让 python 等到 subprocess.call 完成它的命令

Question

所以这个问题是 this 的后续问题（阅读评论以及我采取的路径）。我只希望第一个调用 robocopy 在继续执行其余代码之前完成执行。因为我希望第二个 robocopy 跳过所有文件，因为它们已经被复制了。然而，正在发生的事情是脚本的其余部分将运行（即启动第二个 robocopy），而第一个 robocopy 正在复制文件。下面是代码：

call(["start", "cmd", "/K", "RoboCopy.exe", f"{self.srcEntry.get()}", f"{self.dstEntry.get()}", "*.*", "/E", "/Z", "/MT:8"], stdout=PIPE, shell=True) 
temp2 = Popen(["RoboCopy.exe", f"{self.srcEntry.get()}", f"{self.dstEntry.get()}", "*.*", "/E", "/Z"], stdout=PIPE, stdin=PIPE, shell=True)

编辑 1：

复制大文件时问题很明显。我正在考虑加入一个睡眠功能，该功能取决于要复制的文件的总大小。但是，这没有考虑 upload/download 速度，因为文件将通过网络传输。

Answer 1

我使用以下函数启动我的命令，该命令等待操作完成，但有一个超时：

import os
import logging

logger = logging.getLogger()

def command_runner(command, valid_exit_codes=None, timeout=30, shell=False, decoder='utf-8'):
    """
    command_runner 2019103101
    Whenever we can, we need to avoid shell=True in order to preseve better security
    Runs system command, returns exit code and stdout/stderr output, and logs output on error
    valid_exit_codes is a list of codes that don't trigger an error
    """

    try:
        # universal_newlines=True makes netstat command fail under windows
        # timeout does not work under Python 2.7 with subprocess32 < 3.5
        # decoder may be unicode_escape for dos commands or utf-8 for powershell
        if sys.version_info >= (3, 0):
            output = subprocess.check_output(command, stderr=subprocess.STDOUT, shell=shell,
                                             timeout=timeout, universal_newlines=False)
        else:
            output = subprocess.check_output(command, stderr=subprocess.STDOUT, shell=shell,
                                             universal_newlines=False)
        output = output.decode(decoder, errors='backslashreplace')
    except subprocess.CalledProcessError as exc:
        exit_code = exc.returncode
        # noinspection PyBroadException
        try:
            output = exc.output
            try:
                output = output.decode(decoder, errors='backslashreplace')
            except Exception as subexc:
                logger.debug(subexc, exc_info=True)
                logger.debug('Cannot properly decode error. Text is %s' % output)
        except Exception:
            output = "command_runner: Could not obtain output from command."
        if exit_code in valid_exit_codes if valid_exit_codes is not None else [0]:
            logger.debug('Command [%s] returned with exit code [%s]. Command output was:' % (command, exit_code))
            if output:
                logger.debug(output)
            return exc.returncode, output
        else:
            logger.error('Command [%s] failed with exit code [%s]. Command output was:' %
                         (command, exc.returncode))
            logger.error(output)
            return exc.returncode, output
    # OSError if not a valid executable
    except OSError as exc:
        logger.error('Command [%s] faild because of OS [%s].' % (command, exc))
        return None, exc
    except subprocess.TimeoutExpired:
        logger.error('Timeout [%s seconds] expired for command [%s] execution.' % (timeout, command))
        return None, 'Timeout of %s seconds expired.' % timeout
    except Exception as exc:
        logger.error('Command [%s] failed for unknown reasons [%s].' % (command, exc))
        logger.debug('Error:', exc_info=True)
        return None, exc
    else:
        logger.debug('Command [%s] returned with exit code [0]. Command output was:' % command)
        if output:
            logger.debug(output)
        return 0, output


# YOUR CODE HERE

executable = os.path.join(os.environ['SYSTEMROOT'], 'system32', 'robocopy.exe')
mycommand = '"%s" "%s" "%s" "%s"' % (executable, source, dest, options)
result, output = command_runner(mycommand, shell=True)

Answer 2

我发现了什么：感谢 QuantumChris。我发现从终端机复制 returns 并返回到我的脚本中，尽管我使用了 subprocess.run 应该暂停我的脚本直到它完成运行。在进行第二个 robocopy 之前，我通过检查文件是否已复制到目标文件夹来阻止运行的第二个 robocopy。问题是，如果最后一个文件很大，那么 os.path.isfile() 检测到文件 WHILE 时它仍在被复制。因此它使用第二个 robocopy 但是第二个 robocopy 没有检测到最后一个文件，因此尝试复制文件但认识到它无法访问该文件，因为它已经在使用中（由第一个 robocopy）所以它等待重试前 30 秒。 30 秒后，它可以访问该文件并将其复制过来。我现在想做的是让我的最后一个文件成为一个空的虚拟文件，我不关心它被复制两次，因为它是空的。 Robocopy 似乎根据 ASCII 顺序复制文件。所以我将文件命名为 ~~~~~.txt :D

Answer 3

尝试：

while temp2.poll() is not None:
    # ... do something else, sleep, etc

out, err = temp2.communicate()

让 python 等到 subprocess.call 完成它的命令

Making python wait until subprocess.call has finished its command

python

subprocess

call

popen

robocopy