Using fileinput to write to a file makes issue

Question

for line in fileinput.FileInput("file.txt", inplace=1):
  if "success" in line:
    print(line)

When I use fileinput, the file 'file.txt' is not released. I could see the issue 'file.txt' still in use. When I do the above function using normal file operation , no issue is shown

How to fix the issue with fileinput.

I used the below code snippet , but the issue is showing again . The file is not getting closed I guess

f = fileinput.input("file.txt", inplace=1)
    for line in f:
      if "success" in line:
      print(line)
    f.close()

Marijn · Accepted Answer · 2020-01-17 14:40:23Z

1

In Python 2.7, you have to explicitly call close() on the fileinput instance:

try:
  f = fileinput.input("file.txt", inplace=1)
    for line in f:
      if "success" in line:
        print line, end=""
else:
  f.close()

Since Python 3.2, the FileInput class can be used as a context manager. See the fileinput documentation for more information.

with fileinput.input(files=('file.txt'), inplace=1) as f:
  for line in f:
    if "success" in line:
      print(line)

edited Jan 17, 2020 at 14:40

answered Jan 14, 2020 at 12:01

Marijn

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10 Comments

Marijn Over a year ago

Note that fileinput is meant to be used with multiple files; when iterating over lines in a single file, you might as well use with file.open('file.txt') as f: ... f.readlines() ....

Paddy Over a year ago

@Marjin - Yeah , I Know that. I need to understand what is the issue here. Why fileinput throws such an issue.

Paddy Over a year ago

Thanks Marjin. The issue got resolved. My python version is 2.7 .

Marijn Over a year ago

I updated my Python 2.7 answer (see above); you should be good once you explicitly close the FileInput instance.

Marijn Over a year ago

Glad I could help. If my answer helped you, please use the check mark next to the answer to show others that your problem was solved. Welcome to StackOverflow!

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