I've run this code but it only writes in the text file the first directory in /home
for item in os.listdir('/home'):
text_file_1 = open('/tmp/home_dir.txt', 'wb')
text_file_1.write('%s\n' % item)
text_file_1.close()
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Well you close the file after you write one line.squiguy– squiguy2014-02-25 18:13:57 +00:00Commented Feb 25, 2014 at 18:13
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it should actually write the last one.njzk2– njzk22014-02-25 18:29:32 +00:00Commented Feb 25, 2014 at 18:29
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2 Answers
You should open the file outside the loop. Otherwise you "start over" every time you open it
Context managers (with statement) are the preferred way to open files
with open('/tmp/home_dir.txt', 'w') as text_file_1:
for item in os.listdir('/home'):
text_file_1.write('%s\n' % item)
7 Comments
mgilson
or,
text_file_1.writelines(fname + '\n' for fname in os.listdir('/home'))
mhlester
That will certainly work as well, but I think this is clearer for beginners
mhlester
@mgilson's answer is shorter, and mine is clearer. Whichever you feel comfortable with. Functionally they're nearly identical.
mgilson
@mhlester -- Gotta learn comprehensions sometime. No better time than right now... :-)
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I think you'll find it's the last item from os.listdir().
try this:
text_file_1 = open('/tmp/home_dir.txt', 'w')
for item in os.listdir('/home'):
text_file_1.write('%s\n' % item)
text_file_1.close()
Or this:
for item in os.listdir('/home'):
text_file_1 = open('/tmp/home_dir.txt', 'a')
text_file_1.write('%s\n' % item)
text_file_1.close()
When you open the new file handle and write to the file with 'w', it completely overwrites what was originally in it.
'a' allows you to append to the file.
I would recommend my first solution; opening and closing files is costly. If you're going to rapidly loop over items to write to a file you may as well keep it open.
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