英文:
Goland reading liner per line output of a command
问题
我想逐行读取输出命令。为此，我使用了StdoutPipe方法和bufio库：
package mainimport ("encoding/json""fmt""log""os/exec""bufio")func main() {cmd := exec.Command("printf", "{\"Name\": \"Bob\", \"Age\": 1}\n%.0s", "{1..5}")stdout, err := cmd.StdoutPipe()if err != nil {log.Fatal(err)}scanner := bufio.NewScanner(stdout)if err := cmd.Start(); err != nil {log.Fatal(err)}var person struct {Name stringAge int}for scanner.Scan() {if err := json.Unmarshal([]byte(scanner.Text()), &person); err != nil {log.Fatal(err)} else {fmt.Printf("%s is %d years old\n", person.Name, person.Age)}}if err := cmd.Wait(); err != nil {log.Fatal(err)}}
我应该得到5行输出：
$ printf "{\"Name\": \"Bob\", \"Age\": 1}\n%.0s" {1..5}{"Name": "Bob", "Age": 1}{"Name": "Bob", "Age": 1}{"Name": "Bob", "Age": 1}{"Name": "Bob", "Age": 1}{"Name": "Bob", "Age": 1}
问题在于我只得到了第一行。我对Go不太熟悉，我猜测StdoutPipe的使用方法不正确。
英文:
I would like to read an output command line per line. For this I use the StdoutPipe method and the bufio library:
package mainimport ("encoding/json""fmt""log""os/exec""bufio")func main() {cmd := exec.Command("printf", "{\"Name\": \"Bob\", \"Age\": 1}\n%.0s", "{1..5}")stdout, err := cmd.StdoutPipe()if err != nil {log.Fatal(err)}scanner := bufio.NewScanner(stdout)if err := cmd.Start(); err != nil {log.Fatal(err)}var person struct {Name stringAge int}for scanner.Scan() {if err := json.Unmarshal([]byte(scanner.Text()), &person); err != nil {log.Fatal(err)} else {fmt.Printf("%s is %d years old\n", person.Name, person.Age)}}if err := cmd.Wait(); err != nil {log.Fatal(err)}}
I should obtain 5 lines:
$ printf "{\"Name\": \"Bob\", \"Age\": 1}\n%.0s" {1..5}{"Name": "Bob", "Age": 1}{"Name": "Bob", "Age": 1}{"Name": "Bob", "Age": 1}{"Name": "Bob", "Age": 1}{"Name": "Bob", "Age": 1}
The point is that I only get the first line. I am quite new on Goand I guess the usage of the StdoutPipe is incorrect.
答案1
得分: 1
{1..5}在shell中被展开为1 2 3 4 5，所以你必须自己完成这个操作：
cmd := exec.Command("printf", `{"Name": "Bob", "Age": %s}\n`, `1`, `2`) // 等等。
另外请注意使用原始字符串，它比不断转义所有内容更方便。另外，与此相关的是，你应该真正使用scanner.Bytes()而不是[]byte(scanner.Text())。
英文:
{1..5} is expanded to 1 2 3 4 5 by the shell, so you must do it yourself:
cmd := exec.Command("printf", `{"Name": "Bob", "Age": %s}\n`, `1`, `2`) // etc.
Also note the use of raw strings, its much more convenient than constantly escaping everything. And on a related note, instead of []byte(scanner.Text()) you should really use scanner.Bytes().
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