Python: Write all file names in a directory and its subdirectories into a text file

Question

My problem is as follows. I want to list all the file names in my directory and its subdirectories and have that output printed in a txt file. Now this is the code I have so far:

import os

for path, subdirs, files in os.walk('\Users\user\Desktop\Test_Py'):
   for filename in files:
     f = os.path.join(path, filename)
     a = open("output.txt", "w")
     a.write(str(f))

This lists the names of the files in the folders (there are 6) but each new file overwrites the old so there is only one file name in the output.txt file at any given time. How do I change this code so that it writes all of the file names in the output.txt file?

Did you search SO? I was just reading almost an exact duplicate of this from a while ago... — Austin Henley, Sep 26 '12 at 22:08

score 37 · Accepted Answer · edited Aug 30 '12 at 16:23

37

don't open a file in your for loop. open it before your for loop

like this

import os

a = open("output.txt", "w")
for path, subdirs, files in os.walk(r'C:\Users\user\Desktop\Test_Py'):
   for filename in files:
     f = os.path.join(path, filename)
     a.write(str(f) + os.linesep)

Or using a context manager (which is better practice):

import os

with open("output.txt", "w") as a:
    for path, subdirs, files in os.walk(r'C:\Users\user\Desktop\Test_Py'):
       for filename in files:
         f = os.path.join(path, filename)
         a.write(str(f) + os.linesep)

edited Aug 30 '12 at 16:23

brian buck

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answered Aug 30 '12 at 14:25

gefei

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5

And you should be opening a file using the `with` statement so that the file will close automatically when the loops finish. – brian buck Aug 30 '12 at 14:28
2

it's better to use ***with*** while the opened file will be closed after complete the process. i.e., "with open("output.txt", "w") as a" – John Wang Aug 30 '12 at 14:30
Might want some linebreaks in there somewhere, too. :^) – DSM Aug 30 '12 at 14:35

score 6 · Answer 2 · edited Aug 30 '12 at 14:30

6

You are opening the file in write mode. You need append mode. See the manual for details.

change

a = open("output.txt", "w")

to

a = open("output.txt", "a")

edited Aug 30 '12 at 14:30

Mike Mackintosh

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answered Aug 30 '12 at 14:25

Emmett Butler

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score 2 · Answer 3 · answered Mar 15 '13 at 08:41

2

You can use below code to write only File name from a folder.

import os

a = open("output.txt", "w")
for path, subdirs, files in os.walk(r'C:\temp'):
   for filename in files:
      a.write(filename + os.linesep)

answered Mar 15 '13 at 08:41

CRitesh

21
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Jeru Luke · Answer 4 · 2022-05-16T12:45:34.087

If you want to avoid creating new lines in the text file include newline='' within the context manager. You won't have to format your text file later.

Code to write names of all files in a folder/directory:

file_path = 'path_containing_files'
with open("Filenames.txt", mode='w', newline='') as fp:
    for file in os.listdir(file_path):
        f = os.path.join(file_path, file)
        fp.write(str(f) + os.linesep)

If you want to write the file names of a particular file type eg. XML, you can add an if condition:

file_path = 'path_containing_files'
with open("Filenames.txt", mode='w', newline='') as fp:
    for file in os.listdir(file_path):
        if file.endswith('.xml'):
            f = os.path.join(file_path, file)
            fp.write(str(f) + os.linesep)

Python: Write all file names in a directory and its subdirectories into a text file

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