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// Copyright 2017 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package base defines shared basic pieces of the go command,
// in particular logging and the Command structure.
package base
import (
// A Command is an implementation of a go command
// like go build or go fix.
type Command struct {
// Run runs the command.
// The args are the arguments after the command name.
Run func(cmd *Command, args []string)
// UsageLine is the one-line usage message.
// The words between "go" and the first flag or argument in the line are taken to be the command name.
UsageLine string
// Short is the short description shown in the 'go help' output.
Short string
// Long is the long message shown in the 'go help <this-command>' output.
Long string
// Flag is a set of flags specific to this command.
Flag flag.FlagSet
// CustomFlags indicates that the command will do its own
// flag parsing.
CustomFlags bool
// Commands lists the available commands and help topics.
// The order here is the order in which they are printed by 'go help'.
// Note that subcommands are in general best avoided.
Commands []*Command
var Go = &Command{
UsageLine: "go",
Long: `Go is a tool for managing Go source code.`,
// Commands initialized in package main
// LongName returns the command's long name: all the words in the usage line between "go" and a flag or argument,
func (c *Command) LongName() string {
name := c.UsageLine
if i := strings.Index(name, " ["); i >= 0 {
name = name[:i]
if name == "go" {
return ""
return strings.TrimPrefix(name, "go ")
// Name returns the command's short name: the last word in the usage line before a flag or argument.
func (c *Command) Name() string {
name := c.LongName()
if i := strings.LastIndex(name, " "); i >= 0 {
name = name[i+1:]
return name
func (c *Command) Usage() {
fmt.Fprintf(os.Stderr, "usage: %s\n", c.UsageLine)
fmt.Fprintf(os.Stderr, "Run 'go help %s' for details.\n", c.LongName())
// Runnable reports whether the command can be run; otherwise
// it is a documentation pseudo-command such as importpath.
func (c *Command) Runnable() bool {
return c.Run != nil
var atExitFuncs []func()
func AtExit(f func()) {
atExitFuncs = append(atExitFuncs, f)
func Exit() {
for _, f := range atExitFuncs {
func Fatalf(format string, args ...interface{}) {
Errorf(format, args...)
func Errorf(format string, args ...interface{}) {
log.Printf(format, args...)
func ExitIfErrors() {
if exitStatus != 0 {
var exitStatus = 0
var exitMu sync.Mutex
func SetExitStatus(n int) {
if exitStatus < n {
exitStatus = n
func GetExitStatus() int {
return exitStatus
// Run runs the command, with stdout and stderr
// connected to the go command's own stdout and stderr.
// If the command fails, Run reports the error using Errorf.
func Run(cmdargs ...interface{}) {
cmdline := str.StringList(cmdargs...)
if cfg.BuildN || cfg.BuildX {
fmt.Printf("%s\n", strings.Join(cmdline, " "))
if cfg.BuildN {
cmd := exec.Command(cmdline[0], cmdline[1:]...)
cmd.Stdout = os.Stdout
cmd.Stderr = os.Stderr
if err := cmd.Run(); err != nil {
Errorf("%v", err)
// RunStdin is like run but connects Stdin.
func RunStdin(cmdline []string) {
cmd := exec.Command(cmdline[0], cmdline[1:]...)
cmd.Stdin = os.Stdin
cmd.Stdout = os.Stdout
cmd.Stderr = os.Stderr
cmd.Env = cfg.OrigEnv
if err := cmd.Run(); err != nil {
Errorf("%v", err)
// Usage is the usage-reporting function, filled in by package main
// but here for reference by other packages.
var Usage func()