如何在Python中复制文件？

How do I copy a file in Python?

I couldn’t find anything under os.

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

from shutil import copyfile
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.
• With copy, src and dst are path names given as strings.

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

┌──────────────────┬────────┬───────────┬───────┬────────────────┐
│     Function     │ Copies │   Copies  │Can use│   Destination  │
│                  │metadata│permissions│buffer │may be directory│
├──────────────────┼────────┼───────────┼───────┼────────────────┤
│shutil.copy       │   No   │    Yes    │   No  │      Yes       │
│shutil.copyfile   │   No   │     No    │   No  │       No       │
│shutil.copy2      │  Yes   │    Yes    │   No  │      Yes       │
│shutil.copyfileobj│   No   │     No    │  Yes  │       No       │
└──────────────────┴────────┴───────────┴───────┴────────────────┘

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

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')

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)

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:

http://timgolden.me.uk/python/win32_how_do_i/copy-a-file.html

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"

Firstly, I made an exhaustive cheatsheet of 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, explain methods of copy in exmaples:

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 preseving 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)
# Preseved st_mtime

5. shutil.copytree()

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

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())

As @maxschlepzig mentioned in the comments below, 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.

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

For large files, what I did was 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[:]

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

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

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

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

Python provides in-built functions for easily copying files using the Operating System Shell utilities.

Following command is used to Copy File

shutil.copy(src,dst)

Following command is used to Copy File with MetaData Information

shutil.copystat(src,dst)