first working nonblocking read stdio & stderr example
Signed-off-by: Jeff Carr <jcarr@wit.com>
This commit is contained in:
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58ab22c55f
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2929260ed6
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@ -1,40 +1,18 @@
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package main
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import "fmt"
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import "log"
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import "strings"
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import "io"
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import "time"
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import "os"
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import "os/exec"
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import "bufio"
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import "reflect"
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import "github.com/davecgh/go-spew/spew"
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import "log"
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/*
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func exampleCommand(a string, b ...string) {
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// cmd := exec.Command(range myargs)
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// args := []string{"/tmp", "/"}
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// cmd := exec.Command(args)
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cmd := exec.Command(a, b...)
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cmd.Stdin = strings.NewReader("foobar")
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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.Println(out.String())
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// fmt.Printf("in all caps: %q\n", out.String())
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}
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// import "io"
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// import "fmt"
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// import "reflect"
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// import "github.com/davecgh/go-spew/spew"
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func format(mybut *ui.Button) {
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log.Println("doButton() mybut =", reflect.ValueOf(mybut).Elem())
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log.Println("format and mount here")
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exampleCommand("ls", "/tmp")
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ping()
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}
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*/
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import "github.com/svent/go-nbreader"
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func ping(hostname string, count int) {
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cmdName := "ping " + hostname
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@ -42,256 +20,38 @@ func ping(hostname string, count int) {
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cmd := exec.Command(cmdArgs[0], cmdArgs[1:len(cmdArgs)]...)
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stdout, _ := cmd.StdoutPipe()
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stderr, _ := cmd.StderrPipe()
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cmd.Start()
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f := bufio.NewWriter(os.Stdout)
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newreader := bufio.NewReader(stdout)
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nbr := nbreader.NewNBReader(newreader, 1024)
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newerrreader := bufio.NewReader(stderr)
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nbrerr := nbreader.NewNBReader(newerrreader, 1024)
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for {
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const delay = 1000 * time.Millisecond
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time.Sleep(delay / 2)
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time.Sleep(2 * time.Millisecond) // only check the buffer 500 times a second
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// log.Println("sleep done")
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oneByte := make([]byte, 100)
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stuff, err := stdout.Read(oneByte)
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if stuff != 0 {
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// log.Println("stuff:", stuff)
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// f.Write([]byte("test \n"))
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f.Write(oneByte)
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f.Flush()
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oneByte := make([]byte, 10)
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count, err := nbr.Read(oneByte)
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if (err != nil) {
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log.Println("Read() count = ", count, "err = ", err)
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}
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if err != nil {
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log.Println("ERROR:", err.Error())
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f.Write([]byte(string(oneByte)))
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f.Flush()
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oneByte = make([]byte, 10)
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count, err = nbrerr.Read(oneByte)
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if (err != nil) {
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log.Println("Read() count = ", count, "err = ", err)
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}
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}
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cmd.Wait()
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}
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// this runs a process, then captures both the stdout
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// and stderr in raw byte (so ncurses-like things work)
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// the does unbuffered writes to stdout by running
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// a flush() on each write to stdout
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func shellRAW(hostname string, count int) {
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cmdName := "ping " + hostname
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cmdArgs := strings.Fields(cmdName)
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cmd := exec.Command(cmdArgs[0], cmdArgs[1:len(cmdArgs)]...)
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// merge stdout and stderr into a combined buffer
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stdout, _ := cmd.StdoutPipe()
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stderr, _ := cmd.StderrPipe()
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merged := io.MultiReader(stderr, stdout)
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scanner := bufio.NewScanner(merged)
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cmd.Start()
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// oneByte := make([]byte, 100)
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num := 1
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for {
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// stuff := scanner.Bytes()
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stuff := scanner.Text()
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if stuff == "" {
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// log.Println("START ", stuff)
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// fmt.Printf(err.Error())
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/*
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f := bufio.NewWriter(os.Stdout)
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f.Write(stuff)
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f.Flush()
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*/
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// break
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} else {
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log.Println("START is nil", stuff)
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}
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/*
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r := bufio.NewReader(stdout)
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line, _, _ := r.ReadLine()
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fmt.Println(string(line))
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*/
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num = num + 1
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/*
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if num > count {
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os.Exit(0)
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}
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*/
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}
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cmd.Wait()
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}
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func script(cmds string) int {
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// split on new lines (while we are at it, handle stupid windows text files
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lines := strings.Split(strings.Replace(cmds, "\r\n", "\n", -1), "\n")
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for _, line := range lines {
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line = strings.TrimSpace(line) // this is like 'chomp' in perl
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fmt.Println("LINE:", line)
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time.Sleep(1)
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// simpleProcess("ls /")
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simpleProcess(line)
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}
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return 0
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}
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// Spawns a process and captures stdout and stderr
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// this has to internally handle 'cd' and call os.Chdir()
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func simpleProcess(cmd string) int {
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log.Println("START " + cmd)
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// cmd := exec.Command("ls", "/tmp", "/ballon", "/")
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cmd = strings.TrimSpace(cmd) // this is like 'chomp' in perl
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cmdArgs := strings.Fields(cmd)
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if (len(cmdArgs) == 0) {
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log.Println("END " + cmd)
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return 0 // nothing to do
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}
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if (cmdArgs[0] == "cd") {
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if (len(cmdArgs) > 1) {
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log.Println("os.Chdir()", cmd)
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os.Chdir(cmdArgs[1])
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}
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log.Println("END " + cmd)
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return 0 // nothing to do
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}
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process := exec.Command(cmdArgs[0], cmdArgs[1:len(cmdArgs)]...)
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stdout, _ := process.StdoutPipe()
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stderr, _ := process.StderrPipe()
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process.Start()
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pid := process.Process.Pid
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log.Println("pid =", pid)
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log.Println(reflect.ValueOf(process.Process).Elem())
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log.Println(reflect.TypeOf(process.Process))
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merged := io.MultiReader(stderr, stdout)
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scanner := bufio.NewScanner(merged)
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for scanner.Scan() {
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line := scanner.Text()
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fmt.Println("NOT " + line) // Println will add back the final '\n'
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}
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if err := scanner.Err(); err != nil {
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// fmt.Fprintln(os.Stderr, "reading standard input:", err)
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fmt.Println("reading standard input:", err)
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}
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// One must wait for the process to formally finish and flush all buffer output
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err := process.Wait()
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// try to process the return value from the OS. As of golang 1.12,
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// this should be cross platform (linux,macos,windows)
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if err != nil {
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spew.Dump(err.(*exec.ExitError))
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spew.Dump(process.ProcessState)
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stuff := err.(*exec.ExitError)
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log.Println("ERROR ", stuff)
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log.Println("END ", cmd)
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return -1
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}
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log.Println("END " + cmd)
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return 0
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}
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func exampleScanner() {
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// cmd := exec.Command("ls", "/tmp", "/ballon", "/")
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cmd := exec.Command("ls", "/ballon")
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stdout, _ := cmd.StdoutPipe()
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cmd.Start()
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scanner := bufio.NewScanner(stdout)
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for scanner.Scan() {
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line := scanner.Text()
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fmt.Println("NOT " + line) // Println will add back the final '\n'
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}
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if err := scanner.Err(); err != nil {
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// fmt.Fprintln(os.Stderr, "reading standard input:", err)
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fmt.Println("reading standard input:", err)
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}
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}
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// prompt = whatever you would type at the command line "ls /tmp"
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// timeout = number of lines to read in until exit
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func stdoutExec(prompt string, timeout int) {
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cmdArgs := strings.Fields(prompt)
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cmd := exec.Command(cmdArgs[0], cmdArgs[1:len(cmdArgs)]...)
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stdout, _ := cmd.StdoutPipe()
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cmd.Start()
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// oneByte := make([]byte, 100)
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num := 1
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for {
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/*
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_, err := stdout.Read(oneByte)
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if err != nil {
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fmt.Printf(err.Error())
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break
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}
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*/
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r := bufio.NewReader(stdout)
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line, _, _ := r.ReadLine()
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fmt.Println(string(line))
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num = num + 1
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if num > timeout {
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os.Exit(0)
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}
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}
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cmd.Wait()
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}
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func brokenping(hostname string, count int) {
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cmdName := "ping " + hostname
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cmdArgs := strings.Fields(cmdName)
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cmd := exec.Command(cmdArgs[0], cmdArgs[1:len(cmdArgs)]...)
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stdout, _ := cmd.StdoutPipe()
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/*
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stderr, _ := cmd.StderrPipe()
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merged := io.MultiReader(stderr, stdout)
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scanner := bufio.NewScanner(merged)
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*/
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scanner := bufio.NewScanner(stdout)
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cmd.Start()
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f := bufio.NewWriter(os.Stdout)
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for {
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time.Sleep(100 * time.Millisecond) // only check the buffer 10 times a second
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log.Println("sleep done")
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smallbuf := make([]byte, 1024) // make a 1K buffer. just do this each time so it's empty
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// stuff, err := stdout.Read(smallbuf)
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smallbuf = scanner.Bytes()
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if len(smallbuf) != 0 {
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log.Println("stuff:", smallbuf)
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// f.Write([]byte("test \n"))
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f.Write(smallbuf)
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f.Flush()
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}
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/*
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if err != nil {
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log.Println("ERROR:", err.Error())
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}
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*/
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/*
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smallbuf = make([]byte, 1024) // make a 1K buffer. just do this each time so it's empty
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log.Println("try stderr")
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stuff, err = stderr.Read(smallbuf)
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log.Println("tried stderr")
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if stuff != 0 {
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log.Println("stuff:", stuff)
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f.Write([]byte("test \n"))
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f.Write(smallbuf)
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f.Flush()
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}
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if err != nil {
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log.Println("ERROR:", err.Error())
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}
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*/
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f.Write([]byte(string(oneByte)))
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f.Flush()
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}
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cmd.Wait()
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