Can I save a text file in python without closing it?

Question

I am writing a program in which I would like to be able to view a log file before the program is complete. I have noticed that, in python (2.7 and 3), that file.write(

Answer 1

You would need this:

file.flush()
# typically the above line would do. however this is used to ensure that the file is written
os.fsync(file.fileno())

Check this: http://docs.python.org/2/library/stdtypes.html#file.flush

file.flush() Flush the internal buffer, like stdio‘s fflush(). This may be a no-op on some file-like objects. Note flush() does not necessarily write the file’s data to disk. Use flush() followed by os.fsync() to ensure this behavior.

EDITED: See this question for detailed explanations: what exactly the python's file.flush() is doing?

Answer 2

This will write the file to disk immediately:

file.flush()
os.fsync(file.fileno())

According to the documentation https://docs.python.org/2/library/os.html#os.fsync

Force write of file with filedescriptor fd to disk. On Unix, this calls the native fsync() function; on Windows, the MS _commit() function.

If you’re starting with a Python file object f, first do f.flush(), and then do os.fsync(f.fileno()), to ensure that all internal buffers associated with f are written to disk.

Answer 3

Does file.flush() after each write help?

Hannu