How to copy files

shutil has many methods you can use. One of which is:

import shutil

shutil.copyfile(src, dst)

# 2nd option
shutil.copy(src, dst)  # dst can be a folder; use shutil.copy2() to preserve timestamp

• Copy the contents of the file named src to a file named dst. Both src and dst need to be the entire filename of the files, including path.
• The destination location must be writable; otherwise, an IOError exception will be raised.
• If dst already exists, it will be replaced.
• Special files such as character or block devices and pipes cannot be copied with this function.
• With copy, src and dst are path names given as strs.

Another shutil method to look at is shutil.copy2(). It's similar but preserves more metadata (e.g. time stamps).

If you use os.path operations, use copy rather than copyfile. copyfile will only accept strings.

copy2(src,dst) is often more useful than copyfile(src,dst) because:

• it allows dst to be a directory (instead of the complete target filename), in which case the basename of src is used for creating the new file;
• it preserves the original modification and access info (mtime and atime) in the file metadata (however, this comes with a slight overhead).

Here is a short example:

import shutil
shutil.copy2('/src/dir/file.ext', '/dst/dir/newname.ext') # complete target filename given
shutil.copy2('/src/file.ext', '/dst/dir') # target filename is /dst/dir/file.ext

In Python, you can copy the files using

• shutil module
• os module
• subprocess module

import os
import shutil
import subprocess

1) Copying files using shutil module

shutil.copyfile signature

shutil.copyfile(src_file, dest_file, *, follow_symlinks=True)

# example    
shutil.copyfile('source.txt', 'destination.txt')

shutil.copy signature

shutil.copy(src_file, dest_file, *, follow_symlinks=True)

# example
shutil.copy('source.txt', 'destination.txt')

shutil.copy2 signature

shutil.copy2(src_file, dest_file, *, follow_symlinks=True)

# example
shutil.copy2('source.txt', 'destination.txt')  

shutil.copyfileobj signature

shutil.copyfileobj(src_file_object, dest_file_object[, length])

# example
file_src = 'source.txt'  
f_src = open(file_src, 'rb')

file_dest = 'destination.txt'  
f_dest = open(file_dest, 'wb')

shutil.copyfileobj(f_src, f_dest)  

2) Copying files using os module

os.popen signature

os.popen(cmd[, mode[, bufsize]])

# example
# In Unix/Linux
os.popen('cp source.txt destination.txt') 

# In Windows
os.popen('copy source.txt destination.txt')

os.system signature

os.system(command)


# In Linux/Unix
os.system('cp source.txt destination.txt')  

# In Windows
os.system('copy source.txt destination.txt')

3) Copying files using subprocess module

subprocess.call signature

subprocess.call(args, *, stdin=None, stdout=None, stderr=None, shell=False)

# example (WARNING: setting `shell=True` might be a security-risk)
# In Linux/Unix
status = subprocess.call('cp source.txt destination.txt', shell=True) 

# In Windows
status = subprocess.call('copy source.txt destination.txt', shell=True)

subprocess.check_output signature

subprocess.check_output(args, *, stdin=None, stderr=None, shell=False, universal_newlines=False)

# example (WARNING: setting `shell=True` might be a security-risk)
# In Linux/Unix
status = subprocess.check_output('cp source.txt destination.txt', shell=True)

# In Windows
status = subprocess.check_output('copy source.txt destination.txt', shell=True)

You can use one of the copy functions from the shutil package:

━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
Function              preserves     supports          accepts     copies other
                      permissions   directory dest.   file obj    metadata  
――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――
shutil.copy              ✔             ✔                 ☐           ☐
shutil.copy2             ✔             ✔                 ☐           ✔
shutil.copyfile          ☐             ☐                 ☐           ☐
shutil.copyfileobj       ☐             ☐                 ✔           ☐
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

Example:

import shutil
shutil.copy('/etc/hostname', '/var/tmp/testhostname')

Copying a file is a relatively straightforward operation as shown by the examples below, but you should instead use the shutil stdlib module for that.

def copyfileobj_example(source, dest, buffer_size=1024*1024):
    """      
    Copy a file from source to dest. source and dest
    must be file-like objects, i.e. any object with a read or
    write method, like for example StringIO.
    """
    while True:
        copy_buffer = source.read(buffer_size)
        if not copy_buffer:
            break
        dest.write(copy_buffer)

If you want to copy by filename you could do something like this:

def copyfile_example(source, dest):
    # Beware, this example does not handle any edge cases!
    with open(source, 'rb') as src, open(dest, 'wb') as dst:
        copyfileobj_example(src, dst)

Use the shutil module.

copyfile(src, dst)

Copy the contents of the file named src to a file named dst. The destination location must be writable; otherwise, an IOError exception will be raised. If dst already exists, it will be replaced. Special files such as character or block devices and pipes cannot be copied with this function. src and dst are path names given as strings.

Take a look at filesys for all the file and directory handling functions available in standard Python modules.

Directory and File copy example, from Tim Golden's Python Stuff:

import os
import shutil
import tempfile

filename1 = tempfile.mktemp (".txt")
open (filename1, "w").close ()
filename2 = filename1 + ".copy"
print filename1, "=>", filename2

shutil.copy (filename1, filename2)

if os.path.isfile (filename2): print "Success"

dirname1 = tempfile.mktemp (".dir")
os.mkdir (dirname1)
dirname2 = dirname1 + ".copy"
print dirname1, "=>", dirname2

shutil.copytree (dirname1, dirname2)

if os.path.isdir (dirname2): print "Success"

For small files and using only Python built-ins, you can use the following one-liner:

with open(source, 'rb') as src, open(dest, 'wb') as dst: dst.write(src.read())

This is not optimal way for applications where the file is too large or when memory is critical, thus Swati's answer should be preferred.

Firstly, I made an exhaustive cheat sheet of the shutil methods for your reference.

shutil_methods =
{'copy':['shutil.copyfileobj',
          'shutil.copyfile',
          'shutil.copymode',
          'shutil.copystat',
          'shutil.copy',
          'shutil.copy2',
          'shutil.copytree',],
 'move':['shutil.rmtree',
         'shutil.move',],
 'exception': ['exception shutil.SameFileError',
                 'exception shutil.Error'],
 'others':['shutil.disk_usage',
             'shutil.chown',
             'shutil.which',
             'shutil.ignore_patterns',]
}

Secondly, explaining methods of copy in examples:

1. shutil.copyfileobj(fsrc, fdst[, length]) manipulate opened objects

   In [3]: src = '~/Documents/Head+First+SQL.pdf'
   In [4]: dst = '~/desktop'
   In [5]: shutil.copyfileobj(src, dst)
   AttributeError: 'str' object has no attribute 'read'
   
   # Copy the file object
   In [7]: with open(src, 'rb') as f1,open(os.path.join(dst,'test.pdf'), 'wb') as f2:
       ...:      shutil.copyfileobj(f1, f2)
   In [8]: os.stat(os.path.join(dst,'test.pdf'))
   Out[8]: os.stat_result(st_mode=33188, st_ino=8598319475, st_dev=16777220, st_nlink=1, st_uid=501, st_gid=20, st_size=13507926, st_atime=1516067347, st_mtime=1516067335, st_ctime=1516067345)
   

2. shutil.copyfile(src, dst, *, follow_symlinks=True) Copy and rename

   In [9]: shutil.copyfile(src, dst)
   IsADirectoryError: [Errno 21] Is a directory: ~/desktop'
   # So dst should be a filename instead of a directory name
   

3. shutil.copy() Copy without preseving the metadata

   In [10]: shutil.copy(src, dst)
   Out[10]: ~/desktop/Head+First+SQL.pdf'
   
   # Check their metadata
   In [25]: os.stat(src)
   Out[25]: os.stat_result(st_mode=33188, st_ino=597749, st_dev=16777220, st_nlink=1, st_uid=501, st_gid=20, st_size=13507926, st_atime=1516066425, st_mtime=1493698739, st_ctime=1514871215)
   In [26]: os.stat(os.path.join(dst, 'Head+First+SQL.pdf'))
   Out[26]: os.stat_result(st_mode=33188, st_ino=8598313736, st_dev=16777220, st_nlink=1, st_uid=501, st_gid=20, st_size=13507926, st_atime=1516066427, st_mtime=1516066425, st_ctime=1516066425)
   # st_atime,st_mtime,st_ctime changed
   

4. shutil.copy2() Copy with preserving the metadata

   In [30]: shutil.copy2(src, dst)
   Out[30]: ~/desktop/Head+First+SQL.pdf'
   In [31]: os.stat(src)
   Out[31]: os.stat_result(st_mode=33188, st_ino=597749, st_dev=16777220, st_nlink=1, st_uid=501, st_gid=20, st_size=13507926, st_atime=1516067055, st_mtime=1493698739, st_ctime=1514871215)
   In [32]: os.stat(os.path.join(dst, 'Head+First+SQL.pdf'))
   Out[32]: os.stat_result(st_mode=33188, st_ino=8598313736, st_dev=16777220, st_nlink=1, st_uid=501, st_gid=20, st_size=13507926, st_atime=1516067063, st_mtime=1493698739, st_ctime=1516067055)
   # Preserved st_mtime
   

5. shutil.copytree()

   Recursively copy an entire directory tree rooted at src, returning the destination directory.

As of Python 3.5 you can do the following for small files (ie: text files, small jpegs):

from pathlib import Path

source = Path('../path/to/my/file.txt')
destination = Path('../path/where/i/want/to/store/it.txt')
destination.write_bytes(source.read_bytes())

write_bytes will overwrite whatever was at the destination's location

You could use os.system('cp nameoffilegeneratedbyprogram /otherdirectory/').

Or as I did it,

os.system('cp '+ rawfile + ' rawdata.dat')

where rawfile is the name that I had generated inside the program.

This is a Linux-only solution.

There are two best ways to copy file in Python.

1. We can use the shutil module

Code Example:

import shutil
shutil.copyfile('/path/to/file', '/path/to/new/file')

There are other methods available also other than copyfile, like copy, copy2, etc, but copyfile is best in terms of performance,

2. We can use the OS module

Code Example:

import os
os.system('cp /path/to/file /path/to/new/file')

Another method is by the use of a subprocess, but it is not preferable as it’s one of the call methods and is not secure.

Use

open(destination, 'wb').write(open(source, 'rb').read())

Open the source file in read mode, and write to the destination file in write mode.

Use subprocess.call to copy the file

from subprocess import call
call("cp -p <file> <file>", shell=True)

For large files, I read the file line by line and read each line into an array. Then, once the array reached a certain size, append it to a new file.

for line in open("file.txt", "r"):
    list.append(line)
    if len(list) == 1000000: 
        output.writelines(list)
        del list[:]

In case you've come this far down. The answer is that you need the entire path and file name

import os

shutil.copy(os.path.join(old_dir, file), os.path.join(new_dir, file))

Here is a simple way to do it, without any module. It's similar to this answer, but has the benefit to also work if it's a big file that doesn't fit in RAM:

with open('sourcefile', 'rb') as f, open('destfile', 'wb') as g:
    while True:
        block = f.read(16*1024*1024)  # work by blocks of 16 MB
        if not block:  # end of file
            break
        g.write(block)

Since we're writing a new file, it does not preserve the modification time, etc.
We can then use os.utime for this if needed.

Similar to the accepted answer, the following code block might come in handy if you also want to make sure to create any (non-existent) folders in the path to the destination.

from os import path, makedirs
from shutil import copyfile
makedirs(path.dirname(path.abspath(destination_path)), exist_ok=True)
copyfile(source_path, destination_path)

As the accepted answers notes, these lines will overwrite any file which exists at the destination path, so sometimes it might be useful to also add: if not path.exists(destination_path): before this code block.

I would like to propose a different solution.

def copy(source, destination):
   with open(source, 'rb') as file:
       myFile = file.read()
   with open(destination, 'wb') as file:
       file.write(myFile)

copy("foo.txt", "bar.txt")

The file is opened, and it's data is written to a new file of your choosing.

For the answer everyone recommends, if you prefer not to use the standard modules, or have completely removed them as I've done, preferring more core C methods over poorly written python methods

The way shutil works is symlink/hardlink safe, but is rather slow due to os.path.normpath() containing a while (nt, mac) or for (posix) loop, used in testing if src and dst are the same in shutil.copyfile()

This part is mostly unneeded if you know for certain src and dst will never be the same file, otherwise a faster C approach could potentially be used.
(note that just because a module may be C doesn't inherently mean it's faster, know that what you use is actually written well before you use it)

After that initial testing, copyfile() runs a for loop on a dynamic tuple of (src, dst), testing for special files (such as sockets or devices in posix).

Finally, if follow_symlinks is False, copyfile() tests if src is a symlink with os.path.islink(), which varies between nt.lstat() or posix.lstat() (os.lstat()) on Windows and Linux, or Carbon.File.ResolveAliasFile(s, 0)[2] on Mac.
If that test resolves True, the core code that copies a symlink/hardlink is:

        os.symlink(os.readlink(src), dst)

Hardlinks in posix are done with posix.link(), which shutil.copyfile() doesn't call, despite being callable through os.link().
(probably because the only way to check for hardlinks is to hashmap the os.lstat() (st_ino and st_dev specifically) of the first inode we know about, and assume that's the hardlink target)

Else, file copying is done via basic file buffers:

       with open(src, 'rb') as fsrc:
           with open(dst, 'wb') as fdst:
               copyfileobj(fsrc, fdst)

(similar to other answers here)

copyfileobj() is a bit special in that it's buffer safe, using a length argument to read the file buffer in chunks:

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)

Hope this answer helps shed some light on the mystery of file copying using core mechanisms in python. :)

Overall, shutil isn't too poorly written, especially after the second test in copyfile(), so it's not a horrible choice to use if you're lazy, but the initial tests will be a bit slow for a mass copy due to the minor bloat.