mirror of
https://github.com/tailscale/tailscale.git
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157 lines
3.2 KiB
Go
157 lines
3.2 KiB
Go
// Copyright 2012 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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package exec_test
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import (
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"bytes"
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"context"
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"encoding/json"
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"fmt"
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"io"
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"io/ioutil"
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"log"
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"os"
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"os/exec"
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"strings"
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"time"
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)
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func ExampleLookPath() {
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path, err := exec.LookPath("fortune")
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if err != nil {
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log.Fatal("installing fortune is in your future")
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}
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fmt.Printf("fortune is available at %s\n", path)
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}
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func ExampleCommand() {
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cmd := exec.Command("tr", "a-z", "A-Z")
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cmd.Stdin = strings.NewReader("some input")
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var out bytes.Buffer
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cmd.Stdout = &out
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err := cmd.Run()
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if err != nil {
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log.Fatal(err)
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}
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fmt.Printf("in all caps: %q\n", out.String())
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}
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func ExampleCommand_environment() {
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cmd := exec.Command("prog")
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cmd.Env = append(os.Environ(),
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"FOO=duplicate_value", // ignored
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"FOO=actual_value", // this value is used
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)
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if err := cmd.Run(); err != nil {
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log.Fatal(err)
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}
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}
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func ExampleCmd_Output() {
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out, err := exec.Command("date").Output()
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if err != nil {
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log.Fatal(err)
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}
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fmt.Printf("The date is %s\n", out)
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}
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func ExampleCmd_Run() {
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cmd := exec.Command("sleep", "1")
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log.Printf("Running command and waiting for it to finish...")
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err := cmd.Run()
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log.Printf("Command finished with error: %v", err)
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}
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func ExampleCmd_Start() {
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cmd := exec.Command("sleep", "5")
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err := cmd.Start()
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if err != nil {
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log.Fatal(err)
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}
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log.Printf("Waiting for command to finish...")
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err = cmd.Wait()
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log.Printf("Command finished with error: %v", err)
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}
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func ExampleCmd_StdoutPipe() {
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cmd := exec.Command("echo", "-n", `{"Name": "Bob", "Age": 32}`)
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stdout, err := cmd.StdoutPipe()
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if err != nil {
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log.Fatal(err)
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}
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if err := cmd.Start(); err != nil {
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log.Fatal(err)
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}
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var person struct {
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Name string
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Age int
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}
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if err := json.NewDecoder(stdout).Decode(&person); err != nil {
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log.Fatal(err)
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}
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if err := cmd.Wait(); err != nil {
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log.Fatal(err)
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}
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fmt.Printf("%s is %d years old\n", person.Name, person.Age)
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}
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func ExampleCmd_StdinPipe() {
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cmd := exec.Command("cat")
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stdin, err := cmd.StdinPipe()
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if err != nil {
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log.Fatal(err)
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}
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go func() {
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defer stdin.Close()
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io.WriteString(stdin, "values written to stdin are passed to cmd's standard input")
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}()
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out, err := cmd.CombinedOutput()
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if err != nil {
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log.Fatal(err)
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}
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fmt.Printf("%s\n", out)
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}
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func ExampleCmd_StderrPipe() {
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cmd := exec.Command("sh", "-c", "echo stdout; echo 1>&2 stderr")
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stderr, err := cmd.StderrPipe()
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if err != nil {
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log.Fatal(err)
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}
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if err := cmd.Start(); err != nil {
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log.Fatal(err)
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}
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slurp, _ := ioutil.ReadAll(stderr)
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fmt.Printf("%s\n", slurp)
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if err := cmd.Wait(); err != nil {
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log.Fatal(err)
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}
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}
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func ExampleCmd_CombinedOutput() {
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cmd := exec.Command("sh", "-c", "echo stdout; echo 1>&2 stderr")
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stdoutStderr, err := cmd.CombinedOutput()
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if err != nil {
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log.Fatal(err)
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}
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fmt.Printf("%s\n", stdoutStderr)
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}
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func ExampleCommandContext() {
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ctx, cancel := context.WithTimeout(context.Background(), 100*time.Millisecond)
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defer cancel()
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if err := exec.CommandContext(ctx, "sleep", "5").Run(); err != nil {
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// This will fail after 100 milliseconds. The 5 second sleep
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// will be interrupted.
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}
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}
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