Question

I am using:

Windows XP
Python 2.6.2 (standard install from python.org)
git version 1.6.5.1-preview20091022 (installed from http://code.google.com/p/msysgit/)

I have an environment variable looking like an absolute path (/path/to/dir) but I m using it to construct a git URL. At some point, it s getting translated to C:/Program Files/Git/path/to/dir. It seems like Python is at fault:

In a git bash shell:

$ export VAR=/path/to/dir
$ echo $VAR
/path/to/dir
$ python
>>> import os
>>> os.environ[ VAR ]
 C:/Program Files/Git/path/to/dir

git bash is not translating the path, but Python is?

In a Windows Command Prompt, Python gets it right:

C:>set VAR=/path/to/dir
C:>echo %VAR%
/path/to/dir

C:>python
>>> import os
>>> os.environ[ VAR ]
 /path/to/dir

Can anyone explain what s going on here? And how can I prevent the translation in a bash shell?

EDIT: I should add that my python script runs on OS X and Windows, so if anyone does have a solution it would be good if worked on both platforms.

Answer 1

My guess would be that this is not python at fault, but the git bash shell.
Maybe the git bash shell is lying to you when you look at the variable.
Or, try to not put the first / and add it again later (if translation does not occurs).

If I try with cygwin, it works:

$ export test="/bin"
$ python
>>> import os
>>> os.environ["test"]
 /bin

Answer 2

The problem definitely sounds like it s caused by MSYS. When an MSYS process execs a non-MSYS process (e.g. your msysgit bash shell calling native Windows Python), the arguments are checked for anything that looks like an absolute POSIX path (e.g. things that start with a single / ) and these are translated to the underlying real Windows path so that the non-MSYS program can find them. It s likely that this same process happens to the contents of your environment variables too, for the same reason.

This would be why removing the leading / works (the value doesn t look like a POSIX path any more), why adding an extra one works (ditto), and why this works fine under Cygwin (it s not MSYS). I m also guessing that you installed msysgit at C:Program FilesGit , and that this is why MSYS thinks its fake POSIX file hierarchy is rooted there and adds it to the front of /path/to/dir for you.

Unfortunately, if that is the explanation then there isn t a clear solution. I hit a similar issue trying to pass remote paths through ssh and haven t found any good ways round this myself, and according to the discussion at http://comments.gmane.org/gmane.comp.gnu.mingw.msys/4511 (from 2008) there simply isn t an obvious fix beyond the workarounds you ve found so far. If this turns into a bigger problem for you, you might want to raise it on the MinGW-MSYS mailing lists or bug tracker. According to the Gmane discussion, it had never been reported formally despite being a known issue.

Answer 3

The console you get from msysgit is probably modified for git user s needs, from my POV, it is only useful for simple tasks and to access git command line not to develop and run python scripts (you are using a Python installation for Windows in a shell installed for a specific application, that doesn t sound good).

You should install Cygwin and his python package (and even git package if you want) to get a correct POSIX environment with binaries and libraries prepared for it.

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