将文件移动到子目录时，os.rename路径错误

Question

I am new to python and coding in general. I have spent a lot of time trying to fix this error but I am not able to figure out how to do this. I have a main folder that contains a subfolder, I want to move files from the main folder to subfolder. This should be done easily by os.rename or shutil.move but I am not able to fix this error. Below is the code that I am using and the error that I am getting.

cdir=os.getcwd()
newdir=cdir+"\subfolder"
src=os.path.join(cdir, fname) 
dst=os.path.join(newdir, fname)
os.rename(src,dst)

The error shows a double backslash in the directories path ie

FileNotFoundError: [WinError 3] The system cannot find the path specified: 'E:\\\\ folder\\\\fname' -> 'E:\\\\folder\\\\subfolder\\\\fname'

the correct path would be with single back slashes. I am using windows 8.1 and python34. Can any one help me with this. I know this question must be a duplicate but I am unable to understand what I am doing wrong. Similar error is generated with shutil.move

Answer 1

The double backslashes are normal ; they are not the cause of the error. Python always doubles up backslashes in string representations so that you can safely copy that value into a Python interpreter and reproduce the exact string:

>>> print 'E:\\folder\\fname' 
E:\folder\fname
>>> 'E:\\folder\\fname' 
'E:\\folder\\fname'
>>> value = 'E:\\folder\\fname' 
>>> value
'E:\\folder\\fname'
>>> print value
E:\folder\fname

Python does this because a single backslash is used in escape sequences; '\\n' is a newline, but '\\\\n' is a backslash and the letter n .

Your error lies elsewhere; most likely the subfolder has yet to be created; os.rename() or shutil.move() will not create parent folders for you.

You can use the os.makedirs() function to ensure that all folders in a path are created:

newdir = os.path.abspath('subfolder')  # will use the current working directory
try:
    # ensure that it exists
    os.makedirs(newdir)
except OSError:
    pass  # it is already there
src = os.path.abspath(fname) 
dst = os.path.join(newdir, fname)
os.rename(src, dst)

You also need to make sure you don't accidentally use single backslashes in your filename or subfolder definitions; \\s is not a valid escape, but others are valid and can produce unexpected results. Double the backslash in strings defining paths, or use a raw string literal , or use forward slashes instead:

>>> '\new'  # newline!
'\new'
>>> print '\new'  # produces a blank line in between

ew
>>> '\\new'
'\\new'
>>> print '\\new'
\new
>>> r'\new'
'\\new'
>>> '/new'
'/new'

Windows accepts forward slashes just fine; it doesn't care if the path separator is pointing forward or backward.