Python - 'str' object has no attribute 'close'

file_content is a string variable, which contains contents of the file -- it has no relation to the file. The file descriptor you open with open(from_file) will be closed automatically: file sessions are closed after the file-objects exit the scope (in this case, immediately after .read()).

open(...) returns a reference to a file object, calling read on that reads the file returning a string object, calling write writes to it returning None, neither of which have a close attribute.

>>> help(open)
Help on built-in function open in module __builtin__:

open(...)
    open(name[, mode[, buffering]]) -> file object

    Open a file using the file() type, returns a file object.  This is the
    preferred way to open a file.

>>> a = open('a', 'w')
>>> help(a.read)
read(...)
    read([size]) -> read at most size bytes, returned as a string.

    If the size argument is negative or omitted, read until EOF is reached.
    Notice that when in non-blocking mode, less data than what was requested
    may be returned, even if no size parameter was given.
>>> help(a.write)
Help on built-in function write:

write(...)
    write(str) -> None.  Write string str to file.

    Note that due to buffering, flush() or close() may be needed before
    the file on disk reflects the data written.

Theres a couple ways of remedying this:

>>> file = open(from_file)
>>> content = file.read()
>>> file.close()

or with python >= 2.5

>>> with open(from_file) as f:
...     content = f.read()

The with will make sure the file is closed.

When you do file_content = open(from_file).read(), you set file_content to the contents of the file (as read by read). You can't close this string. You need to save the file object separately from its contents, something like:

theFile = open(from_file)
file_content = theFile.read()
# do whatever you need to do
theFile.close()

You have a similar problem with new_file. You should separate the open(to_file) call from the write.