`exec.Command()`在運行`kcat`時不產生任何輸出

我需要封裝kcat一個 Go 函式來讀取一系列的主題訊息，所以想到使用exec.Command()如下：

package main

import (
    "fmt"
    "os/exec"
)

func main() {

    cmd := exec.Command("kcat", "-b kafka.kafka.svc.cluster.local:9092", "-t messages", "-o 11000", "-c 11333")

    fmt.Println("Command String:", cmd.String())

    out, err := cmd.CombinedOutput()

    if err != nil {
        fmt.Println("Error Accessing kafka topic messages ", err.Error(), string(out))
        return
    }

    fmt.Println("Result Length:", len(out))

    fmt.Println("Result Content:", string(out))

}

但是，這僅回傳kcat輸出的第一行：

/app/tools # ./five
Command String: /usr/bin/kcat -b kafka.kafka.svc.cluster.local:9092 -t messages -o 11000 -c 11333
Result Length: 58

Result Content: % Auto-selecting Producer mode (use -P or -C to override)

（注意：我在 docker 容器中運行它，但我認為它沒有區別）

但是，當直接從 CLI 運行時，這可以正常作業：

/app/tools # 
/app/tools # kcat -b kafka.kafka.svc.cluster.local:9092 -t messages -o 10 -c 15
% Auto-selecting Consumer mode (use -P or -C to override)
%4|1640957136.462|OFFSET|rdkafka#consumer-1| [thrd:main]: messages [1]: offset reset (at offset 10) to END: fetch failed due to requested offset not available on the broker: Broker: Offset out of range
%4|1640957136.483|OFFSET|rdkafka#consumer-1| [thrd:main]: messages [2]: offset reset (at offset 10) to END: fetch failed due to requested offset not available on the broker: Broker: Offset out of range
[{"Name":"newOrder", "ID":"9266","Time":"9266","Data":"new order", "Eventname":"newOrder"}]

[{"Name":"newOrder", "ID":"1547","Time":"1547","Data":"new order", "Eventname":"newOrder"}]

[{"Name":"newOrder", "ID":"9179","Time":"9179","Data":"new order", "Eventname":"newOrder"}]

[{"Name":"newOrder", "ID":"8740","Time":"8740","Data":"new order", "Eventname":"newOrder"}]

[{"Name":"newOrder", "ID":"9318","Time":"9318","Data":"new order", "Eventname":"newOrder"}]

[{"Name":"newOrder", "ID":"1743","Time":"1743","Data":"new order", "Eventname":"newOrder"}]

在 Gokcat中中斷的命令似乎有一些獨特之處exec.Command()。

問題：

• 有沒有其他方法可以在 Go 中達到相同的效果？
• 這可能是我使用方式的問題嗎 exec.Command()

理想情況下，我可以kcat在這種情況下使用命令，因為我想避免在這種情況下使用 segmentioskafka-go庫。

[編輯]

• 分隔引數（如@onecricketeer 所建議）：

cmd := exec.Command("kcat", "-b", "kafka.kafka.svc.cluster.local:9092", "-t", "messages", "-o", "11000", "-c", "11333")

結果（同樣的錯誤）：

/app/tools # ./code
Command String: /usr/bin/kcat -b kafka.kafka.svc.cluster.local:9092 -t messages -o 11000 -c 11333
Result Length: 58
Result Content: % Auto-selecting Producer mode (use -P or -C to override)

• Using BASH as the shell (suggested by maxm):

Same result, i.e only the first line of the kcat output is reported:

/app/tools # ./code
Command String: /bin/bash -c kcat -b kafka.kafka.svc.cluster.local:9092 -t messages -o 11000 -c 11333
Result Length: 58
Result Content: % Auto-selecting Producer mode (use -P or -C to override)

[EDIT]

NOTE: However, when I use Python's shell execution mechanism, it works fine, which leads me to wonder if there is something defective about Gos shell handling features:

import subprocess

process = subprocess.Popen(["kcat","-b","kafka.kafka.svc.cluster.local:9092","-t","messages","-o","1", "-c", "11"], 
                           stdout=subprocess.PIPE,
                           universal_newlines=True)

while True:
    output = process.stdout.readline()
    print(output.strip())
    # Do something else
    return_code = process.poll()
    if return_code is not None:
        print('RETURN CODE', return_code)
        # Process has finished, read rest of the output 
        for output in process.stdout.readlines():
            print(output.strip())
        break

Results:

/app/tools/python # python3 code.py 
% Auto-selecting Consumer mode (use -P or -C to override)
%4|1641004616.232|OFFSET|rdkafka#consumer-1| [thrd:main]: messages [2]: offset reset (at offset 1) to END: fetch failed due to requested offset not available on the broker: Broker: Offset out of range
%4|1641004616.236|OFFSET|rdkafka#consumer-1| [thrd:main]: messages [1]: offset reset (at offset 1) to END: fetch failed due to requested offset not available on the broker: Broker: Offset out of range
[{"Name":"newOrder", "ID":"4512","Time":"4512","Data":"new order", "Eventname":"newOrder"}]

RETURN CODE 0
[{"Name":"newOrder", "ID":"2388","Time":"2388","Data":"new order", "Eventname":"newOrder"}]

[{"Name":"newOrder", "ID":"8707","Time":"8707","Data":"new order", "Eventname":"newOrder"}]

[{"Name":"newOrder", "ID":"1643","Time":"1643","Data":"new order", "Eventname":"newOrder"}]

[{"Name":"newOrder", "ID":"2421","Time":"2421","Data":"new order", "Eventname":"newOrder"}]

[{"Name":"newOrder", "ID":"7520","Time":"7520","Data":"new order", "Eventname":"newOrder"}]

[{"Name":"newOrder", "ID":"1258","Time":"1258","Data":"new order", "Eventname":"newOrder"}]

[{"Name":"newOrder", "ID":"1457","Time":"1457","Data":"new order", "Eventname":"newOrder"}]

[{"Name":"newOrder", "ID":"2907","Time":"2907","Data":"new order", "Eventname":"newOrder"}]

[{"Name":"newOrder", "ID":"9266","Time":"9266","Data":"new order", "Eventname":"newOrder"}]

[{"Name":"newOrder", "ID":"1547","Time":"1547","Data":"new order", "Eventname":"newOrder"}]

uj5u.com熱心網友回復：

去命令：

cmd := exec.Command("kcat", "-b kafka.kafka.svc.cluster.local:9092", "-t messages", "-o 11000", "-c 11333")

與shell命令相同：

kcat "-b kafka.kafka.svc.cluster.local:9092" "-t messages" "-o 11000" "-c 11333"

您需要將引數分開，就像 shell 在默認情況下在每個空間上為您所做的一樣：

cmd := exec.Command("kcat", "-b", "kafka.kafka.svc.cluster.local:9092", "-t", "messages", "-o", "11000", "-c", "11333")

uj5u.com熱心網友回復：

正如輸出所說，正在自動選擇生產者模式

嘗試使用帶有分隔引數的消費者模式

cmd := exec.Command("kcat", "-C", "-b", "kafka.kafka.svc.cluster.local:9092", "-t", "messages", "-o", "11000", "-c", "11333")

標籤：docker go kafkacat

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