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打印子进程stdout行输出

subprocess python-3.x python

Floren · 技术社区 · 2 年前

我创建了一个简单的Python函数:

import subprocess
from io import TextIOWrapper


def run_shell_command(command: list, debug: bool = False):
    '''
    Run shell command

    :param command: Shell command
    :param debug: Debug mode
    :return: Result code and message
    '''
    try:
        process = subprocess.run(
            command, check=True, text=True, timeout=5,
            stdout=subprocess.PIPE, stderr=subprocess.STDOUT
        )
        if debug:
            for line in TextIOWrapper(process.stdout, encoding='utf-8'):
                print(line)
        message = 'Shell command executed sucessfully'
        return ({'code': 200, 'msg': message, 'stdout': process.stdout})
    except subprocess.CalledProcessError as e:
        return ({'code': 500, 'msg': e.output})


if __name__ == "__main__":
    command = run_shell_command(['ls', '-lah'], True)
    print(command)

当我在调试模式下运行它时,我得到以下错误:

Traceback (most recent call last):
  File "/tmp/command.py", line 28, in <module>
    command = run_shell_command(['ls', '-lah'], True)
  File "/tmp/command.py", line 19, in run_shell_command
    for line in TextIOWrapper(process.stdout, encoding="utf-8"):
AttributeError: 'str' object has no attribute 'readable'

在Linux服务器上运行Python 3.9,我想知道你是否能提供一些问题所在的见解。在禁用调试的情况下,我得到了一个正确的文本输出。谢谢你的帮助。

编辑:根据下面的评论,修复很简单:

        if debug:
            print(process.stdout.rstrip())

然而,与原始规范相比,国际海事组织接受的解决方案更好。

1 回复 | 直到 2 年前

AKX Bryan Oakley 2 年前

不幸的是,“简单”并不能解决所有涉及的极端情况,您需要阅读子流程 stdout 在流媒体播放时,将其打印出来和将其累积在缓冲区中,并跟踪时间,以便正确超时。请注意,如果4096字节的读取恰好以多行字符结尾,这也可能存在错误(尽管不是很危险)。

def run_shell_command(command: list, debug: bool = False, timeout: float = 5):
    """
    Run shell command

    :param command: Shell command
    :param debug: Debug mode
    :return: Result code and message
    """
    with subprocess.Popen(
        command,
        stdout=subprocess.PIPE,
        stderr=subprocess.STDOUT,
    ) as process:
        start_time = time.time()
        output = b""
        while True:
            buf = process.stdout.read(4096)
            if debug:
                # could fail if `buf` happens to end in a multi-byte character
                print(buf.decode("utf-8", "ignore"))
            output += buf

            if time.time() - start_time > timeout:
                process.kill()
                message = "Shell command timed out"
                return {"code": 500, "msg": message, "stdout": output}

            if process.poll() is not None:
                break
    if process.returncode != 0:
        message = "Shell command failed"
        return {"code": 500, "msg": message, "stdout": output}

    message = "Shell command executed successfully"
    return {"code": 200, "msg": message, "stdout": output}

if __name__ == "__main__":
    command = run_shell_command(["ls", "-lah"], True)
    print(command)