使用Jupyter notebook時執行此段程式碼：

from subprocess import check_output
print(check_output(["ls", "C:/Kaggle/Titanic/input"]).decode("utf8"))

出現錯誤：

FileNotFoundError                         Traceback (most recent call last)
<ipython-input-10-cf7fc002cdae> in <module>()
     32 # input directory
     33 from subprocess import check_output
---> 34 print(check_output(["ls", "C:/Kaggle/Titanic/input"]).decode("utf8"))
     35 #import os
     36 #print(os.listdir('C:/Kaggle/Titanic/input'))

~\Anaconda3\lib\subprocess.py in check_output(timeout, *popenargs, **kwargs)
    374 
    375     return run(*popenargs, stdout=PIPE, timeout=timeout, check=True,
--> 376                **kwargs).stdout
    377 
    378 

~\Anaconda3\lib\subprocess.py in run(input, capture_output, timeout, check, *popenargs, **kwargs)
    451         kwargs['stderr'] = PIPE
    452 
--> 453     with Popen(*popenargs, **kwargs) as process:
    454         try:
    455             stdout, stderr = process.communicate(input, timeout=timeout)

~\Anaconda3\lib\subprocess.py in __init__(self, args, bufsize, executable, stdin, stdout, stderr, preexec_fn, close_fds, shell, cwd, env, universal_newlines, startupinfo, creationflags, restore_signals, start_new_session, pass_fds, encoding, errors, text)
    754                                 c2pread, c2pwrite,
    755                                 errread, errwrite,
--> 756                                 restore_signals, start_new_session)
    757         except:
    758             # Cleanup if the child failed starting.

~\Anaconda3\lib\subprocess.py in _execute_child(self, args, executable, preexec_fn, close_fds, pass_fds, cwd, env, startupinfo, creationflags, shell, p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite, unused_restore_signals, unused_start_new_session)
   1153                                          env,
   1154                                          os.fspath(cwd) if cwd is not None else None,
-> 1155                                          startupinfo)
   1156             finally:
   1157                 # Child is launched. Close the parent's copy of those pipe

FileNotFoundError: [WinError 2] 系統找不到指定的檔案。
 

• 原因

因為使用的是Windows，預設情況下，Windows不符合POSIX。例如，沒有ls二進位制檔案。因此，子程序無法找到該檔案ls，從而發出一個FileNotFoundError。

• 解決辦法

1. 列出目錄的更便攜的方法是使用os.listdir：

import os
print(os.listdir('C:/Kaggle/Titanic/input'))

結果展示：[‘gender_submission.csv’, ‘test.csv’, ‘train.csv’]