go
Go is a tool for managing Go source code.

Usage:

	go <command> [arguments]

The commands are:

	bug         start a bug report
	build       compile packages and dependencies
	clean       remove object files and cached files
	doc         show documentation for package or symbol
	env         print Go environment information
	fix         update packages to use new APIs
	fmt         gofmt (reformat) package sources
	generate    generate Go files by processing source
	get         add dependencies to current module and install them
	install     compile and install packages and dependencies
	list        list packages or modules
	mod         module maintenance
	run         compile and run Go program
	test        test packages
	tool        run specified go tool
	version     print Go version
	vet         report likely mistakes in packages

Use "go help <command>" for more information about a command.

Additional help topics:

	buildmode   build modes
	c           calling between Go and C
	cache       build and test caching
	environment environment variables
	filetype    file types
	go.mod      the go.mod file
	gopath      GOPATH environment variable
	gopath-get  legacy GOPATH go get
	goproxy     module proxy protocol
	importpath  import path syntax
	modules     modules, module versions, and more
	module-get  module-aware go get
	module-auth module authentication using go.sum
	module-private module configuration for non-public modules
	packages    package lists and patterns
	testflag    testing flags
	testfunc    testing functions

Use "go help <topic>" for more information about that topic.

go env
GOARCH="amd64"
GOBIN=""
GOCACHE="/root/.cache/go-build"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/root/xxxx"
GOPROXY=""
GORACE=""
GOROOT="/usr/lib/golang"
GOTMPDIR=""
GOTOOLDIR="/usr/lib/golang/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build350351294=/tmp/go-build -gno-record-gcc-switches"

go doc go/build
package build // import "go/build"

Package build gathers information about Go packages.


Go Path

The Go path is a list of directory trees containing Go source code. It is
consulted to resolve imports that cannot be found in the standard Go tree.
The default path is the value of the GOPATH environment variable,
interpreted as a path list appropriate to the operating system (on Unix, the
variable is a colon-separated string; on Windows, a semicolon-separated
string; on Plan 9, a list).

Each directory listed in the Go path must have a prescribed structure:

The src/ directory holds source code. The path below 'src' determines the
import path or executable name.

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).

If DIR is a directory listed in the Go path, 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" (or, for gccgo,
"DIR/pkg/gccgo/foo/libbar.a").

The bin/ directory holds compiled commands. Each command is named for its
source directory, but only using 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/ is stripped so that you can add
DIR/bin to your PATH to get at the installed commands.

Here's an example directory layout:

    GOPATH=/home/user/gocode

    /home/user/gocode/
        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)


Build Constraints

A build constraint, also known as a build tag, is a line comment that begins

    // +build

that lists the conditions under which a file should be included in the
package. Constraints may appear in any kind of source file (not just Go),
but they must appear near the top of the file, preceded only by blank lines
and other line comments. These rules mean that in Go files a build
constraint must appear before the package clause.

To distinguish build constraints from package documentation, a series of
build constraints must be followed by a blank line.

A build constraint is evaluated as the OR of space-separated options; each
option evaluates as the AND of its comma-separated terms; and each term is
an alphanumeric word or, preceded by !, its negation. That is, the build
constraint:

    // +build linux,386 darwin,!cgo

corresponds to the boolean formula:

    (linux AND 386) OR (darwin AND (NOT cgo))

A file may have multiple build constraints. The overall constraint is the
AND of the individual constraints. That is, the build constraints:

    // +build linux darwin
    // +build 386

corresponds to the boolean formula:

    (linux OR darwin) AND 386

During a particular build, the following words are satisfied:

    - the target operating system, as spelled by runtime.GOOS
    - the target architecture, as spelled by runtime.GOARCH
    - the compiler being used, either "gc" or "gccgo"
    - "cgo", if ctxt.CgoEnabled is true
    - "go1.1", from Go version 1.1 onward
    - "go1.2", from Go version 1.2 onward
    - "go1.3", from Go version 1.3 onward
    - "go1.4", from Go version 1.4 onward
    - "go1.5", from Go version 1.5 onward
    - "go1.6", from Go version 1.6 onward
    - "go1.7", from Go version 1.7 onward
    - "go1.8", from Go version 1.8 onward
    - "go1.9", from Go version 1.9 onward
    - "go1.10", from Go version 1.10 onward
    - "go1.11", from Go version 1.11 onward
    - any additional words listed in ctxt.BuildTags

If a file's name, after stripping the extension and a possible _test suffix,
matches any of the following patterns:

    *_GOOS
    *_GOARCH
    *_GOOS_GOARCH

(example: source_windows_amd64.go) where GOOS and GOARCH represent any known
operating system and architecture values respectively, then the file is
considered to have an implicit build constraint requiring those terms (in
addition to any explicit constraints in the file).

To keep a file from being considered for the build:

    // +build ignore

(any other unsatisfied word will work as well, but ``ignore'' is
conventional.)

To build a file only when using cgo, and only on Linux and OS X:

    // +build linux,cgo darwin,cgo

Such a file is usually paired with another file implementing the default
functionality for other systems, which in this case would carry the
constraint:

    // +build !linux,!darwin !cgo

Naming a file dns_windows.go will cause it to be included only when building
the package for Windows; similarly, math_386.s will be included only when
building the package for 32-bit x86.

Using GOOS=android matches build tags and files as for GOOS=linux in
addition to android tags and files.


Binary-Only Packages

It is possible to distribute packages in binary form without including the
source code used for compiling the package. To do this, the package must be
distributed with a source file not excluded by build constraints and
containing a "//go:binary-only-package" comment. Like a build constraint,
this comment must appear near the top of the file, preceded only by blank
lines and other line comments and with a blank line following the comment,
to separate it from the package documentation. Unlike build constraints,
this comment is only recognized in non-test Go source files.

The minimal source code for a binary-only package is therefore:

    //go:binary-only-package

    package mypkg

The source code may include additional Go code. That code is never compiled
but will be processed by tools like godoc and might be useful as end-user
documentation.

var ToolDir = getToolDir()
func ArchChar(goarch string) (string, error)
func Import(path, srcDir string, mode ImportMode) (*Package, error)
func ImportDir(dir string, mode ImportMode) (*Package, error)
func IsLocalImport(path string) bool
type Context struct{ ... }
    var Default Context = defaultContext()
type ImportMode uint
    const FindOnly ImportMode = 1 << iota ...
type MultiplePackageError struct{ ... }
type NoGoError struct{ ... }
type Package struct{ ... }

go doc time

go doc time.Since
func Since(t Time) Duration
    Since returns the time elapsed since t. It is shorthand for
    time.Now().Sub(t).

go doc time.Duration.Seconds
func (d Duration) Seconds() float64
    Seconds returns the duration as a floating point number of seconds.

go list github.com/go-sql-driver/mysql
github.com/go-sql-driver/mysql

go list ...mysql...
github.com/go-sql-driver/mysql

go list -f '' strconv
errors internal/cpu math math/bits unicode/utf8 unsafe

 go list -f ' -> ' compress/...

compress/bzip2 -> bufio io sort
compress/flate -> bufio fmt io math math/bits sort strconv sync
compress/gzip -> bufio compress/flate encoding/binary errors fmt hash/crc32 io time
compress/lzw -> bufio errors fmt io
compress/zlib -> bufio compress/flate errors fmt hash hash/adler32 io

.
├── .gitignore
├── README.md
├── cmd
│   ├── kube-proxy
│   │   └── kube-proxy.go
│   └── kubeadm
│       └── kubeadm.go
└── pkg
    ├── proxy
    │   └── xxxx.go

rm -rf vendor
git add -A
git commit -m "remove vendor"
composer update --prefer-dist
git add . -A
git commit -m "recover vendor"

composer update --prefer-dist
git add . -A
git commit -m "recover vendor"