When using bash, the `cd` function does not follow symlinks by default, but `cd -P` does. The `os.chdir` function behaves like `cd -P` preventing to be able to change directory to a symlink folder.

Initial setup (make a `/tmp/to/dst` symlink pointing to `/tmp/from/src`):

    cd /tmp
    mkdir from from/src to
    ln -s ../from/src to/dst

Here is an example, when using python's `os.chdir` function:

    [fabien@asus ~]$ python
    >>> import os
    >>> os.chdir('/tmp/to/dst')
    >>> os.system('/usr/bin/pwd')
    /tmp/from/src
    0
    >>> os.system('/usr/bin/pwd -P')
    /tmp/from/src
    0
    >>> os.system('/usr/bin/pwd -L')
    /tmp/from/src
    0
    >>> os.getcwd()
    '/tmp/from/src'
    >>> 

And here is an example when the folder is first changed with bash:


    [fabien@asus ~]$ cd /tmp/to/dst/
    [fabien@asus dst]$ python
    >>> import os
    >>> os.system('/usr/bin/pwd')
    /tmp/from/src
    0
    >>> os.system('/usr/bin/pwd -P')
    /tmp/from/src
    0
    >>> os.system('/usr/bin/pwd -L')
    /tmp/to/dst
    0
    >>> os.getcwd()
    '/tmp/from/src'
    >>>

The previous example (sorry, first time using this platform, I'm a little bit messy here), shows that `os.chdir` resolves symlinks by default, as opposed to what `cd` does in bash. This means it is not possible to change the directory to a symlink folder.

A solution would be a keyword argument in `os.chdir` and `os.getcwd` that would mimic the `-P` and `-L` arguments of `cd` and `pwd`, like:

    os.chdir(logical=False)  # or follow_symlinks=True maybe
    os.getcwd(logical=False)

I don't know what should be the default values for these args, but at least having an option to change the behavior would be nice.

The function is chdir, not cd.  The 'cd' man page says that 'cd -P' should "perform actions equivalent to the chdir() function".

So, you are asking for a different function, which should *not* be named 'os.chdir'.  You'll have to make a case for it being useful enough to add.

The same applies to getcwd, which is also a wrapper for the posix function, not an emulation of the shell's pwd.

'cd' is not an external command and has no manpage. It is a shell builtin command.

Most os functions are thin wrappers around system calls. There is no system call that works as 'cd' without '-P'.

If you implement a shell in Python, you perhaps need an implementation of the 'cd' command. But I have doubts that this is needed in the stdlib.

Thanks for the additional information!

> The 'cd' man page says that 'cd -P' should "perform actions equivalent to the chdir() function".

Just wondering, do you know what is the function called by `cd`/`cd -L` then? It doesn't seems to be a bash internal tweak because `/usr/bin/pwd -L` is able to get the symlink path, and this binary is not part of bash.

> You'll have to make a case for it being useful enough to add.

The use case is for shells written in Python, like for instance `xonsh` [1,2]. Being powered by Python, the only way to change directory is by using `os.chdir()`. It is then not possible to mimic the bash `cd` function without using workarounds, like for instance storing the symlink path in a variable, and even this doesn't allow to use `/usr/bin/pwd -L` in scripts because it would always returns the physical location.

Having such described functions (yet to be named) would permit python shells to offer users differentiated `cd` and `cd -P` commands, as well as having `pwd -L` in scripts behaving the same than in traditional shells.

[1] http://xon.sh/
[2] https://github.com/xonsh/xonsh

Since yours is the itch, I'm afraid you are going to have to be the one to figure out how this could be implemented :)

> Most os functions are thin wrappers around system calls. There is no system call that works as 'cd' without '-P'.

I would like to believe in this, but then if `cd` is some bash internal, how does `/usr/bin/pwd -L` find it back?

> Since yours is the itch, I'm afraid you are going to have to be the one to figure out how this could be implemented :)

Once I'll have figured out how all this is working, maybe. Not sure it would me in my competencies though.

> Just wondering, do you know what is the function called by `cd`/`cd -L` then? It doesn't seems to be a bash internal tweak because `/usr/bin/pwd -L` is able to get the symlink path, and this binary is not part of bash.

See shells sources. According to the manpage `pwd -L` just uses PWD from environment.

Ah, that should all be implementable from your python shell, then, no need for support in the os module.

For reference, when I said 'cd man page', this is what I was referring to:

http://www.unix.com/man-page/posix/1posix/cd/

I'm going to close this issue.  If you find you do need access to some system interface the os module doesn't currently provide, you can open a specific issue for that.

> I'm going to close this issue. 

I was doing to do so, here was my message:

--------------------------------------------

> See shells sources. According to the manpage `pwd -L` just uses PWD from environment.

I looked directly at `pwd` sources, and indeed it is using $PWD [1].

[1] http://git.savannah.gnu.org/cgit/coreutils.git/tree/src/pwd.c?id=509152bdd47a278dc00ddaf3200ac65044b836b1#n305

So it looks like `cd -L` is just some bash internal dealing with $PWD. Probably not something useful enough to be in the standard library, closing it then.

Sorry for the incovenience