检查文件是否是python中的符号链接

Question

In python, is there a function to check if a given file/directory is a symlink ? For example, for the below files, my wrapper function should return True .

# ls -l
total 0
lrwxrwxrwx 1 root root 8 2012-06-16 18:58 dir -> ../temp/
lrwxrwxrwx 1 root root 6 2012-06-16 18:55 link -> ../log

Answer 1

To determine if a directory entry is a symlink use this:

os.path.islink(path)

Return True if path refers to a directory entry that is a symbolic link. Always False if symbolic links are not supported.

For instance, given:

drwxr-xr-x   2 root root  4096 2011-11-10 08:14 bin/
drwxrwxrwx   1 root root    57 2011-07-10 05:11 initrd.img -> boot/initrd.img-2..

>>> import os.path
>>> os.path.islink('initrd.img')
True
>>> os.path.islink('bin')
False

Answer 2

For python 3.4 and up, you can use the Path class

from pathlib import Path


# rpd is a symbolic link
>>> Path('rdp').is_symlink()
True
>>> Path('README').is_symlink()
False

You have to be careful when using the is_symlink() method. It will return True even the target of the link is non-existent as long as the the named object is a symlink. For example (Linux/Unix):

ln -s ../nonexistentfile flnk

Then, in your current directory fire up python

>>> from pathlib import Path
>>> Path('flnk').is_symlink()
True
>>> Path('flnk').exists()
False

The programmer has to decide what he/she realy wants. Python 3 seems to have renamed a lots of classes. It might be worthwhile to read the manual page for the Path class: https://docs.python.org/3/library/pathlib.html

Answer 3

Without the intention to bloat this topic, but I was redirected to this page as I was looking for symlink's to find them and convert them to real files and found this script within the python tools library.

#Source https://github.com/python/cpython/blob/master/Tools/scripts/mkreal.py


import sys
import os
from stat import *

BUFSIZE = 32*1024

def mkrealfile(name):
    st = os.stat(name) # Get the mode
    mode = S_IMODE(st[ST_MODE])
    linkto = os.readlink(name) # Make sure again it's a symlink
    f_in = open(name, 'r') # This ensures it's a file
    os.unlink(name)
    f_out = open(name, 'w')
    while 1:
        buf = f_in.read(BUFSIZE)
        if not buf: break
        f_out.write(buf)
    del f_out # Flush data to disk before changing mode
    os.chmod(name, mode)

    mkrealfile("/Users/test/mysymlink")