</code>/<code>amd64</code>,
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<code>linux</code>/<code>arm</code>,
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<code>linux</code>/<code>386</code>,
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<code>darwin</code>/<code>amd64</code>,
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<code>darwin</code>/<code>386</code>,
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and
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<code>nacl</code>/<code>386</code>.
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</dd>
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<dt>
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<code>$GOBIN</code> (optional)
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</dt>
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<dd>
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The location where binaries will be installed.
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If you set <code>$GOBIN</code>, you need to ensure that it
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is in your <code>$PATH</code> so that newly built Go-specific
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command such as the compiler can be found during the build.
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The default, <code>$HOME/bin</code>, may already be in your <code>$PATH</code>.
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</dd>
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</dl>
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<p>
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Note that <code>$GOARCH</code> and <code>$GOOS</code> identify the
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<em>target</em> environment, not the environment you are running on.
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In effect, you are always cross-compiling.
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</p>
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<p>
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After setting these variables in your <code>.bashrc</code>, double-check them by
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listing your environment.
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</p>
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<pre>
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$ env | grep '^GO'
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</pre>
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<h2>Ports</h2>
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<p>
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Go compilers support two operating systems (Linux, Mac OS X) and
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three instruction sets.
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The versions for Linux and Mac are equally capable except that the ARM port
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does not run on OS X (yet).
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</p>
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<p>
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There are important differences in the quality of the compilers for the different
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architectures.
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</p>
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<dl>
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<dt>
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<code>amd64</code> (a.k.a. <code>x86-64</code>); <code>6g,6l,6c,6a</code>
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</dt>
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<dd>
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The most mature implementation. The compiler has an effective optimizer
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(registerizer) and generates good code (although <code>gccgo</code>
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can do noticeably better sometimes).
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</dd>
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<dt>
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<code>386</code> (a.k.a. <code>x86</code> or <code>x86-32</code>); <code>8g,8l,8c,8a</code>
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</dt>
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<dd>
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Comparable to the <code>amd64</code> port. Not as well soaked but
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should be nearly as solid.
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</dd>
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<dt>
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<code>arm</code> (a.k.a. <code>ARM</code>); <code>5g,5l,5c,5a</code>
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</dt>
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<dd>
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It's got a couple of outstanding bugs but is improving. Tested against QEMU
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and an android phone.
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</dd>
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</dl>
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<p>
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Except for things like low-level operating system interface code, the runtime
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support is the same in all ports and includes a mark-and-sweep garbage collector
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(a fancier one is in the works), efficient array and string slicing,
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support for segmented stacks, and a strong goroutine implementation.
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</p>
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<p>
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See the separate <a href="gccgo_install.html"><code>gccgo</code> document</a>
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for details about that compiler and environment.
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</p>
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<h2>Fetch the repository</h2>
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<p>
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If you do not have Mercurial installed (you do not have an <code>hg</code> command),
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this command:
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</p>
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<pre>
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$ sudo easy_install mercurial
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</pre>
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<p>works on most systems.
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If that fails, visit the <a href="http://mercurial.selenic.com/wiki/Download">Mercurial Download</a> page.</p>
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<p>Make sure the <code>$GOROOT</code> directory does not exist or is empty.
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Then check out the repository:</p>
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<!-- TODO(go-dev): Replace with http://go.googlecode.com/ for launch. -->
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<pre>
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$ hg clone http://r45/ $GOROOT
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</pre>
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<h2>Install Go</h2>
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<p>You need to have the parser generator Bison installed.
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It is installed as part of Xcode on OS X.
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If you need it on Linux,
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</p>
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<pre>
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$ sudo apt-get install bison
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</pre>
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<p>
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(or the equivalent on your Linux distribution).
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</p>
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<p>
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To build the Go distribution, make sure <code>$GOBIN</code>
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(or <code>$HOME/bin</code> if <code>$GOBIN</code> is not set)
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is in your <code>$PATH</code> and then run
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</p>
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<pre>
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$ cd $GOROOT/src
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$ ./all.bash
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</pre>
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<p>
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If <code>all.bash</code> goes well, it will finish by printing
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</p>
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<pre>
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--- cd ../test
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N known bugs; 0 unexpected bugs
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</pre>
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<p>
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where <var>N</var> is a number that varies from release to release.
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</p>
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<h2>Writing programs</h2>
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<p>
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Given a file <code>file.go</code>, compile it using
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</p>
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<pre>
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$ 6g file.go
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</pre>
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<p>
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<code>6g</code> is the Go compiler for <code>amd64</code>; it will write the output
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in <code>file.6</code>. The ‘<code>6</code>’ identifies
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files for the <code>amd64</code> architecture.
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The identifier letters for <code>386</code> and <code>arm</code>
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are ‘<code>8</code>’ and ‘<code>5</code>’.
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That is, if you were compiling for <code>386</code>, you would use
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<code>8g</code> and the output would be named <code>file.8</code>.
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</p>
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<p>
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To link the file, use
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</p>
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<pre>
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$ 6l file.6
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</pre>
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<p>
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and to run it
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</p>
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<pre>
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$ ./6.out
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</pre>
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<p>A complete example:
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</p>
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<pre>
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$ cat >hello.go <<EOF
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package main
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import "fmt"
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func main() {
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fmt.Printf("hello, world\n")
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}
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EOF
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$ 6g hello.go
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$ 6l hello.6
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$ ./6.out
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hello, world
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$
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</pre>
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<p>
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There is no need to list <code>hello.6</code>'s package dependencies
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(in this case, package <code>fmt</code>) on the <code>6l</code>
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command line.
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The linker learns about them by reading <code>hello.6</code>.
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</p>
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<p>
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To build more complicated programs, you will probably
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want to use a
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<code>Makefile</code>.
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There are examples in places like
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<code>$GOROOT/src/cmd/godoc/Makefile</code>
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and <code>$GOROOT/src/pkg/*/Makefile</code>.
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The
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<a href="contribute.html">document</a>
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about contributing to the Go project
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gives more detail about
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the process of building and testing Go programs.
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</p>
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