1. 创建临时文件
2. 使用编辑器编辑
3. 获取内容
4. 删除临时文件

package main

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

func main() {
    // create a tmp file
    // ioutil.TempFile creates a temp file and opens the file for reading and writing
    // and returns the resulting *os.File (file descriptor).
    tmpFile, err := ioutil.TempFile(os.TempDir(), "todo-tmp-")
    if err != nil {
        log.Fatal("Cannot create temporary file", err)
    }
    // defer os.Remove(tmpFile.Name())
    defer tmpFile.Close()
    fmt.Println("Created File: " + tmpFile.Name())

    // choose editor by env var
    editor := os.Getenv("EDITOR")
    args := []string{}
    if editor == "" {
        editor = "vim"
        args = append(args, "--clean")
        fmt.Println("No EDITOR enviroment variable set, use " + editor)
    } else {
        fmt.Println("Using EDITOR enviroment variable: " + editor)
    }
    args = append(args, tmpFile.Name())
    fmt.Println("Opening file with " + editor + " with args: " + fmt.Sprint(args))

    // check the editor command is available
    // _, err = exec.LookPath(editor)
    // if err != nil {
    //  log.Fatal("Cannot find editor: " + editor)
    // }

    // call the editor
    cmd := exec.Command(editor, args...)
    cmd.Stdin = os.Stdin
    cmd.Stdout = os.Stdout
    cmd.Stderr = os.Stderr
    err = cmd.Run()
    if err != nil {
        log.Fatal("Cannot run editor: " + editor)
    }

    // read the file
    // data, err := ioutil.ReadFile(tmpFile.Name())
    // if err != nil {
    //  log.Fatal("Cannot read file: " + tmpFile.Name())
    // }
    tmpFile.Seek(0, 0)
    s := bufio.NewScanner(tmpFile)
    for s.Scan() {
        fmt.Println("Content:\n\n" + s.Text())
    }
    if err = s.Err(); err != nil {
        log.Fatal("error reading temp file", err)
    }
}