用os.path.join()构造绝对路径 [英] constructing absolute path with os.path.join()

问题描述

我想在python中构造一个绝对路径，而与此同时却对诸如路径分隔符之类的东西一无所知.

I'd like to construct an absolute path in python, while at the same time staying fairly oblivious of things like path-separator.

edit0 :例如，在我的文件系统/etc/init.d(或w32上的C:\etc\init.d)的根目录中有一个目录，我只想从元素etc和init.d(在w32上，我可能还需要一个磁盘ID，例如C:)

edit0: for instance there is a directory on the root of my filesystem /etc/init.d (or C:\etc\init.d on w32), and I want to construct this only from the elements etc and init.d (on w32, I probably also need a disk-ID, like C:)

为了不必担心路径分隔符，os.join.path()显然是首选工具.但这似乎只会创建相对路径:

In order to not having to worry about path-separators, os.join.path() is obviously the tool of choice. But it seems that this will only ever create relative paths:

 print "MYPATH:", os.path.join('etc', 'init.d')
 MYPATH: etc/init.d

添加虚拟的第一元素(例如'')无济于事:

Adding a dummy first-element (e.g. '') doesn't help anything:

 print "MYPATH:", os.path.join('', 'etc', 'init.d')
 MYPATH: etc/init.d

将第一个元素设为绝对显然会有所帮助，但这种做法破坏了使用os.path.join()

Making the first element absolute obviously helps, but this kind of defeats the idea of using os.path.join()

 print "MYPATH:", os.path.join('/etc', 'init.d')
 MYPATH: /etc/init.d

edit1 :使用os.path.abspath()只会尝试将相对路径转换为绝对路径. 例如考虑在工作目录/home/foo中运行以下命令:

edit1: using os.path.abspath() will only try to convert a relative path into an absolute path. e.g. consider running the following in the working directory /home/foo:

 print "MYPATH:", os.path.abspath(os.path.join('etc', 'init.d'))
 MYPATH: /home/foo/etc/init.d

那么，扎根"路径的标准跨平台方法是什么?

So, what is the standard cross-platform way to "root" a path?

 root = ??? # <--
 print "MYPATH:", os.path.join(root, 'etc', 'init.d')
 MYPATH: /etc/init.d

edit2 :问题的实质可以归结为:由于/etc/init.d中的前导斜线使该路径成为绝对路径，是否有办法以编程方式构造该前导斜线? (我不想假设斜杠表示绝对路径)

edit2: the question really boils down to: since the leading slash in /etc/init.d makes this path an absolute path, is there a way to construct this leading slash programmatically? (I do not want to make assumptions that a leading slash indicates an absolute path)

推荐答案

所以我想到的解决方案是，通过将给定文件放在根目录下来构造文件系统的根目录:

so the solution i came up with, is to construct the root of the filesystem by following a given file to it's root:

def getRoot(file=None):
  if file is None:
      file='.'
  me=os.path.abspath(file)
  drive,path=os.path.splitdrive(me)
  while 1:
    path,folder=os.path.split(path)
    if not folder:
       break
  return drive+path

 os.path.join(getRoot(), 'etc', 'init.d')

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