Python：pip 尝试安装到 /bin 目录

我安装了 pythonbrew install python

which pip
/usr/local/bin/pip

my PYTHONPATH shows /usr/local/lib/python2.7/site-packages/

但是，当我尝试使用 pip 安装某些东西时，它会转到/bin/目录如下图。我想要安装的东西/usr/local/lib/python2.7/site-packages/。我该如何解决？

pip install virtualenv
Downloading/unpacking virtualenv
  Downloading virtualenv-1.11.6-py2.py3-none-any.whl (1.6MB): 1.6MB downloaded
Installing collected packages: virtualenv
Cleaning up...
Exception:
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/site-packages/pip-1.5.6-py2.7.egg/pip/basecommand.py", line 122, in main
    status = self.run(options, args)
  File "/usr/local/lib/python2.7/site-packages/pip-1.5.6-py2.7.egg/pip/commands/install.py", line 283, in run
{....}
  File "/usr/local/lib/python2.7/site-packages/pip-1.5.6-py2.7.egg/pip/_vendor/distlib/util.py", line 384, in write_binary_file
    with open(path, 'wb') as f:
IOError: [Errno 13] Permission denied: '/bin/virtualenv'



$ pip list
pip (1.5.6)
setuptools (5.4.2)
wsgiref (0.1.2)


$pip show setuptools
---
Name: setuptools
Version: 5.4.2
Location: /usr/local/lib/python2.7/site-packages/setuptools-5.4.2-py2.7.egg
Requires:

所以 pip 已经将基本包安装到了 site-packages 中。但是，运行相同的 pip 来安装 virtualenv 会尝试安装到 /bin/。

当我尝试安装 virtualenv 和 Flask 时，我遇到了同样的问题。原来我有一个.pydistutils.cfg文件在我的主目录中。我记得不久前把它放在那里作为安装其他东西的解决方法。一旦我删除了这个文件，运行pip install继续按预期工作。