Unable to write data into a file using python

Question

outfile = open(inputfile, 'w')
outfile.write(argument)
outfile.flush()
os.fsync(outfile)
outfile.close

This is the code snippet. I am trying to write something into a file in python. but when we open the file, nothing is written into it. Am i doing anything wrong?

Why are you flushing `stdout`, and not closing the file object? — Martijn Pieters, Feb 14 '14 at 12:59
Is it a script, or you are trying in python shell? If it is a script, the file should be closed automatically on exit, so that shouldn't be the issue — Sunny Nanda, Feb 14 '14 at 13:02

Martijn Pieters · Accepted Answer · 2014-02-14T13:06:46.607

5

You are not calling the outfile.close method.

No need to flush here, just call close properly:

outfile = open(inputfile, 'w')
outfile.write(argument)
outfile.close()

or better still, use the file object as a context manager:

with open(inputfile, 'w') as outfile:
    outfile.write(argument)

This is all presuming that argument is not an empty string, and that you are looking at the right file. If you are using a relative path in inputfile what absolute path is used depends on your current working directory and you could be looking at the wrong file to see if something has been written to it.

edited Feb 14 '14 at 13:06

answered Feb 14 '14 at 13:00

Martijn Pieters

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Shouldn't the file be closed (and flushed) automatically on script exit ? – Sunny Nanda Feb 14 '14 at 13:04
@SunnyNanda: Yes, the file would also be closed when Python exits. There is no mention of that in the question though. I also mention that the presumption is that `argument` is not an empty string. – Martijn Pieters Feb 14 '14 at 13:05
@SunnyNanda: Added another assumption; that the OP is looking at the right file. – Martijn Pieters Feb 14 '14 at 13:07
Thank you Martjin Pieters. Your second option worked!! – A R Feb 14 '14 at 13:07
@user2599593: Then the first one would have worked too; all `file.__exit__()` does is call `self.close()`. `file.__exit__()` is called when the `with` block ends. – Martijn Pieters Feb 14 '14 at 13:08

score 1 · Answer 2 · answered Feb 14 '14 at 13:00

1

Try with

outfile.close()

note the brackets.

outfile.close

would only return the function-object and not really do anything.

answered Feb 14 '14 at 13:00

sebastian

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score 0 · Answer 3 · answered Feb 14 '14 at 13:07

You wont see the data you have written into it until you flush or close the file. And in your case, you are not flushing/closing the file properly.

* flush the file and not stdout - So you should invoke it as outfile.flush()
* close is a function. So you should invoke it as outfile.close()

So the correct snippet would be

  outfile = open(inputfile, 'w')
  outfile.write(argument)
  outfile.flush()
  outfile.close()

Unable to write data into a file using python

3 Answers3

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