os/exec: add some examples

R=golang-dev, adg, r, bradfitz
CC=golang-dev
https://golang.org/cl/5675054

diff --git a/src/pkg/os/exec/example_test.go b/src/pkg/os/exec/example_test.go
new file mode 100644 (file)
index 0000000..55eaac8
--- /dev/null
+++ b/src/pkg/os/exec/example_test.go
@@ -0,0 +1,75 @@
+// Copyright 2012 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 exec_test
+
+import (
+       "bytes"
+       "encoding/json"
+       "fmt"
+       "log"
+       "os/exec"
+       "strings"
+)
+
+func ExampleLookPath() {
+       path, err := exec.LookPath("fortune")
+       if err != nil {
+               log.Fatal("installing fortune is in your future")
+       }
+       fmt.Printf("fortune is available at %s\n", path)
+}
+
+func ExampleCommand() {
+       cmd := exec.Command("tr", "a-z", "A-Z")
+       cmd.Stdin = strings.NewReader("some input")
+       var out bytes.Buffer
+       cmd.Stdout = &out
+       err := cmd.Run()
+       if err != nil {
+               log.Fatal(err)
+       }
+       fmt.Printf("in all caps: %q\n", out.String())
+}
+
+func ExampleCmd_Output() {
+       out, err := exec.Command("date").Output()
+       if err != nil {
+               log.Fatal(err)
+       }
+       fmt.Printf("The date is %s\n", out)
+}
+
+func ExampleCmd_Start() {
+       cmd := exec.Command("sleep", "5")
+       err := cmd.Start()
+       if err != nil {
+               log.Fatal(err)
+       }
+       log.Printf("Waiting for command to finish...")
+       err = cmd.Wait()
+       log.Printf("Command finished with error: %v", err)
+}
+
+func ExampleCmd_StdoutPipe() {
+       cmd := exec.Command("echo", "-n", `{"Name": "Bob", "Age": 32}`)
+       stdout, err := cmd.StdoutPipe()
+       if err != nil {
+               log.Fatal(err)
+       }
+       if err := cmd.Start(); err != nil {
+               log.Fatal(err)
+       }
+       var person struct {
+               Name string
+               Age  int
+       }
+       if err := json.NewDecoder(stdout).Decode(&person); err != nil {
+               log.Fatal(err)
+       }
+       if err := cmd.Wait(); err != nil {
+               log.Fatal(err)
+       }
+       fmt.Printf("%s is %d years old\n", person.Name, person.Age)
+}