python getcwd 與dirname_os.getcwd（）vs os.path.abspath（os.path.dirname（__ file__））

I am using the os module to have relative paths in my Django projects settings.py file. The variable SITE_ROOT is set to the current working directory of the settings.py file and then used to reference all of the static/media directories also located in that same directory.

Heres my issue:

print os.getcwd()

print os.path.abspath(os.path.dirname(__file__))

In settings.py, the above statements both have identical outputs. but my template will only load if I use SITE_ROOT = os.path.abspath(os.path.dirname(__file__))

Django looks for the templates here:

TEMPLATE_DIRS = (

os.path.join(SITE_ROOT, 'templates'),

)

SITE_ROOT set to os.getcwd() seems to make Django look for the templates folder in the directory ABOVE the settings.py file

I can just as easily not use os.getcwd() and my site runs fine, but I am curious what may be going on here :)

Anyone know?

解決方案

As mouad said, os.getcwd() won't give you exactly what you're expecting.

os.getcwd() does a bit more than returning the current working directory. It default to $PWD in your env. It's not where the script is located but where you were when you executed the script.

Being in /home/user and doing python manage.py, os.getcwd() will return /home/user

Being in /home/ and doing python user/manage.py, os.getcwd() will return /home

But it's still won't be always true since it's possible to use os.chdir(). It is in other word like doing cd. It will also change the return value of os.getcwd().

On the other hand. __file__ is the path of the module's file. So you have to use this to be certain to have a path relative to your module instead of the current working directory that may change.

As ShawnFumo said, __file__ might not be always absolute. To get a better idea on how it works, you can check that answer: Python __file__ attribute. Also, as of Python3.4 __file__ should always be an absolute path.

Hope it's clear.