mirror of
				https://github.com/caddyserver/caddy.git
				synced 2025-11-04 03:27:23 -05:00 
			
		
		
		
	The vendor/ folder was created with the help of @FiloSottile's gvt and vendorcheck. Any dependencies of Caddy plugins outside this repo are not vendored. We do not remove any unused, vendored packages because vendorcheck -u only checks using the current build configuration; i.e. packages that may be imported by files toggled by build tags of other systems. CI tests have been updated to ignore the vendor/ folder. When Go 1.9 is released, a few of the go commands should be revised to again use ./... as it will ignore the vendor folder by default.
		
			
				
	
	
		
			1992 lines
		
	
	
		
			67 KiB
		
	
	
	
		
			Go
		
	
	
	
	
	
			
		
		
	
	
			1992 lines
		
	
	
		
			67 KiB
		
	
	
	
		
			Go
		
	
	
	
	
	
// Copyright 2017 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build h2demo
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package main
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import "html/template"
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var pushTmpl = template.Must(template.New("serverpush").Parse(`
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<!DOCTYPE html>
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<meta name="viewport" content="width=device-width, initial-scale=1">
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<meta name="theme-color" content="#375EAB">
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  <title>HTTP/2 Server Push Demo</title>
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<link type="text/css" rel="stylesheet" href="/serverpush/static/style.css?{{.CacheBust}}">
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<script>
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window.initFuncs = [];
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</script>
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<script>
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function showtimes() {
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	var times = 'DOM loaded: ' + (window.performance.timing.domContentLoadedEventEnd - window.performance.timing.navigationStart) + 'ms, '
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	times += 'DOM complete (all loaded): ' + (window.performance.timing.domComplete - window.performance.timing.navigationStart) + 'ms, '
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	times += 'Load event fired: ' + (window.performance.timing.loadEventStart - window.performance.timing.navigationStart) + 'ms'
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	document.getElementById('loadtimes').innerHTML = times
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}
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</script>
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</head>
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<body onload="showtimes()">
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<div style="background:#fff9a4;padding:10px">
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Note: This page exists for demonstration purposes. For the actual cmd/go docs, go to <a href="golang.org/cmd/go">golang.org/cmd/go</a>.
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</div>
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<div style="padding:20px">
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<a href="https://{{.HTTPSHost}}/serverpush">HTTP/2 with Server Push</a> | <a href="http://{{.HTTPHost}}/serverpush">HTTP only</a>
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<div id="loadtimes"></div>
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</div>
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<div id='lowframe' style="position: fixed; bottom: 0; left: 0; height: 0; width: 100%; border-top: thin solid grey; background-color: white; overflow: auto;">
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...
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</div><!-- #lowframe -->
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						|
 | 
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<div id="topbar" class="wide"><div class="container">
 | 
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<div class="top-heading" id="heading-wide"><a href="/">The Go Programming Language</a></div>
 | 
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<div class="top-heading" id="heading-narrow"><a href="/">Go</a></div>
 | 
						|
<a href="#" id="menu-button"><span id="menu-button-arrow">▽</span></a>
 | 
						|
<form method="GET" action="/search">
 | 
						|
<div id="menu">
 | 
						|
<a href="/doc/">Documents</a>
 | 
						|
<a href="/pkg/">Packages</a>
 | 
						|
<a href="/project/">The Project</a>
 | 
						|
<a href="/help/">Help</a>
 | 
						|
<a href="/blog/">Blog</a>
 | 
						|
 | 
						|
<a id="playgroundButton" href="http://play.golang.org/" title="Show Go Playground">Play</a>
 | 
						|
 | 
						|
<input type="text" id="search" name="q" class="inactive" value="Search" placeholder="Search">
 | 
						|
</div>
 | 
						|
</form>
 | 
						|
 | 
						|
</div></div>
 | 
						|
 | 
						|
 | 
						|
<div id="playground" class="play">
 | 
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	<div class="input"><textarea class="code" spellcheck="false">package main
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 | 
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import "fmt"
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 | 
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func main() {
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						|
	fmt.Println("Hello, 世界")
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						|
}</textarea></div>
 | 
						|
	<div class="output"></div>
 | 
						|
	<div class="buttons">
 | 
						|
		<a class="run" title="Run this code [shift-enter]">Run</a>
 | 
						|
		<a class="fmt" title="Format this code">Format</a>
 | 
						|
		
 | 
						|
		<a class="share" title="Share this code">Share</a>
 | 
						|
		
 | 
						|
	</div>
 | 
						|
</div>
 | 
						|
 | 
						|
 | 
						|
<div id="page" class="wide">
 | 
						|
<div class="container">
 | 
						|
 | 
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 | 
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  <h1>Command go</h1>
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 | 
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 | 
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 | 
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 | 
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<div id="nav"></div>
 | 
						|
 | 
						|
 | 
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<!--
 | 
						|
	Copyright 2009 The Go Authors. All rights reserved.
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	Use of this source code is governed by a BSD-style
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	license that can be found in the LICENSE file.
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						|
-->
 | 
						|
<!--
 | 
						|
	Note: Static (i.e., not template-generated) href and id
 | 
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	attributes start with "pkg-" to make it impossible for
 | 
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	them to conflict with generated attributes (some of which
 | 
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	correspond to Go identifiers).
 | 
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-->
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 | 
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	<script type='text/javascript'>
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	document.ANALYSIS_DATA = null;
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	document.CALLGRAPH = null;
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	</script>
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 | 
						|
	
 | 
						|
		
 | 
						|
		<p>
 | 
						|
Go is a tool for managing Go source code.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
Usage:
 | 
						|
</p>
 | 
						|
<pre>go command [arguments]
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
The commands are:
 | 
						|
</p>
 | 
						|
<pre>build       compile packages and dependencies
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						|
clean       remove object files
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doc         show documentation for package or symbol
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env         print Go environment information
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bug         start a bug report
 | 
						|
fix         run go tool fix on packages
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fmt         run gofmt on package sources
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generate    generate Go files by processing source
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get         download and install packages and dependencies
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install     compile and install packages and dependencies
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list        list packages
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run         compile and run Go program
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test        test packages
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tool        run specified go tool
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version     print Go version
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vet         run go tool vet on packages
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</pre>
 | 
						|
<p>
 | 
						|
Use "go help [command]" for more information about a command.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
Additional help topics:
 | 
						|
</p>
 | 
						|
<pre>c           calling between Go and C
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buildmode   description of build modes
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						|
filetype    file types
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						|
gopath      GOPATH environment variable
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						|
environment environment variables
 | 
						|
importpath  import path syntax
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						|
packages    description of package lists
 | 
						|
testflag    description of testing flags
 | 
						|
testfunc    description of testing functions
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						|
</pre>
 | 
						|
<p>
 | 
						|
Use "go help [topic]" for more information about that topic.
 | 
						|
</p>
 | 
						|
<h3 id="hdr-Compile_packages_and_dependencies">Compile packages and dependencies</h3>
 | 
						|
<p>
 | 
						|
Usage:
 | 
						|
</p>
 | 
						|
<pre>go build [-o output] [-i] [build flags] [packages]
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						|
</pre>
 | 
						|
<p>
 | 
						|
Build compiles the packages named by the import paths,
 | 
						|
along with their dependencies, but it does not install the results.
 | 
						|
</p>
 | 
						|
<p>
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						|
If the arguments to build are a list of .go files, build treats
 | 
						|
them as a list of source files specifying a single package.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
When compiling a single main package, build writes
 | 
						|
the resulting executable to an output file named after
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						|
the first source file ('go build ed.go rx.go' writes 'ed' or 'ed.exe')
 | 
						|
or the source code directory ('go build unix/sam' writes 'sam' or 'sam.exe').
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						|
The '.exe' suffix is added when writing a Windows executable.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
When compiling multiple packages or a single non-main package,
 | 
						|
build compiles the packages but discards the resulting object,
 | 
						|
serving only as a check that the packages can be built.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
When compiling packages, build ignores files that end in '_test.go'.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
The -o flag, only allowed when compiling a single package,
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						|
forces build to write the resulting executable or object
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						|
to the named output file, instead of the default behavior described
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						|
in the last two paragraphs.
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						|
</p>
 | 
						|
<p>
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						|
The -i flag installs the packages that are dependencies of the target.
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						|
</p>
 | 
						|
<p>
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						|
The build flags are shared by the build, clean, get, install, list, run,
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						|
and test commands:
 | 
						|
</p>
 | 
						|
<pre>-a
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	force rebuilding of packages that are already up-to-date.
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						|
-n
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	print the commands but do not run them.
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						|
-p n
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	the number of programs, such as build commands or
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						|
	test binaries, that can be run in parallel.
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	The default is the number of CPUs available.
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						|
-race
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	enable data race detection.
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	Supported only on linux/amd64, freebsd/amd64, darwin/amd64 and windows/amd64.
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						|
-msan
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	enable interoperation with memory sanitizer.
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	Supported only on linux/amd64,
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	and only with Clang/LLVM as the host C compiler.
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						|
-v
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	print the names of packages as they are compiled.
 | 
						|
-work
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						|
	print the name of the temporary work directory and
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						|
	do not delete it when exiting.
 | 
						|
-x
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	print the commands.
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						|
 | 
						|
-asmflags 'flag list'
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	arguments to pass on each go tool asm invocation.
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-buildmode mode
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	build mode to use. See 'go help buildmode' for more.
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-compiler name
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	name of compiler to use, as in runtime.Compiler (gccgo or gc).
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						|
-gccgoflags 'arg list'
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	arguments to pass on each gccgo compiler/linker invocation.
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						|
-gcflags 'arg list'
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	arguments to pass on each go tool compile invocation.
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						|
-installsuffix suffix
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	a suffix to use in the name of the package installation directory,
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	in order to keep output separate from default builds.
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						|
	If using the -race flag, the install suffix is automatically set to race
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						|
	or, if set explicitly, has _race appended to it.  Likewise for the -msan
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	flag.  Using a -buildmode option that requires non-default compile flags
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	has a similar effect.
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						|
-ldflags 'flag list'
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	arguments to pass on each go tool link invocation.
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						|
-linkshared
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	link against shared libraries previously created with
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	-buildmode=shared.
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						|
-pkgdir dir
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						|
	install and load all packages from dir instead of the usual locations.
 | 
						|
	For example, when building with a non-standard configuration,
 | 
						|
	use -pkgdir to keep generated packages in a separate location.
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						|
-tags 'tag list'
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	a list of build tags to consider satisfied during the build.
 | 
						|
	For more information about build tags, see the description of
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	build constraints in the documentation for the go/build package.
 | 
						|
-toolexec 'cmd args'
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	a program to use to invoke toolchain programs like vet and asm.
 | 
						|
	For example, instead of running asm, the go command will run
 | 
						|
	'cmd args /path/to/asm <arguments for asm>'.
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
The list flags accept a space-separated list of strings. To embed spaces
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						|
in an element in the list, surround it with either single or double quotes.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
For more about specifying packages, see 'go help packages'.
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For more about where packages and binaries are installed,
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run 'go help gopath'.
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						|
For more about calling between Go and C/C++, run 'go help c'.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
Note: Build adheres to certain conventions such as those described
 | 
						|
by 'go help gopath'. Not all projects can follow these conventions,
 | 
						|
however. Installations that have their own conventions or that use
 | 
						|
a separate software build system may choose to use lower-level
 | 
						|
invocations such as 'go tool compile' and 'go tool link' to avoid
 | 
						|
some of the overheads and design decisions of the build tool.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
See also: go install, go get, go clean.
 | 
						|
</p>
 | 
						|
<h3 id="hdr-Remove_object_files">Remove object files</h3>
 | 
						|
<p>
 | 
						|
Usage:
 | 
						|
</p>
 | 
						|
<pre>go clean [-i] [-r] [-n] [-x] [build flags] [packages]
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
Clean removes object files from package source directories.
 | 
						|
The go command builds most objects in a temporary directory,
 | 
						|
so go clean is mainly concerned with object files left by other
 | 
						|
tools or by manual invocations of go build.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
Specifically, clean removes the following files from each of the
 | 
						|
source directories corresponding to the import paths:
 | 
						|
</p>
 | 
						|
<pre>_obj/            old object directory, left from Makefiles
 | 
						|
_test/           old test directory, left from Makefiles
 | 
						|
_testmain.go     old gotest file, left from Makefiles
 | 
						|
test.out         old test log, left from Makefiles
 | 
						|
build.out        old test log, left from Makefiles
 | 
						|
*.[568ao]        object files, left from Makefiles
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						|
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						|
DIR(.exe)        from go build
 | 
						|
DIR.test(.exe)   from go test -c
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						|
MAINFILE(.exe)   from go build MAINFILE.go
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						|
*.so             from SWIG
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
In the list, DIR represents the final path element of the
 | 
						|
directory, and MAINFILE is the base name of any Go source
 | 
						|
file in the directory that is not included when building
 | 
						|
the package.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
The -i flag causes clean to remove the corresponding installed
 | 
						|
archive or binary (what 'go install' would create).
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
The -n flag causes clean to print the remove commands it would execute,
 | 
						|
but not run them.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
The -r flag causes clean to be applied recursively to all the
 | 
						|
dependencies of the packages named by the import paths.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
The -x flag causes clean to print remove commands as it executes them.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
For more about build flags, see 'go help build'.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
For more about specifying packages, see 'go help packages'.
 | 
						|
</p>
 | 
						|
<h3 id="hdr-Show_documentation_for_package_or_symbol">Show documentation for package or symbol</h3>
 | 
						|
<p>
 | 
						|
Usage:
 | 
						|
</p>
 | 
						|
<pre>go doc [-u] [-c] [package|[package.]symbol[.method]]
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
Doc prints the documentation comments associated with the item identified by its
 | 
						|
arguments (a package, const, func, type, var, or method) followed by a one-line
 | 
						|
summary of each of the first-level items "under" that item (package-level
 | 
						|
declarations for a package, methods for a type, etc.).
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
Doc accepts zero, one, or two arguments.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
Given no arguments, that is, when run as
 | 
						|
</p>
 | 
						|
<pre>go doc
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
it prints the package documentation for the package in the current directory.
 | 
						|
If the package is a command (package main), the exported symbols of the package
 | 
						|
are elided from the presentation unless the -cmd flag is provided.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
When run with one argument, the argument is treated as a Go-syntax-like
 | 
						|
representation of the item to be documented. What the argument selects depends
 | 
						|
on what is installed in GOROOT and GOPATH, as well as the form of the argument,
 | 
						|
which is schematically one of these:
 | 
						|
</p>
 | 
						|
<pre>go doc <pkg>
 | 
						|
go doc <sym>[.<method>]
 | 
						|
go doc [<pkg>.]<sym>[.<method>]
 | 
						|
go doc [<pkg>.][<sym>.]<method>
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
The first item in this list matched by the argument is the one whose documentation
 | 
						|
is printed. (See the examples below.) However, if the argument starts with a capital
 | 
						|
letter it is assumed to identify a symbol or method in the current directory.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
For packages, the order of scanning is determined lexically in breadth-first order.
 | 
						|
That is, the package presented is the one that matches the search and is nearest
 | 
						|
the root and lexically first at its level of the hierarchy.  The GOROOT tree is
 | 
						|
always scanned in its entirety before GOPATH.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
If there is no package specified or matched, the package in the current
 | 
						|
directory is selected, so "go doc Foo" shows the documentation for symbol Foo in
 | 
						|
the current package.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
The package path must be either a qualified path or a proper suffix of a
 | 
						|
path. The go tool's usual package mechanism does not apply: package path
 | 
						|
elements like . and ... are not implemented by go doc.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
When run with two arguments, the first must be a full package path (not just a
 | 
						|
suffix), and the second is a symbol or symbol and method; this is similar to the
 | 
						|
syntax accepted by godoc:
 | 
						|
</p>
 | 
						|
<pre>go doc <pkg> <sym>[.<method>]
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
In all forms, when matching symbols, lower-case letters in the argument match
 | 
						|
either case but upper-case letters match exactly. This means that there may be
 | 
						|
multiple matches of a lower-case argument in a package if different symbols have
 | 
						|
different cases. If this occurs, documentation for all matches is printed.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
Examples:
 | 
						|
</p>
 | 
						|
<pre>go doc
 | 
						|
	Show documentation for current package.
 | 
						|
go doc Foo
 | 
						|
	Show documentation for Foo in the current package.
 | 
						|
	(Foo starts with a capital letter so it cannot match
 | 
						|
	a package path.)
 | 
						|
go doc encoding/json
 | 
						|
	Show documentation for the encoding/json package.
 | 
						|
go doc json
 | 
						|
	Shorthand for encoding/json.
 | 
						|
go doc json.Number (or go doc json.number)
 | 
						|
	Show documentation and method summary for json.Number.
 | 
						|
go doc json.Number.Int64 (or go doc json.number.int64)
 | 
						|
	Show documentation for json.Number's Int64 method.
 | 
						|
go doc cmd/doc
 | 
						|
	Show package docs for the doc command.
 | 
						|
go doc -cmd cmd/doc
 | 
						|
	Show package docs and exported symbols within the doc command.
 | 
						|
go doc template.new
 | 
						|
	Show documentation for html/template's New function.
 | 
						|
	(html/template is lexically before text/template)
 | 
						|
go doc text/template.new # One argument
 | 
						|
	Show documentation for text/template's New function.
 | 
						|
go doc text/template new # Two arguments
 | 
						|
	Show documentation for text/template's New function.
 | 
						|
 | 
						|
At least in the current tree, these invocations all print the
 | 
						|
documentation for json.Decoder's Decode method:
 | 
						|
 | 
						|
go doc json.Decoder.Decode
 | 
						|
go doc json.decoder.decode
 | 
						|
go doc json.decode
 | 
						|
cd go/src/encoding/json; go doc decode
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
Flags:
 | 
						|
</p>
 | 
						|
<pre>-c
 | 
						|
	Respect case when matching symbols.
 | 
						|
-cmd
 | 
						|
	Treat a command (package main) like a regular package.
 | 
						|
	Otherwise package main's exported symbols are hidden
 | 
						|
	when showing the package's top-level documentation.
 | 
						|
-u
 | 
						|
	Show documentation for unexported as well as exported
 | 
						|
	symbols and methods.
 | 
						|
</pre>
 | 
						|
<h3 id="hdr-Print_Go_environment_information">Print Go environment information</h3>
 | 
						|
<p>
 | 
						|
Usage:
 | 
						|
</p>
 | 
						|
<pre>go env [var ...]
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
Env prints Go environment information.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
By default env prints information as a shell script
 | 
						|
(on Windows, a batch file).  If one or more variable
 | 
						|
names is given as arguments,  env prints the value of
 | 
						|
each named variable on its own line.
 | 
						|
</p>
 | 
						|
<h3 id="hdr-Start_a_bug_report">Start a bug report</h3>
 | 
						|
<p>
 | 
						|
Usage:
 | 
						|
</p>
 | 
						|
<pre>go bug
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
Bug opens the default browser and starts a new bug report.
 | 
						|
The report includes useful system information.
 | 
						|
</p>
 | 
						|
<h3 id="hdr-Run_go_tool_fix_on_packages">Run go tool fix on packages</h3>
 | 
						|
<p>
 | 
						|
Usage:
 | 
						|
</p>
 | 
						|
<pre>go fix [packages]
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
Fix runs the Go fix command on the packages named by the import paths.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
For more about fix, see 'go doc cmd/fix'.
 | 
						|
For more about specifying packages, see 'go help packages'.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
To run fix with specific options, run 'go tool fix'.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
See also: go fmt, go vet.
 | 
						|
</p>
 | 
						|
<h3 id="hdr-Run_gofmt_on_package_sources">Run gofmt on package sources</h3>
 | 
						|
<p>
 | 
						|
Usage:
 | 
						|
</p>
 | 
						|
<pre>go fmt [-n] [-x] [packages]
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
Fmt runs the command 'gofmt -l -w' on the packages named
 | 
						|
by the import paths.  It prints the names of the files that are modified.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
For more about gofmt, see 'go doc cmd/gofmt'.
 | 
						|
For more about specifying packages, see 'go help packages'.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
The -n flag prints commands that would be executed.
 | 
						|
The -x flag prints commands as they are executed.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
To run gofmt with specific options, run gofmt itself.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
See also: go fix, go vet.
 | 
						|
</p>
 | 
						|
<h3 id="hdr-Generate_Go_files_by_processing_source">Generate Go files by processing source</h3>
 | 
						|
<p>
 | 
						|
Usage:
 | 
						|
</p>
 | 
						|
<pre>go generate [-run regexp] [-n] [-v] [-x] [build flags] [file.go... | packages]
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
Generate runs commands described by directives within existing
 | 
						|
files. Those commands can run any process but the intent is to
 | 
						|
create or update Go source files.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
Go generate is never run automatically by go build, go get, go test,
 | 
						|
and so on. It must be run explicitly.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
Go generate scans the file for directives, which are lines of
 | 
						|
the form,
 | 
						|
</p>
 | 
						|
<pre>//go:generate command argument...
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
(note: no leading spaces and no space in "//go") where command
 | 
						|
is the generator to be run, corresponding to an executable file
 | 
						|
that can be run locally. It must either be in the shell path
 | 
						|
(gofmt), a fully qualified path (/usr/you/bin/mytool), or a
 | 
						|
command alias, described below.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
Note that go generate does not parse the file, so lines that look
 | 
						|
like directives in comments or multiline strings will be treated
 | 
						|
as directives.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
The arguments to the directive are space-separated tokens or
 | 
						|
double-quoted strings passed to the generator as individual
 | 
						|
arguments when it is run.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
Quoted strings use Go syntax and are evaluated before execution; a
 | 
						|
quoted string appears as a single argument to the generator.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
Go generate sets several variables when it runs the generator:
 | 
						|
</p>
 | 
						|
<pre>$GOARCH
 | 
						|
	The execution architecture (arm, amd64, etc.)
 | 
						|
$GOOS
 | 
						|
	The execution operating system (linux, windows, etc.)
 | 
						|
$GOFILE
 | 
						|
	The base name of the file.
 | 
						|
$GOLINE
 | 
						|
	The line number of the directive in the source file.
 | 
						|
$GOPACKAGE
 | 
						|
	The name of the package of the file containing the directive.
 | 
						|
$DOLLAR
 | 
						|
	A dollar sign.
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
Other than variable substitution and quoted-string evaluation, no
 | 
						|
special processing such as "globbing" is performed on the command
 | 
						|
line.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
As a last step before running the command, any invocations of any
 | 
						|
environment variables with alphanumeric names, such as $GOFILE or
 | 
						|
$HOME, are expanded throughout the command line. The syntax for
 | 
						|
variable expansion is $NAME on all operating systems.  Due to the
 | 
						|
order of evaluation, variables are expanded even inside quoted
 | 
						|
strings. If the variable NAME is not set, $NAME expands to the
 | 
						|
empty string.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
A directive of the form,
 | 
						|
</p>
 | 
						|
<pre>//go:generate -command xxx args...
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
specifies, for the remainder of this source file only, that the
 | 
						|
string xxx represents the command identified by the arguments. This
 | 
						|
can be used to create aliases or to handle multiword generators.
 | 
						|
For example,
 | 
						|
</p>
 | 
						|
<pre>//go:generate -command foo go tool foo
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
specifies that the command "foo" represents the generator
 | 
						|
"go tool foo".
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
Generate processes packages in the order given on the command line,
 | 
						|
one at a time. If the command line lists .go files, they are treated
 | 
						|
as a single package. Within a package, generate processes the
 | 
						|
source files in a package in file name order, one at a time. Within
 | 
						|
a source file, generate runs generators in the order they appear
 | 
						|
in the file, one at a time.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
If any generator returns an error exit status, "go generate" skips
 | 
						|
all further processing for that package.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
The generator is run in the package's source directory.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
Go generate accepts one specific flag:
 | 
						|
</p>
 | 
						|
<pre>-run=""
 | 
						|
	if non-empty, specifies a regular expression to select
 | 
						|
	directives whose full original source text (excluding
 | 
						|
	any trailing spaces and final newline) matches the
 | 
						|
	expression.
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
It also accepts the standard build flags including -v, -n, and -x.
 | 
						|
The -v flag prints the names of packages and files as they are
 | 
						|
processed.
 | 
						|
The -n flag prints commands that would be executed.
 | 
						|
The -x flag prints commands as they are executed.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
For more about build flags, see 'go help build'.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
For more about specifying packages, see 'go help packages'.
 | 
						|
</p>
 | 
						|
<h3 id="hdr-Download_and_install_packages_and_dependencies">Download and install packages and dependencies</h3>
 | 
						|
<p>
 | 
						|
Usage:
 | 
						|
</p>
 | 
						|
<pre>go get [-d] [-f] [-fix] [-insecure] [-t] [-u] [build flags] [packages]
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
Get downloads the packages named by the import paths, along with their
 | 
						|
dependencies. It then installs the named packages, like 'go install'.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
The -d flag instructs get to stop after downloading the packages; that is,
 | 
						|
it instructs get not to install the packages.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
The -f flag, valid only when -u is set, forces get -u not to verify that
 | 
						|
each package has been checked out from the source control repository
 | 
						|
implied by its import path. This can be useful if the source is a local fork
 | 
						|
of the original.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
The -fix flag instructs get to run the fix tool on the downloaded packages
 | 
						|
before resolving dependencies or building the code.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
The -insecure flag permits fetching from repositories and resolving
 | 
						|
custom domains using insecure schemes such as HTTP. Use with caution.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
The -t flag instructs get to also download the packages required to build
 | 
						|
the tests for the specified packages.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
The -u flag instructs get to use the network to update the named packages
 | 
						|
and their dependencies.  By default, get uses the network to check out
 | 
						|
missing packages but does not use it to look for updates to existing packages.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
The -v flag enables verbose progress and debug output.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
Get also accepts build flags to control the installation. See 'go help build'.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
When checking out a new package, get creates the target directory
 | 
						|
GOPATH/src/<import-path>. If the GOPATH contains multiple entries,
 | 
						|
get uses the first one. For more details see: 'go help gopath'.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
When checking out or updating a package, get looks for a branch or tag
 | 
						|
that matches the locally installed version of Go. The most important
 | 
						|
rule is that if the local installation is running version "go1", get
 | 
						|
searches for a branch or tag named "go1". If no such version exists it
 | 
						|
retrieves the most recent version of the package.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
When go get checks out or updates a Git repository,
 | 
						|
it also updates any git submodules referenced by the repository.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
Get never checks out or updates code stored in vendor directories.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
For more about specifying packages, see 'go help packages'.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
For more about how 'go get' finds source code to
 | 
						|
download, see 'go help importpath'.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
See also: go build, go install, go clean.
 | 
						|
</p>
 | 
						|
<h3 id="hdr-Compile_and_install_packages_and_dependencies">Compile and install packages and dependencies</h3>
 | 
						|
<p>
 | 
						|
Usage:
 | 
						|
</p>
 | 
						|
<pre>go install [build flags] [packages]
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
Install compiles and installs the packages named by the import paths,
 | 
						|
along with their dependencies.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
For more about the build flags, see 'go help build'.
 | 
						|
For more about specifying packages, see 'go help packages'.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
See also: go build, go get, go clean.
 | 
						|
</p>
 | 
						|
<h3 id="hdr-List_packages">List packages</h3>
 | 
						|
<p>
 | 
						|
Usage:
 | 
						|
</p>
 | 
						|
<pre>go list [-e] [-f format] [-json] [build flags] [packages]
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
List lists the packages named by the import paths, one per line.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
The default output shows the package import path:
 | 
						|
</p>
 | 
						|
<pre>bytes
 | 
						|
encoding/json
 | 
						|
github.com/gorilla/mux
 | 
						|
golang.org/x/net/html
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
The -f flag specifies an alternate format for the list, using the
 | 
						|
syntax of package template.  The default output is equivalent to -f
 | 
						|
''. The struct being passed to the template is:
 | 
						|
</p>
 | 
						|
<pre>type Package struct {
 | 
						|
    Dir           string // directory containing package sources
 | 
						|
    ImportPath    string // import path of package in dir
 | 
						|
    ImportComment string // path in import comment on package statement
 | 
						|
    Name          string // package name
 | 
						|
    Doc           string // package documentation string
 | 
						|
    Target        string // install path
 | 
						|
    Shlib         string // the shared library that contains this package (only set when -linkshared)
 | 
						|
    Goroot        bool   // is this package in the Go root?
 | 
						|
    Standard      bool   // is this package part of the standard Go library?
 | 
						|
    Stale         bool   // would 'go install' do anything for this package?
 | 
						|
    StaleReason   string // explanation for Stale==true
 | 
						|
    Root          string // Go root or Go path dir containing this package
 | 
						|
    ConflictDir   string // this directory shadows Dir in $GOPATH
 | 
						|
    BinaryOnly    bool   // binary-only package: cannot be recompiled from sources
 | 
						|
 | 
						|
    // Source files
 | 
						|
    GoFiles        []string // .go source files (excluding CgoFiles, TestGoFiles, XTestGoFiles)
 | 
						|
    CgoFiles       []string // .go sources files that import "C"
 | 
						|
    IgnoredGoFiles []string // .go sources ignored due to build constraints
 | 
						|
    CFiles         []string // .c source files
 | 
						|
    CXXFiles       []string // .cc, .cxx and .cpp source files
 | 
						|
    MFiles         []string // .m source files
 | 
						|
    HFiles         []string // .h, .hh, .hpp and .hxx source files
 | 
						|
    FFiles         []string // .f, .F, .for and .f90 Fortran source files
 | 
						|
    SFiles         []string // .s source files
 | 
						|
    SwigFiles      []string // .swig files
 | 
						|
    SwigCXXFiles   []string // .swigcxx files
 | 
						|
    SysoFiles      []string // .syso object files to add to archive
 | 
						|
    TestGoFiles    []string // _test.go files in package
 | 
						|
    XTestGoFiles   []string // _test.go files outside package
 | 
						|
 | 
						|
    // Cgo directives
 | 
						|
    CgoCFLAGS    []string // cgo: flags for C compiler
 | 
						|
    CgoCPPFLAGS  []string // cgo: flags for C preprocessor
 | 
						|
    CgoCXXFLAGS  []string // cgo: flags for C++ compiler
 | 
						|
    CgoFFLAGS    []string // cgo: flags for Fortran compiler
 | 
						|
    CgoLDFLAGS   []string // cgo: flags for linker
 | 
						|
    CgoPkgConfig []string // cgo: pkg-config names
 | 
						|
 | 
						|
    // Dependency information
 | 
						|
    Imports      []string // import paths used by this package
 | 
						|
    Deps         []string // all (recursively) imported dependencies
 | 
						|
    TestImports  []string // imports from TestGoFiles
 | 
						|
    XTestImports []string // imports from XTestGoFiles
 | 
						|
 | 
						|
    // Error information
 | 
						|
    Incomplete bool            // this package or a dependency has an error
 | 
						|
    Error      *PackageError   // error loading package
 | 
						|
    DepsErrors []*PackageError // errors loading dependencies
 | 
						|
}
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
Packages stored in vendor directories report an ImportPath that includes the
 | 
						|
path to the vendor directory (for example, "d/vendor/p" instead of "p"),
 | 
						|
so that the ImportPath uniquely identifies a given copy of a package.
 | 
						|
The Imports, Deps, TestImports, and XTestImports lists also contain these
 | 
						|
expanded imports paths. See golang.org/s/go15vendor for more about vendoring.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
The error information, if any, is
 | 
						|
</p>
 | 
						|
<pre>type PackageError struct {
 | 
						|
    ImportStack   []string // shortest path from package named on command line to this one
 | 
						|
    Pos           string   // position of error (if present, file:line:col)
 | 
						|
    Err           string   // the error itself
 | 
						|
}
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
The template function "join" calls strings.Join.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
The template function "context" returns the build context, defined as:
 | 
						|
</p>
 | 
						|
<pre>type Context struct {
 | 
						|
	GOARCH        string   // target architecture
 | 
						|
	GOOS          string   // target operating system
 | 
						|
	GOROOT        string   // Go root
 | 
						|
	GOPATH        string   // Go path
 | 
						|
	CgoEnabled    bool     // whether cgo can be used
 | 
						|
	UseAllFiles   bool     // use files regardless of +build lines, file names
 | 
						|
	Compiler      string   // compiler to assume when computing target paths
 | 
						|
	BuildTags     []string // build constraints to match in +build lines
 | 
						|
	ReleaseTags   []string // releases the current release is compatible with
 | 
						|
	InstallSuffix string   // suffix to use in the name of the install dir
 | 
						|
}
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
For more information about the meaning of these fields see the documentation
 | 
						|
for the go/build package's Context type.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
The -json flag causes the package data to be printed in JSON format
 | 
						|
instead of using the template format.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
The -e flag changes the handling of erroneous packages, those that
 | 
						|
cannot be found or are malformed.  By default, the list command
 | 
						|
prints an error to standard error for each erroneous package and
 | 
						|
omits the packages from consideration during the usual printing.
 | 
						|
With the -e flag, the list command never prints errors to standard
 | 
						|
error and instead processes the erroneous packages with the usual
 | 
						|
printing.  Erroneous packages will have a non-empty ImportPath and
 | 
						|
a non-nil Error field; other information may or may not be missing
 | 
						|
(zeroed).
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
For more about build flags, see 'go help build'.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
For more about specifying packages, see 'go help packages'.
 | 
						|
</p>
 | 
						|
<h3 id="hdr-Compile_and_run_Go_program">Compile and run Go program</h3>
 | 
						|
<p>
 | 
						|
Usage:
 | 
						|
</p>
 | 
						|
<pre>go run [build flags] [-exec xprog] gofiles... [arguments...]
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
Run compiles and runs the main package comprising the named Go source files.
 | 
						|
A Go source file is defined to be a file ending in a literal ".go" suffix.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
By default, 'go run' runs the compiled binary directly: 'a.out arguments...'.
 | 
						|
If the -exec flag is given, 'go run' invokes the binary using xprog:
 | 
						|
</p>
 | 
						|
<pre>'xprog a.out arguments...'.
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
If the -exec flag is not given, GOOS or GOARCH is different from the system
 | 
						|
default, and a program named go_$GOOS_$GOARCH_exec can be found
 | 
						|
on the current search path, 'go run' invokes the binary using that program,
 | 
						|
for example 'go_nacl_386_exec a.out arguments...'. This allows execution of
 | 
						|
cross-compiled programs when a simulator or other execution method is
 | 
						|
available.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
For more about build flags, see 'go help build'.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
See also: go build.
 | 
						|
</p>
 | 
						|
<h3 id="hdr-Test_packages">Test packages</h3>
 | 
						|
<p>
 | 
						|
Usage:
 | 
						|
</p>
 | 
						|
<pre>go test [build/test flags] [packages] [build/test flags & test binary flags]
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
'Go test' automates testing the packages named by the import paths.
 | 
						|
It prints a summary of the test results in the format:
 | 
						|
</p>
 | 
						|
<pre>ok   archive/tar   0.011s
 | 
						|
FAIL archive/zip   0.022s
 | 
						|
ok   compress/gzip 0.033s
 | 
						|
...
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
followed by detailed output for each failed package.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
'Go test' recompiles each package along with any files with names matching
 | 
						|
the file pattern "*_test.go".
 | 
						|
Files whose names begin with "_" (including "_test.go") or "." are ignored.
 | 
						|
These additional files can contain test functions, benchmark functions, and
 | 
						|
example functions.  See 'go help testfunc' for more.
 | 
						|
Each listed package causes the execution of a separate test binary.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
Test files that declare a package with the suffix "_test" will be compiled as a
 | 
						|
separate package, and then linked and run with the main test binary.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
The go tool will ignore a directory named "testdata", making it available
 | 
						|
to hold ancillary data needed by the tests.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
By default, go test needs no arguments.  It compiles and tests the package
 | 
						|
with source in the current directory, including tests, and runs the tests.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
The package is built in a temporary directory so it does not interfere with the
 | 
						|
non-test installation.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
In addition to the build flags, the flags handled by 'go test' itself are:
 | 
						|
</p>
 | 
						|
<pre>-args
 | 
						|
    Pass the remainder of the command line (everything after -args)
 | 
						|
    to the test binary, uninterpreted and unchanged.
 | 
						|
    Because this flag consumes the remainder of the command line,
 | 
						|
    the package list (if present) must appear before this flag.
 | 
						|
 | 
						|
-c
 | 
						|
    Compile the test binary to pkg.test but do not run it
 | 
						|
    (where pkg is the last element of the package's import path).
 | 
						|
    The file name can be changed with the -o flag.
 | 
						|
 | 
						|
-exec xprog
 | 
						|
    Run the test binary using xprog. The behavior is the same as
 | 
						|
    in 'go run'. See 'go help run' for details.
 | 
						|
 | 
						|
-i
 | 
						|
    Install packages that are dependencies of the test.
 | 
						|
    Do not run the test.
 | 
						|
 | 
						|
-o file
 | 
						|
    Compile the test binary to the named file.
 | 
						|
    The test still runs (unless -c or -i is specified).
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
The test binary also accepts flags that control execution of the test; these
 | 
						|
flags are also accessible by 'go test'. See 'go help testflag' for details.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
For more about build flags, see 'go help build'.
 | 
						|
For more about specifying packages, see 'go help packages'.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
See also: go build, go vet.
 | 
						|
</p>
 | 
						|
<h3 id="hdr-Run_specified_go_tool">Run specified go tool</h3>
 | 
						|
<p>
 | 
						|
Usage:
 | 
						|
</p>
 | 
						|
<pre>go tool [-n] command [args...]
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
Tool runs the go tool command identified by the arguments.
 | 
						|
With no arguments it prints the list of known tools.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
The -n flag causes tool to print the command that would be
 | 
						|
executed but not execute it.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
For more about each tool command, see 'go tool command -h'.
 | 
						|
</p>
 | 
						|
<h3 id="hdr-Print_Go_version">Print Go version</h3>
 | 
						|
<p>
 | 
						|
Usage:
 | 
						|
</p>
 | 
						|
<pre>go version
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
Version prints the Go version, as reported by runtime.Version.
 | 
						|
</p>
 | 
						|
<h3 id="hdr-Run_go_tool_vet_on_packages">Run go tool vet on packages</h3>
 | 
						|
<p>
 | 
						|
Usage:
 | 
						|
</p>
 | 
						|
<pre>go vet [-n] [-x] [build flags] [packages]
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
Vet runs the Go vet command on the packages named by the import paths.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
For more about vet, see 'go doc cmd/vet'.
 | 
						|
For more about specifying packages, see 'go help packages'.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
To run the vet tool with specific options, run 'go tool vet'.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
The -n flag prints commands that would be executed.
 | 
						|
The -x flag prints commands as they are executed.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
For more about build flags, see 'go help build'.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
See also: go fmt, go fix.
 | 
						|
</p>
 | 
						|
<h3 id="hdr-Calling_between_Go_and_C">Calling between Go and C</h3>
 | 
						|
<p>
 | 
						|
There are two different ways to call between Go and C/C++ code.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
The first is the cgo tool, which is part of the Go distribution.  For
 | 
						|
information on how to use it see the cgo documentation (go doc cmd/cgo).
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
The second is the SWIG program, which is a general tool for
 | 
						|
interfacing between languages.  For information on SWIG see
 | 
						|
<a href="http://swig.org/">http://swig.org/</a>.  When running go build, any file with a .swig
 | 
						|
extension will be passed to SWIG.  Any file with a .swigcxx extension
 | 
						|
will be passed to SWIG with the -c++ option.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
When either cgo or SWIG is used, go build will pass any .c, .m, .s,
 | 
						|
or .S files to the C compiler, and any .cc, .cpp, .cxx files to the C++
 | 
						|
compiler.  The CC or CXX environment variables may be set to determine
 | 
						|
the C or C++ compiler, respectively, to use.
 | 
						|
</p>
 | 
						|
<h3 id="hdr-Description_of_build_modes">Description of build modes</h3>
 | 
						|
<p>
 | 
						|
The 'go build' and 'go install' commands take a -buildmode argument which
 | 
						|
indicates which kind of object file is to be built. Currently supported values
 | 
						|
are:
 | 
						|
</p>
 | 
						|
<pre>-buildmode=archive
 | 
						|
	Build the listed non-main packages into .a files. Packages named
 | 
						|
	main are ignored.
 | 
						|
 | 
						|
-buildmode=c-archive
 | 
						|
	Build the listed main package, plus all packages it imports,
 | 
						|
	into a C archive file. The only callable symbols will be those
 | 
						|
	functions exported using a cgo //export comment. Requires
 | 
						|
	exactly one main package to be listed.
 | 
						|
 | 
						|
-buildmode=c-shared
 | 
						|
	Build the listed main packages, plus all packages that they
 | 
						|
	import, into C shared libraries. The only callable symbols will
 | 
						|
	be those functions exported using a cgo //export comment.
 | 
						|
	Non-main packages are ignored.
 | 
						|
 | 
						|
-buildmode=default
 | 
						|
	Listed main packages are built into executables and listed
 | 
						|
	non-main packages are built into .a files (the default
 | 
						|
	behavior).
 | 
						|
 | 
						|
-buildmode=shared
 | 
						|
	Combine all the listed non-main packages into a single shared
 | 
						|
	library that will be used when building with the -linkshared
 | 
						|
	option. Packages named main are ignored.
 | 
						|
 | 
						|
-buildmode=exe
 | 
						|
	Build the listed main packages and everything they import into
 | 
						|
	executables. Packages not named main are ignored.
 | 
						|
 | 
						|
-buildmode=pie
 | 
						|
	Build the listed main packages and everything they import into
 | 
						|
	position independent executables (PIE). Packages not named
 | 
						|
	main are ignored.
 | 
						|
 | 
						|
-buildmode=plugin
 | 
						|
	Build the listed main packages, plus all packages that they
 | 
						|
	import, into a Go plugin. Packages not named main are ignored.
 | 
						|
</pre>
 | 
						|
<h3 id="hdr-File_types">File types</h3>
 | 
						|
<p>
 | 
						|
The go command examines the contents of a restricted set of files
 | 
						|
in each directory. It identifies which files to examine based on
 | 
						|
the extension of the file name. These extensions are:
 | 
						|
</p>
 | 
						|
<pre>.go
 | 
						|
	Go source files.
 | 
						|
.c, .h
 | 
						|
	C source files.
 | 
						|
	If the package uses cgo or SWIG, these will be compiled with the
 | 
						|
	OS-native compiler (typically gcc); otherwise they will
 | 
						|
	trigger an error.
 | 
						|
.cc, .cpp, .cxx, .hh, .hpp, .hxx
 | 
						|
	C++ source files. Only useful with cgo or SWIG, and always
 | 
						|
	compiled with the OS-native compiler.
 | 
						|
.m
 | 
						|
	Objective-C source files. Only useful with cgo, and always
 | 
						|
	compiled with the OS-native compiler.
 | 
						|
.s, .S
 | 
						|
	Assembler source files.
 | 
						|
	If the package uses cgo or SWIG, these will be assembled with the
 | 
						|
	OS-native assembler (typically gcc (sic)); otherwise they
 | 
						|
	will be assembled with the Go assembler.
 | 
						|
.swig, .swigcxx
 | 
						|
	SWIG definition files.
 | 
						|
.syso
 | 
						|
	System object files.
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
Files of each of these types except .syso may contain build
 | 
						|
constraints, but the go command stops scanning for build constraints
 | 
						|
at the first item in the file that is not a blank line or //-style
 | 
						|
line comment. See the go/build package documentation for
 | 
						|
more details.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
Non-test Go source files can also include a //go:binary-only-package
 | 
						|
comment, indicating that the package sources are included
 | 
						|
for documentation only and must not be used to build the
 | 
						|
package binary. This enables distribution of Go packages in
 | 
						|
their compiled form alone. See the go/build package documentation
 | 
						|
for more details.
 | 
						|
</p>
 | 
						|
<h3 id="hdr-GOPATH_environment_variable">GOPATH environment variable</h3>
 | 
						|
<p>
 | 
						|
The Go path is used to resolve import statements.
 | 
						|
It is implemented by and documented in the go/build package.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
The GOPATH environment variable lists places to look for Go code.
 | 
						|
On Unix, the value is a colon-separated string.
 | 
						|
On Windows, the value is a semicolon-separated string.
 | 
						|
On Plan 9, the value is a list.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
If the environment variable is unset, GOPATH defaults
 | 
						|
to a subdirectory named "go" in the user's home directory
 | 
						|
($HOME/go on Unix, %USERPROFILE%\go on Windows),
 | 
						|
unless that directory holds a Go distribution.
 | 
						|
Run "go env GOPATH" to see the current GOPATH.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
See <a href="https://golang.org/wiki/SettingGOPATH">https://golang.org/wiki/SettingGOPATH</a> to set a custom GOPATH.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
Each directory listed in GOPATH must have a prescribed structure:
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
The src directory holds source code.  The path below src
 | 
						|
determines the import path or executable name.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
The pkg directory holds installed package objects.
 | 
						|
As in the Go tree, each target operating system and
 | 
						|
architecture pair has its own subdirectory of pkg
 | 
						|
(pkg/GOOS_GOARCH).
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
If DIR is a directory listed in the GOPATH, a package with
 | 
						|
source in DIR/src/foo/bar can be imported as "foo/bar" and
 | 
						|
has its compiled form installed to "DIR/pkg/GOOS_GOARCH/foo/bar.a".
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
The bin directory holds compiled commands.
 | 
						|
Each command is named for its source directory, but only
 | 
						|
the final element, not the entire path.  That is, the
 | 
						|
command with source in DIR/src/foo/quux is installed into
 | 
						|
DIR/bin/quux, not DIR/bin/foo/quux.  The "foo/" prefix is stripped
 | 
						|
so that you can add DIR/bin to your PATH to get at the
 | 
						|
installed commands.  If the GOBIN environment variable is
 | 
						|
set, commands are installed to the directory it names instead
 | 
						|
of DIR/bin. GOBIN must be an absolute path.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
Here's an example directory layout:
 | 
						|
</p>
 | 
						|
<pre>GOPATH=/home/user/go
 | 
						|
 | 
						|
/home/user/go/
 | 
						|
    src/
 | 
						|
        foo/
 | 
						|
            bar/               (go code in package bar)
 | 
						|
                x.go
 | 
						|
            quux/              (go code in package main)
 | 
						|
                y.go
 | 
						|
    bin/
 | 
						|
        quux                   (installed command)
 | 
						|
    pkg/
 | 
						|
        linux_amd64/
 | 
						|
            foo/
 | 
						|
                bar.a          (installed package object)
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
Go searches each directory listed in GOPATH to find source code,
 | 
						|
but new packages are always downloaded into the first directory
 | 
						|
in the list.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
See <a href="https://golang.org/doc/code.html">https://golang.org/doc/code.html</a> for an example.
 | 
						|
</p>
 | 
						|
<h3 id="hdr-Internal_Directories">Internal Directories</h3>
 | 
						|
<p>
 | 
						|
Code in or below a directory named "internal" is importable only
 | 
						|
by code in the directory tree rooted at the parent of "internal".
 | 
						|
Here's an extended version of the directory layout above:
 | 
						|
</p>
 | 
						|
<pre>/home/user/go/
 | 
						|
    src/
 | 
						|
        crash/
 | 
						|
            bang/              (go code in package bang)
 | 
						|
                b.go
 | 
						|
        foo/                   (go code in package foo)
 | 
						|
            f.go
 | 
						|
            bar/               (go code in package bar)
 | 
						|
                x.go
 | 
						|
            internal/
 | 
						|
                baz/           (go code in package baz)
 | 
						|
                    z.go
 | 
						|
            quux/              (go code in package main)
 | 
						|
                y.go
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
The code in z.go is imported as "foo/internal/baz", but that
 | 
						|
import statement can only appear in source files in the subtree
 | 
						|
rooted at foo. The source files foo/f.go, foo/bar/x.go, and
 | 
						|
foo/quux/y.go can all import "foo/internal/baz", but the source file
 | 
						|
crash/bang/b.go cannot.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
See <a href="https://golang.org/s/go14internal">https://golang.org/s/go14internal</a> for details.
 | 
						|
</p>
 | 
						|
<h3 id="hdr-Vendor_Directories">Vendor Directories</h3>
 | 
						|
<p>
 | 
						|
Go 1.6 includes support for using local copies of external dependencies
 | 
						|
to satisfy imports of those dependencies, often referred to as vendoring.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
Code below a directory named "vendor" is importable only
 | 
						|
by code in the directory tree rooted at the parent of "vendor",
 | 
						|
and only using an import path that omits the prefix up to and
 | 
						|
including the vendor element.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
Here's the example from the previous section,
 | 
						|
but with the "internal" directory renamed to "vendor"
 | 
						|
and a new foo/vendor/crash/bang directory added:
 | 
						|
</p>
 | 
						|
<pre>/home/user/go/
 | 
						|
    src/
 | 
						|
        crash/
 | 
						|
            bang/              (go code in package bang)
 | 
						|
                b.go
 | 
						|
        foo/                   (go code in package foo)
 | 
						|
            f.go
 | 
						|
            bar/               (go code in package bar)
 | 
						|
                x.go
 | 
						|
            vendor/
 | 
						|
                crash/
 | 
						|
                    bang/      (go code in package bang)
 | 
						|
                        b.go
 | 
						|
                baz/           (go code in package baz)
 | 
						|
                    z.go
 | 
						|
            quux/              (go code in package main)
 | 
						|
                y.go
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
The same visibility rules apply as for internal, but the code
 | 
						|
in z.go is imported as "baz", not as "foo/vendor/baz".
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
Code in vendor directories deeper in the source tree shadows
 | 
						|
code in higher directories. Within the subtree rooted at foo, an import
 | 
						|
of "crash/bang" resolves to "foo/vendor/crash/bang", not the
 | 
						|
top-level "crash/bang".
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
Code in vendor directories is not subject to import path
 | 
						|
checking (see 'go help importpath').
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
When 'go get' checks out or updates a git repository, it now also
 | 
						|
updates submodules.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
Vendor directories do not affect the placement of new repositories
 | 
						|
being checked out for the first time by 'go get': those are always
 | 
						|
placed in the main GOPATH, never in a vendor subtree.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
See <a href="https://golang.org/s/go15vendor">https://golang.org/s/go15vendor</a> for details.
 | 
						|
</p>
 | 
						|
<h3 id="hdr-Environment_variables">Environment variables</h3>
 | 
						|
<p>
 | 
						|
The go command, and the tools it invokes, examine a few different
 | 
						|
environment variables. For many of these, you can see the default
 | 
						|
value of on your system by running 'go env NAME', where NAME is the
 | 
						|
name of the variable.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
General-purpose environment variables:
 | 
						|
</p>
 | 
						|
<pre>GCCGO
 | 
						|
	The gccgo command to run for 'go build -compiler=gccgo'.
 | 
						|
GOARCH
 | 
						|
	The architecture, or processor, for which to compile code.
 | 
						|
	Examples are amd64, 386, arm, ppc64.
 | 
						|
GOBIN
 | 
						|
	The directory where 'go install' will install a command.
 | 
						|
GOOS
 | 
						|
	The operating system for which to compile code.
 | 
						|
	Examples are linux, darwin, windows, netbsd.
 | 
						|
GOPATH
 | 
						|
	For more details see: 'go help gopath'.
 | 
						|
GORACE
 | 
						|
	Options for the race detector.
 | 
						|
	See <a href="https://golang.org/doc/articles/race_detector.html">https://golang.org/doc/articles/race_detector.html</a>.
 | 
						|
GOROOT
 | 
						|
	The root of the go tree.
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
Environment variables for use with cgo:
 | 
						|
</p>
 | 
						|
<pre>CC
 | 
						|
	The command to use to compile C code.
 | 
						|
CGO_ENABLED
 | 
						|
	Whether the cgo command is supported.  Either 0 or 1.
 | 
						|
CGO_CFLAGS
 | 
						|
	Flags that cgo will pass to the compiler when compiling
 | 
						|
	C code.
 | 
						|
CGO_CPPFLAGS
 | 
						|
	Flags that cgo will pass to the compiler when compiling
 | 
						|
	C or C++ code.
 | 
						|
CGO_CXXFLAGS
 | 
						|
	Flags that cgo will pass to the compiler when compiling
 | 
						|
	C++ code.
 | 
						|
CGO_FFLAGS
 | 
						|
	Flags that cgo will pass to the compiler when compiling
 | 
						|
	Fortran code.
 | 
						|
CGO_LDFLAGS
 | 
						|
	Flags that cgo will pass to the compiler when linking.
 | 
						|
CXX
 | 
						|
	The command to use to compile C++ code.
 | 
						|
PKG_CONFIG
 | 
						|
	Path to pkg-config tool.
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
Architecture-specific environment variables:
 | 
						|
</p>
 | 
						|
<pre>GOARM
 | 
						|
	For GOARCH=arm, the ARM architecture for which to compile.
 | 
						|
	Valid values are 5, 6, 7.
 | 
						|
GO386
 | 
						|
	For GOARCH=386, the floating point instruction set.
 | 
						|
	Valid values are 387, sse2.
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
Special-purpose environment variables:
 | 
						|
</p>
 | 
						|
<pre>GOROOT_FINAL
 | 
						|
	The root of the installed Go tree, when it is
 | 
						|
	installed in a location other than where it is built.
 | 
						|
	File names in stack traces are rewritten from GOROOT to
 | 
						|
	GOROOT_FINAL.
 | 
						|
GO_EXTLINK_ENABLED
 | 
						|
	Whether the linker should use external linking mode
 | 
						|
	when using -linkmode=auto with code that uses cgo.
 | 
						|
	Set to 0 to disable external linking mode, 1 to enable it.
 | 
						|
GIT_ALLOW_PROTOCOL
 | 
						|
	Defined by Git. A colon-separated list of schemes that are allowed to be used
 | 
						|
	with git fetch/clone. If set, any scheme not explicitly mentioned will be
 | 
						|
	considered insecure by 'go get'.
 | 
						|
</pre>
 | 
						|
<h3 id="hdr-Import_path_syntax">Import path syntax</h3>
 | 
						|
<p>
 | 
						|
An import path (see 'go help packages') denotes a package stored in the local
 | 
						|
file system.  In general, an import path denotes either a standard package (such
 | 
						|
as "unicode/utf8") or a package found in one of the work spaces (For more
 | 
						|
details see: 'go help gopath').
 | 
						|
</p>
 | 
						|
<h3 id="hdr-Relative_import_paths">Relative import paths</h3>
 | 
						|
<p>
 | 
						|
An import path beginning with ./ or ../ is called a relative path.
 | 
						|
The toolchain supports relative import paths as a shortcut in two ways.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
First, a relative path can be used as a shorthand on the command line.
 | 
						|
If you are working in the directory containing the code imported as
 | 
						|
"unicode" and want to run the tests for "unicode/utf8", you can type
 | 
						|
"go test ./utf8" instead of needing to specify the full path.
 | 
						|
Similarly, in the reverse situation, "go test .." will test "unicode" from
 | 
						|
the "unicode/utf8" directory. Relative patterns are also allowed, like
 | 
						|
"go test ./..." to test all subdirectories. See 'go help packages' for details
 | 
						|
on the pattern syntax.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
Second, if you are compiling a Go program not in a work space,
 | 
						|
you can use a relative path in an import statement in that program
 | 
						|
to refer to nearby code also not in a work space.
 | 
						|
This makes it easy to experiment with small multipackage programs
 | 
						|
outside of the usual work spaces, but such programs cannot be
 | 
						|
installed with "go install" (there is no work space in which to install them),
 | 
						|
so they are rebuilt from scratch each time they are built.
 | 
						|
To avoid ambiguity, Go programs cannot use relative import paths
 | 
						|
within a work space.
 | 
						|
</p>
 | 
						|
<h3 id="hdr-Remote_import_paths">Remote import paths</h3>
 | 
						|
<p>
 | 
						|
Certain import paths also
 | 
						|
describe how to obtain the source code for the package using
 | 
						|
a revision control system.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
A few common code hosting sites have special syntax:
 | 
						|
</p>
 | 
						|
<pre>Bitbucket (Git, Mercurial)
 | 
						|
 | 
						|
	import "bitbucket.org/user/project"
 | 
						|
	import "bitbucket.org/user/project/sub/directory"
 | 
						|
 | 
						|
GitHub (Git)
 | 
						|
 | 
						|
	import "github.com/user/project"
 | 
						|
	import "github.com/user/project/sub/directory"
 | 
						|
 | 
						|
Launchpad (Bazaar)
 | 
						|
 | 
						|
	import "launchpad.net/project"
 | 
						|
	import "launchpad.net/project/series"
 | 
						|
	import "launchpad.net/project/series/sub/directory"
 | 
						|
 | 
						|
	import "launchpad.net/~user/project/branch"
 | 
						|
	import "launchpad.net/~user/project/branch/sub/directory"
 | 
						|
 | 
						|
IBM DevOps Services (Git)
 | 
						|
 | 
						|
	import "hub.jazz.net/git/user/project"
 | 
						|
	import "hub.jazz.net/git/user/project/sub/directory"
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
For code hosted on other servers, import paths may either be qualified
 | 
						|
with the version control type, or the go tool can dynamically fetch
 | 
						|
the import path over https/http and discover where the code resides
 | 
						|
from a <meta> tag in the HTML.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
To declare the code location, an import path of the form
 | 
						|
</p>
 | 
						|
<pre>repository.vcs/path
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
specifies the given repository, with or without the .vcs suffix,
 | 
						|
using the named version control system, and then the path inside
 | 
						|
that repository.  The supported version control systems are:
 | 
						|
</p>
 | 
						|
<pre>Bazaar      .bzr
 | 
						|
Git         .git
 | 
						|
Mercurial   .hg
 | 
						|
Subversion  .svn
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
For example,
 | 
						|
</p>
 | 
						|
<pre>import "example.org/user/foo.hg"
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
denotes the root directory of the Mercurial repository at
 | 
						|
example.org/user/foo or foo.hg, and
 | 
						|
</p>
 | 
						|
<pre>import "example.org/repo.git/foo/bar"
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
denotes the foo/bar directory of the Git repository at
 | 
						|
example.org/repo or repo.git.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
When a version control system supports multiple protocols,
 | 
						|
each is tried in turn when downloading.  For example, a Git
 | 
						|
download tries https://, then git+ssh://.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
By default, downloads are restricted to known secure protocols
 | 
						|
(e.g. https, ssh). To override this setting for Git downloads, the
 | 
						|
GIT_ALLOW_PROTOCOL environment variable can be set (For more details see:
 | 
						|
'go help environment').
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
If the import path is not a known code hosting site and also lacks a
 | 
						|
version control qualifier, the go tool attempts to fetch the import
 | 
						|
over https/http and looks for a <meta> tag in the document's HTML
 | 
						|
<head>.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
The meta tag has the form:
 | 
						|
</p>
 | 
						|
<pre><meta name="go-import" content="import-prefix vcs repo-root">
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
The import-prefix is the import path corresponding to the repository
 | 
						|
root. It must be a prefix or an exact match of the package being
 | 
						|
fetched with "go get". If it's not an exact match, another http
 | 
						|
request is made at the prefix to verify the <meta> tags match.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
The meta tag should appear as early in the file as possible.
 | 
						|
In particular, it should appear before any raw JavaScript or CSS,
 | 
						|
to avoid confusing the go command's restricted parser.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
The vcs is one of "git", "hg", "svn", etc,
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
The repo-root is the root of the version control system
 | 
						|
containing a scheme and not containing a .vcs qualifier.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
For example,
 | 
						|
</p>
 | 
						|
<pre>import "example.org/pkg/foo"
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
will result in the following requests:
 | 
						|
</p>
 | 
						|
<pre><a href="https://example.org/pkg/foo?go-get=1">https://example.org/pkg/foo?go-get=1</a> (preferred)
 | 
						|
<a href="http://example.org/pkg/foo?go-get=1">http://example.org/pkg/foo?go-get=1</a>  (fallback, only with -insecure)
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
If that page contains the meta tag
 | 
						|
</p>
 | 
						|
<pre><meta name="go-import" content="example.org git <a href="https://code.org/r/p/exproj">https://code.org/r/p/exproj</a>">
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
the go tool will verify that <a href="https://example.org/?go-get=1">https://example.org/?go-get=1</a> contains the
 | 
						|
same meta tag and then git clone <a href="https://code.org/r/p/exproj">https://code.org/r/p/exproj</a> into
 | 
						|
GOPATH/src/example.org.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
New downloaded packages are written to the first directory listed in the GOPATH
 | 
						|
environment variable (For more details see: 'go help gopath').
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
The go command attempts to download the version of the
 | 
						|
package appropriate for the Go release being used.
 | 
						|
Run 'go help get' for more.
 | 
						|
</p>
 | 
						|
<h3 id="hdr-Import_path_checking">Import path checking</h3>
 | 
						|
<p>
 | 
						|
When the custom import path feature described above redirects to a
 | 
						|
known code hosting site, each of the resulting packages has two possible
 | 
						|
import paths, using the custom domain or the known hosting site.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
A package statement is said to have an "import comment" if it is immediately
 | 
						|
followed (before the next newline) by a comment of one of these two forms:
 | 
						|
</p>
 | 
						|
<pre>package math // import "path"
 | 
						|
package math /* import "path" */
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
The go command will refuse to install a package with an import comment
 | 
						|
unless it is being referred to by that import path. In this way, import comments
 | 
						|
let package authors make sure the custom import path is used and not a
 | 
						|
direct path to the underlying code hosting site.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
Import path checking is disabled for code found within vendor trees.
 | 
						|
This makes it possible to copy code into alternate locations in vendor trees
 | 
						|
without needing to update import comments.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
See <a href="https://golang.org/s/go14customimport">https://golang.org/s/go14customimport</a> for details.
 | 
						|
</p>
 | 
						|
<h3 id="hdr-Description_of_package_lists">Description of package lists</h3>
 | 
						|
<p>
 | 
						|
Many commands apply to a set of packages:
 | 
						|
</p>
 | 
						|
<pre>go action [packages]
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
Usually, [packages] is a list of import paths.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
An import path that is a rooted path or that begins with
 | 
						|
a . or .. element is interpreted as a file system path and
 | 
						|
denotes the package in that directory.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
Otherwise, the import path P denotes the package found in
 | 
						|
the directory DIR/src/P for some DIR listed in the GOPATH
 | 
						|
environment variable (For more details see: 'go help gopath').
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
If no import paths are given, the action applies to the
 | 
						|
package in the current directory.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
There are four reserved names for paths that should not be used
 | 
						|
for packages to be built with the go tool:
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
- "main" denotes the top-level package in a stand-alone executable.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
- "all" expands to all package directories found in all the GOPATH
 | 
						|
trees. For example, 'go list all' lists all the packages on the local
 | 
						|
system.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
- "std" is like all but expands to just the packages in the standard
 | 
						|
Go library.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
- "cmd" expands to the Go repository's commands and their
 | 
						|
internal libraries.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
Import paths beginning with "cmd/" only match source code in
 | 
						|
the Go repository.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
An import path is a pattern if it includes one or more "..." wildcards,
 | 
						|
each of which can match any string, including the empty string and
 | 
						|
strings containing slashes.  Such a pattern expands to all package
 | 
						|
directories found in the GOPATH trees with names matching the
 | 
						|
patterns.  As a special case, x/... matches x as well as x's subdirectories.
 | 
						|
For example, net/... expands to net and packages in its subdirectories.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
An import path can also name a package to be downloaded from
 | 
						|
a remote repository.  Run 'go help importpath' for details.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
Every package in a program must have a unique import path.
 | 
						|
By convention, this is arranged by starting each path with a
 | 
						|
unique prefix that belongs to you.  For example, paths used
 | 
						|
internally at Google all begin with 'google', and paths
 | 
						|
denoting remote repositories begin with the path to the code,
 | 
						|
such as 'github.com/user/repo'.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
Packages in a program need not have unique package names,
 | 
						|
but there are two reserved package names with special meaning.
 | 
						|
The name main indicates a command, not a library.
 | 
						|
Commands are built into binaries and cannot be imported.
 | 
						|
The name documentation indicates documentation for
 | 
						|
a non-Go program in the directory. Files in package documentation
 | 
						|
are ignored by the go command.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
As a special case, if the package list is a list of .go files from a
 | 
						|
single directory, the command is applied to a single synthesized
 | 
						|
package made up of exactly those files, ignoring any build constraints
 | 
						|
in those files and ignoring any other files in the directory.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
Directory and file names that begin with "." or "_" are ignored
 | 
						|
by the go tool, as are directories named "testdata".
 | 
						|
</p>
 | 
						|
<h3 id="hdr-Description_of_testing_flags">Description of testing flags</h3>
 | 
						|
<p>
 | 
						|
The 'go test' command takes both flags that apply to 'go test' itself
 | 
						|
and flags that apply to the resulting test binary.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
Several of the flags control profiling and write an execution profile
 | 
						|
suitable for "go tool pprof"; run "go tool pprof -h" for more
 | 
						|
information.  The --alloc_space, --alloc_objects, and --show_bytes
 | 
						|
options of pprof control how the information is presented.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
The following flags are recognized by the 'go test' command and
 | 
						|
control the execution of any test:
 | 
						|
</p>
 | 
						|
<pre>-bench regexp
 | 
						|
    Run (sub)benchmarks matching a regular expression.
 | 
						|
    The given regular expression is split into smaller ones by
 | 
						|
    top-level '/', where each must match the corresponding part of a
 | 
						|
    benchmark's identifier.
 | 
						|
    By default, no benchmarks run. To run all benchmarks,
 | 
						|
    use '-bench .' or '-bench=.'.
 | 
						|
 | 
						|
-benchtime t
 | 
						|
    Run enough iterations of each benchmark to take t, specified
 | 
						|
    as a time.Duration (for example, -benchtime 1h30s).
 | 
						|
    The default is 1 second (1s).
 | 
						|
 | 
						|
-count n
 | 
						|
    Run each test and benchmark n times (default 1).
 | 
						|
    If -cpu is set, run n times for each GOMAXPROCS value.
 | 
						|
    Examples are always run once.
 | 
						|
 | 
						|
-cover
 | 
						|
    Enable coverage analysis.
 | 
						|
 | 
						|
-covermode set,count,atomic
 | 
						|
    Set the mode for coverage analysis for the package[s]
 | 
						|
    being tested. The default is "set" unless -race is enabled,
 | 
						|
    in which case it is "atomic".
 | 
						|
    The values:
 | 
						|
	set: bool: does this statement run?
 | 
						|
	count: int: how many times does this statement run?
 | 
						|
	atomic: int: count, but correct in multithreaded tests;
 | 
						|
		significantly more expensive.
 | 
						|
    Sets -cover.
 | 
						|
 | 
						|
-coverpkg pkg1,pkg2,pkg3
 | 
						|
    Apply coverage analysis in each test to the given list of packages.
 | 
						|
    The default is for each test to analyze only the package being tested.
 | 
						|
    Packages are specified as import paths.
 | 
						|
    Sets -cover.
 | 
						|
 | 
						|
-cpu 1,2,4
 | 
						|
    Specify a list of GOMAXPROCS values for which the tests or
 | 
						|
    benchmarks should be executed.  The default is the current value
 | 
						|
    of GOMAXPROCS.
 | 
						|
 | 
						|
-parallel n
 | 
						|
    Allow parallel execution of test functions that call t.Parallel.
 | 
						|
    The value of this flag is the maximum number of tests to run
 | 
						|
    simultaneously; by default, it is set to the value of GOMAXPROCS.
 | 
						|
    Note that -parallel only applies within a single test binary.
 | 
						|
    The 'go test' command may run tests for different packages
 | 
						|
    in parallel as well, according to the setting of the -p flag
 | 
						|
    (see 'go help build').
 | 
						|
 | 
						|
-run regexp
 | 
						|
    Run only those tests and examples matching the regular expression.
 | 
						|
    For tests the regular expression is split into smaller ones by
 | 
						|
    top-level '/', where each must match the corresponding part of a
 | 
						|
    test's identifier.
 | 
						|
 | 
						|
-short
 | 
						|
    Tell long-running tests to shorten their run time.
 | 
						|
    It is off by default but set during all.bash so that installing
 | 
						|
    the Go tree can run a sanity check but not spend time running
 | 
						|
    exhaustive tests.
 | 
						|
 | 
						|
-timeout t
 | 
						|
    If a test runs longer than t, panic.
 | 
						|
    The default is 10 minutes (10m).
 | 
						|
 | 
						|
-v
 | 
						|
    Verbose output: log all tests as they are run. Also print all
 | 
						|
    text from Log and Logf calls even if the test succeeds.
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
The following flags are also recognized by 'go test' and can be used to
 | 
						|
profile the tests during execution:
 | 
						|
</p>
 | 
						|
<pre>-benchmem
 | 
						|
    Print memory allocation statistics for benchmarks.
 | 
						|
 | 
						|
-blockprofile block.out
 | 
						|
    Write a goroutine blocking profile to the specified file
 | 
						|
    when all tests are complete.
 | 
						|
    Writes test binary as -c would.
 | 
						|
 | 
						|
-blockprofilerate n
 | 
						|
    Control the detail provided in goroutine blocking profiles by
 | 
						|
    calling runtime.SetBlockProfileRate with n.
 | 
						|
    See 'go doc runtime.SetBlockProfileRate'.
 | 
						|
    The profiler aims to sample, on average, one blocking event every
 | 
						|
    n nanoseconds the program spends blocked.  By default,
 | 
						|
    if -test.blockprofile is set without this flag, all blocking events
 | 
						|
    are recorded, equivalent to -test.blockprofilerate=1.
 | 
						|
 | 
						|
-coverprofile cover.out
 | 
						|
    Write a coverage profile to the file after all tests have passed.
 | 
						|
    Sets -cover.
 | 
						|
 | 
						|
-cpuprofile cpu.out
 | 
						|
    Write a CPU profile to the specified file before exiting.
 | 
						|
    Writes test binary as -c would.
 | 
						|
 | 
						|
-memprofile mem.out
 | 
						|
    Write a memory profile to the file after all tests have passed.
 | 
						|
    Writes test binary as -c would.
 | 
						|
 | 
						|
-memprofilerate n
 | 
						|
    Enable more precise (and expensive) memory profiles by setting
 | 
						|
    runtime.MemProfileRate.  See 'go doc runtime.MemProfileRate'.
 | 
						|
    To profile all memory allocations, use -test.memprofilerate=1
 | 
						|
    and pass --alloc_space flag to the pprof tool.
 | 
						|
 | 
						|
-mutexprofile mutex.out
 | 
						|
    Write a mutex contention profile to the specified file
 | 
						|
    when all tests are complete.
 | 
						|
    Writes test binary as -c would.
 | 
						|
 | 
						|
-mutexprofilefraction n
 | 
						|
    Sample 1 in n stack traces of goroutines holding a
 | 
						|
    contended mutex.
 | 
						|
 | 
						|
-outputdir directory
 | 
						|
    Place output files from profiling in the specified directory,
 | 
						|
    by default the directory in which "go test" is running.
 | 
						|
 | 
						|
-trace trace.out
 | 
						|
    Write an execution trace to the specified file before exiting.
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
Each of these flags is also recognized with an optional 'test.' prefix,
 | 
						|
as in -test.v. When invoking the generated test binary (the result of
 | 
						|
'go test -c') directly, however, the prefix is mandatory.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
The 'go test' command rewrites or removes recognized flags,
 | 
						|
as appropriate, both before and after the optional package list,
 | 
						|
before invoking the test binary.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
For instance, the command
 | 
						|
</p>
 | 
						|
<pre>go test -v -myflag testdata -cpuprofile=prof.out -x
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
will compile the test binary and then run it as
 | 
						|
</p>
 | 
						|
<pre>pkg.test -test.v -myflag testdata -test.cpuprofile=prof.out
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
(The -x flag is removed because it applies only to the go command's
 | 
						|
execution, not to the test itself.)
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
The test flags that generate profiles (other than for coverage) also
 | 
						|
leave the test binary in pkg.test for use when analyzing the profiles.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
When 'go test' runs a test binary, it does so from within the
 | 
						|
corresponding package's source code directory. Depending on the test,
 | 
						|
it may be necessary to do the same when invoking a generated test
 | 
						|
binary directly.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
The command-line package list, if present, must appear before any
 | 
						|
flag not known to the go test command. Continuing the example above,
 | 
						|
the package list would have to appear before -myflag, but could appear
 | 
						|
on either side of -v.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
To keep an argument for a test binary from being interpreted as a
 | 
						|
known flag or a package name, use -args (see 'go help test') which
 | 
						|
passes the remainder of the command line through to the test binary
 | 
						|
uninterpreted and unaltered.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
For instance, the command
 | 
						|
</p>
 | 
						|
<pre>go test -v -args -x -v
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
will compile the test binary and then run it as
 | 
						|
</p>
 | 
						|
<pre>pkg.test -test.v -x -v
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
Similarly,
 | 
						|
</p>
 | 
						|
<pre>go test -args math
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
will compile the test binary and then run it as
 | 
						|
</p>
 | 
						|
<pre>pkg.test math
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
In the first example, the -x and the second -v are passed through to the
 | 
						|
test binary unchanged and with no effect on the go command itself.
 | 
						|
In the second example, the argument math is passed through to the test
 | 
						|
binary, instead of being interpreted as the package list.
 | 
						|
</p>
 | 
						|
<h3 id="hdr-Description_of_testing_functions">Description of testing functions</h3>
 | 
						|
<p>
 | 
						|
The 'go test' command expects to find test, benchmark, and example functions
 | 
						|
in the "*_test.go" files corresponding to the package under test.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
A test function is one named TestXXX (where XXX is any alphanumeric string
 | 
						|
not starting with a lower case letter) and should have the signature,
 | 
						|
</p>
 | 
						|
<pre>func TestXXX(t *testing.T) { ... }
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
A benchmark function is one named BenchmarkXXX and should have the signature,
 | 
						|
</p>
 | 
						|
<pre>func BenchmarkXXX(b *testing.B) { ... }
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
An example function is similar to a test function but, instead of using
 | 
						|
*testing.T to report success or failure, prints output to os.Stdout.
 | 
						|
If the last comment in the function starts with "Output:" then the output
 | 
						|
is compared exactly against the comment (see examples below). If the last
 | 
						|
comment begins with "Unordered output:" then the output is compared to the
 | 
						|
comment, however the order of the lines is ignored. An example with no such
 | 
						|
comment is compiled but not executed. An example with no text after
 | 
						|
"Output:" is compiled, executed, and expected to produce no output.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
Godoc displays the body of ExampleXXX to demonstrate the use
 | 
						|
of the function, constant, or variable XXX.  An example of a method M with
 | 
						|
receiver type T or *T is named ExampleT_M.  There may be multiple examples
 | 
						|
for a given function, constant, or variable, distinguished by a trailing _xxx,
 | 
						|
where xxx is a suffix not beginning with an upper case letter.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
Here is an example of an example:
 | 
						|
</p>
 | 
						|
<pre>func ExamplePrintln() {
 | 
						|
	Println("The output of\nthis example.")
 | 
						|
	// Output: The output of
 | 
						|
	// this example.
 | 
						|
}
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
Here is another example where the ordering of the output is ignored:
 | 
						|
</p>
 | 
						|
<pre>func ExamplePerm() {
 | 
						|
	for _, value := range Perm(4) {
 | 
						|
		fmt.Println(value)
 | 
						|
	}
 | 
						|
 | 
						|
	// Unordered output: 4
 | 
						|
	// 2
 | 
						|
	// 1
 | 
						|
	// 3
 | 
						|
	// 0
 | 
						|
}
 | 
						|
</pre>
 | 
						|
<p>
 | 
						|
The entire test file is presented as the example when it contains a single
 | 
						|
example function, at least one other function, type, variable, or constant
 | 
						|
declaration, and no test or benchmark functions.
 | 
						|
</p>
 | 
						|
<p>
 | 
						|
See the documentation of the testing package for more information.
 | 
						|
</p>
 | 
						|
 | 
						|
<div id="footer">
 | 
						|
Build version go1.8.<br>
 | 
						|
Except as <a href="https://developers.google.com/site-policies#restrictions">noted</a>,
 | 
						|
the content of this page is licensed under the
 | 
						|
Creative Commons Attribution 3.0 License,
 | 
						|
and code is licensed under a <a href="/LICENSE">BSD license</a>.<br>
 | 
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<a href="http://www.google.com/intl/en/policies/privacy/">Privacy Policy</a>
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