/root/.python-eggs 报错

部署过程中，使用虚环境，但是启动程序的时候报错，如下：

Traceback (most recent call last):
  File "/home/himalayas/fdsearch/fdsearch/bin/fdsearch", line 34, in <module>
    from fdsearch import wsgi
  File "/home/himalayas/fdsearch/fdsearch/wsgi.py", line 32, in <module>
    import fdsearch.domain
  File "/home/himalayas/fdsearch/fdsearch/domain/__init__.py", line 20, in <module>
    from notify_handler import NotifyHandler
  File "/home/himalayas/fdsearch/fdsearch/domain/notify_handler.py", line 23, in <module>
    from cjson import encode as json_encode
  File "build/bdist.linux-x86_64/egg/cjson.py", line 7, in <module>
  File "build/bdist.linux-x86_64/egg/cjson.py", line 4, in __bootstrap__
  File "/home/himalayas/virtualenv/python2.7-fd/lib/python2.7/site-packages/pkg_resources.py", line 945, in resource_filename
    self, resource_name
  File "/home/himalayas/virtualenv/python2.7-fd/lib/python2.7/site-packages/pkg_resources.py", line 1633, in get_resource_filename
    self._extract_resource(manager, self._eager_to_zip(name))
  File "/home/himalayas/virtualenv/python2.7-fd/lib/python2.7/site-packages/pkg_resources.py", line 1661, in _extract_resource
    self.egg_name, self._parts(zip_path)
  File "/home/himalayas/virtualenv/python2.7-fd/lib/python2.7/site-packages/pkg_resources.py", line 1025, in get_cache_path
    self.extraction_error()
  File "/home/himalayas/virtualenv/python2.7-fd/lib/python2.7/site-packages/pkg_resources.py", line 991, in extraction_error
    raise err
pkg_resources.ExtractionError: Can't extract file(s) to egg cache

The following error occurred while trying to extract file(s) to the Python egg
cache:

  [Errno 13] Permission denied: '/root/.python-eggs'

The Python egg cache directory is currently set to:

  /root/.python-eggs

解决办法：让开发在代码中声明一下环境变量。

export PYTHON_EGG_CACHE=/some/other/dir

注意：在系统的/etc/profile中声明是没有办法的，因为程序是在虚环境中运行。