Unable to Concatenate a file - destination kept getting overwritten

[Peter Otten]

Chris Angelico wrote:

> On Sat, Apr 21, 2012 at 11:03 AM, Foster Rilindo <rilindo at me.com> wrote:
>> Is this right way to concatenate a file or is there a better way?
> 
> I'd be inclined to ignore shutil and simply open one file for reading,
> the other for appending, and manually transfer data from one to the
> other.
> 
> open(disk1,"ab").write(open(disk2,"rb").read()) # untested
> 
> This one-liner doesn't explicitly close its files, doesn't check for
> errors, etc, etc, but it should give you the idea of what's going on.

The advantage of copyfileobj() is that it limits memory consumption:

>>> print inspect.getsource(shutil.copyfileobj)
def copyfileobj(fsrc, fdst, length=16*1024):
    """copy data from file-like object fsrc to file-like object fdst"""
    while 1:
        buf = fsrc.read(length)
        if not buf:
            break
        fdst.write(buf)