If the reason you're checking is so you can do something like if file_exists: open_it()
, it's safer to use a try
around the attempt to open it. Checking and then opening risks the file being deleted or moved or something between when you check and when you try to open it.
If you're not planning to open the file immediately, you can use os.path.isfile
Return True
if path is an existing regular file. This follows symbolic links, so both islink() and isfile() can be true for the same path.
import os.path
os.path.isfile(fname)
if you need to be sure it's a file.
Starting with Python 3.4, the pathlib
module offers an object-oriented approach (backported to pathlib2
in Python 2.7):
from pathlib import Path
my_file = Path("/path/to/file")
if my_file.is_file():
# file exists
To check a directory, do:
if my_file.is_dir():
# directory exists
To check whether a Path
object exists independently of whether is it a file or directory, use exists()
:
if my_file.exists():
# path exists
You can also use resolve(strict=True)
in a try
block:
try:
my_abs_path = my_file.resolve(strict=True)
except FileNotFoundError:
# doesn't exist
else:
# exists
shutil
has many methods you can use. One of which is:
from shutil import copyfile
copyfile(src, dst)
# 2nd option
copy(src, dst) # dst can be a folder; use 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 str
s.
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.
Best Answer
Check out this documentation here: http://drupal.org/documentation/modules/file
Specifically, the section titled "Managing file locations and access" which talks about setting up a private data store (all supported by Drupal 7, it just needs to be configured).
To paraphrase, create a folder such as:
sites/default/files/private
Put a .htaccess file in that folder with the following to prevent direct access to the files via the web:
Deny from all
(the documentation claims that the following step does the above steps automatically, I haven't tested that unfortunately but you may be able to save some time if you skip the above two steps)
Log into Drupal's admin interface, go to /admin/config/media/file-system, configure the private URL and select Private Files Served by Drupal as the default download method.
In order to define the fine-grained access to nodes and fields, you can use Content Access: http://drupal.org/project/content_access
You will also need to edit your content types and set the file / image upload fields to save the uploaded files into Private Files instead of Public Files.
At this point, the node and field level permissions will determine whether or not users are allowed to access the files which will be served through menu hooks that verify credentials before serving the file.
Hope this helps.