Question

是否有任何python函数，例如：

filename = "a.txt"
if is_open(filename) and open_status(filename)=='w':
   print filename," is open for writing"

Answer 1

这不是你想要的，因为它只测试给定文件是否可写。但万一它有用：

import os

filename = "a.txt"
if not os.access(filename, os.W_OK):
    print "Write access not permitted on %s" % filename

（我不知道任何与平台无关的方式来做你要求的事情）

Answer 2

以下是使用ctypes的Windows的is_open解决方案：

from ctypes import cdll

_sopen = cdll.msvcrt._sopen
_close = cdll.msvcrt._close
_SH_DENYRW = 0x10

def is_open(filename):
    if not os.access(filename, os.F_OK):
        return False # file doesn't exist
    h = _sopen(filename, 0, _SH_DENYRW, 0)
    if h == 3:
        _close(h)
        return False # file is not opened by anyone else
    return True # file is already open

Answer 3

我认为没有一种简单的方法可以做你想要的，但一个开始可能是重新定义open（）并添加你自己的管理代码。那就是说，你为什么要那样做？

Answer 4

我认为最好的方法就是尝试。

/home/alaya/anaconda3/lib/python3.6/multiprocessing/reduction.py:153: RuntimeWarning: received malformed or improperly-truncated ancillary data
  msg, ancdata, flags, addr = sock.recvmsg(1, socket.CMSG_LEN(bytes_size))
Process ForkPoolWorker-3:
Traceback (most recent call last):
  File "/home/alaya/anaconda3/lib/python3.6/multiprocessing/process.py", line 258, in _bootstrap
    self.run()
  File "/home/alaya/anaconda3/lib/python3.6/multiprocessing/process.py", line 93, in run
    self._target(*self._args, **self._kwargs)
  File "/home/alaya/anaconda3/lib/python3.6/multiprocessing/pool.py", line 108, in worker
    task = get()
  File "/home/alaya/anaconda3/lib/python3.6/multiprocessing/queues.py", line 337, in get
    return _ForkingPickler.loads(res)
  File "/home/alaya/anaconda3/lib/python3.6/site-packages/torch/multiprocessing/reductions.py", line 151, in rebuild_storage_fd
    fd = df.detach()
  File "/home/alaya/anaconda3/lib/python3.6/multiprocessing/resource_sharer.py", line 58, in detach
    return reduction.recv_handle(conn)
  File "/home/alaya/anaconda3/lib/python3.6/multiprocessing/reduction.py", line 182, in recv_handle
    return recvfds(s, 1)[0]
  File "/home/alaya/anaconda3/lib/python3.6/multiprocessing/reduction.py", line 172, in recvfds
    raise RuntimeError('Invalid data received')
RuntimeError: Invalid data received
Traceback (most recent call last):
  File "/home/alaya/anaconda3/lib/python3.6/multiprocessing/resource_sharer.py", line 149, in _serve
  File "/home/alaya/anaconda3/lib/python3.6/multiprocessing/resource_sharer.py", line 50, in send
  File "/home/alaya/anaconda3/lib/python3.6/multiprocessing/reduction.py", line 176, in send_handle
  File "/home/alaya/anaconda3/lib/python3.6/socket.py", line 460, in fromfd
OSError: [Errno 24] Too many open files
Traceback (most recent call last):
  File "/home/alaya/anaconda3/lib/python3.6/multiprocessing/resource_sharer.py", line 142, in _serve
  File "/home/alaya/anaconda3/lib/python3.6/multiprocessing/connection.py", line 453, in accept
  File "/home/alaya/anaconda3/lib/python3.6/multiprocessing/connection.py", line 593, in accept
  File "/home/alaya/anaconda3/lib/python3.6/socket.py", line 205, in accept
OSError: [Errno 24] Too many open files
Traceback (most recent call last):
  File "/home/alaya/anaconda3/lib/python3.6/multiprocessing/resource_sharer.py", line 142, in _serve
  File "/home/alaya/anaconda3/lib/python3.6/multiprocessing/connection.py", line 453, in accept
  File "/home/alaya/anaconda3/lib/python3.6/multiprocessing/connection.py", line 593, in accept
  File "/home/alaya/anaconda3/lib/python3.6/socket.py", line 205, in accept
OSError: [Errno 24] Too many open files
Exception in thread Thread-1:
Traceback (most recent call last):
  File "/home/alaya/anaconda3/lib/python3.6/threading.py", line 916, in _bootstrap_inner
    self.run()
  File "/home/alaya/anaconda3/lib/python3.6/threading.py", line 864, in run
    self._target(*self._args, **self._kwargs)
  File "/home/alaya/anaconda3/lib/python3.6/multiprocessing/pool.py", line 405, in _handle_workers
    pool._maintain_pool()
  File "/home/alaya/anaconda3/lib/python3.6/multiprocessing/pool.py", line 246, in _maintain_pool
    self._repopulate_pool()
  File "/home/alaya/anaconda3/lib/python3.6/multiprocessing/pool.py", line 239, in _repopulate_pool
    w.start()
  File "/home/alaya/anaconda3/lib/python3.6/multiprocessing/process.py", line 105, in start
    self._popen = self._Popen(self)
  File "/home/alaya/anaconda3/lib/python3.6/multiprocessing/context.py", line 277, in _Popen
    return Popen(process_obj)
  File "/home/alaya/anaconda3/lib/python3.6/multiprocessing/popen_fork.py", line 19, in __init__
    self._launch(process_obj)
  File "/home/alaya/anaconda3/lib/python3.6/multiprocessing/popen_fork.py", line 65, in _launch
    parent_r, child_w = os.pipe()
OSError: [Errno 24] Too many open files

```

Answer 5

有一个属性可以检查文件的打开状态或模式。

filename = open('open.txt','r')
print(filename.mode)

Python 有一个名为“mode”的内置属性。上面的代码将返回'r'。同样，如果您以 'w' 模式打开文件，上面的代码将返回 'w'

您还可以检查文件是打开还是关闭

print(filename.closed)

这将返回“FALSE”，因为文件处于打开状态。

filename.closed
print(filename.closed)

这将返回“TRUE”，因为文件现在处于关闭状态。

谢谢

如何检查文件is_open和python中的open_status

5 个答案: