问题关于io/ioutil

怎么入门Golang编程？需要学习哪些知识点？这是新手们刚接触编程时常见的问题；下面golang学习网就来给大家整理分享一些知识点，希望能够给初学者一些帮助。本篇文章就来介绍《问题关于io/ioutil》，涉及到，有需要的可以收藏一下

下午好，

我试图用我对 golang 的有限知识来获取进程 id，以下是我想到的：

package main

import (
    "fmt"
    "io/ioutil"
    "log"
    "os"
    "os/exec"
    "strings"
)

func main() {
    cmd := exec.Command("tasklist.exe")
    out, err := cmd.CombinedOutput()
    if err != nil {
        log.Fatal(err)
    }
    f, err := os.Create("data.txt")

    if err != nil {
        log.Fatal(err)
    }

    defer f.Close()

    val := out
    data := []byte(val)

    _, err2 := f.Write(data)

    if err2 != nil {
        log.Fatal(err2)
    }

    val2 := " and red fox\n"
    data2 := []byte(val2)

    var idx int64 = int64(len(data))

    _, err3 := f.WriteAt(data2, idx)

    if err3 != nil {
        log.Fatal(err3)
    }

    fmt.Println("done")
    /* ioutil.ReadFile returns []byte, error */
    explorer, err := ioutil.ReadFile("data.txt")
    /* ... omitted error check..and please add ... */
    /* find index of newline */
    file := string(data)
    line := 0
    /* func Split(s, sep string) []string */
    temp := strings.Split(file, "\n")

    for _, item := range temp {
        fmt.Println("[", line, "]\t", item)
        line++
    }
    fmt.Println(explorer)
}

我的主要问题是我一直遇到同样的问题，ioutil 不允许我在读取文件之前分配值。

有人能帮我吗？

正确答案

我不知道在你原来的例子中什么不起作用，但是几分钟的实验和阅读 docs for tasklist.exe 给了我更好的东西。主要改进是让 tasklist.exe 通过为其提供参数来完成繁重的工作。

package main

import (
    "bytes"
    "encoding/csv"
    "fmt"
    "log"
    "os/exec"
)

func main() {
    // original command:
    // tasklist.exe /nh /fo csv /fi "IMAGENAME eq explorer.exe"
    // /nh = no header
    // /fo csv = format output to csv
    // /fi = filter on query
    //
    // run tasklist.exe /? for more info
    //
    // sample output:
    // "explorer.exe","4860","Console","1","102,240 K"

    // start tasklist with args to do the hard work for us.
    // we want CSV output (easier to parse), and let tasklist search for explorer.exe.
    // obviously you could seach for another task name instead of explorer.exe.
    //
    // the key thing here is that the query ("IMAGENAME ...") doesn't
    // require " when passed as an arg because exec.Command()
    // will apparently handle that for you 
    // (quoting like `"IMAGENAME..."` produced an error from Output() )
    cmd := exec.Command("tasklist.exe", "/nh", "/fo", "csv", "/fi", "IMAGENAME eq explorer.exe")
    out, err := cmd.Output()
    if err != nil {
        log.Fatalln(err)
    }

    // create a csv reader around the output of the above command.
    // then use ReadAll() to split the csv into [][]string.. a slice
    // of "lines" (aka records, rows) where each line is a slice of 
    // csv "columns" (aka fields, entries).
    r := csv.NewReader(bytes.NewReader(out))
    lines, err := r.ReadAll()
    if err != nil {
        log.Fatalln(err)
    }

    // the result may have multiple processes (eg svchost.exe) or none.
    for _, line := range lines {
        // the process id is at index 1 as a string.
        // do whatever you need to do with the result.
        fmt.Println(line[1])
    }
}

今天关于《问题关于io/ioutil》的内容就介绍到这里了，是不是学起来一目了然！想要了解更多关于的内容请关注golang学习网公众号！