所以我在rasberry pi上使用python 2.7并且我正在尝试安装virtualenv。所以当我输入：
$ sudo pip install virtualenv virtualenvwrapper
我收到这条很长的错误消息：
Exception:
Traceback (most recent call last):
File "/usr/lib/python2.7/dist-packages/pip/basecommand.py", line 215, in main status = self.run(options, args)
File "/usr/lib/python2.7/dist-packages/pip/commands/install.py", line 353, in run wb.build(autobuilding=True)
File "/usr/lib/python2.7/dist-packages/pip/wheel.py", line 749, in build self.requirement_set.prepare_files(self.finder)
File "/usr/lib/python2.7/dist-packages/pip/req/req_set.py", line 380, in prepare_files ignore_dependencies=self.ignore_dependencies))
File "/usr/lib/python2.7/dist-packages/pip/req/req_set.py", line 620, in _prepare_file
session=self.session, hashes=hashes)
File "/usr/lib/python2.7/dist-packages/pip/download.py", line 821, in unpack_url
hashes=hashes
File "/usr/lib/python2.7/dist-packages/pip/download.py", line 659, in unpack_http_url
hashes)
File "/usr/lib/python2.7/dist-packages/pip/download.py", line 853, in _download_http_url
stream=True,
File "/usr/share/python-wheels/requests-2.12.4-py2.py3-none-any.whl/requests/sessions.py", line 501, in get
return self.request('GET', url, **kwargs)
File "/usr/lib/python2.7/dist-packages/pip/download.py", line 386, in request
return super(PipSession, self).request(method, url, *args, **kwargs)
File "/usr/share/python-wheels/requests-2.12.4-py2.py3-none-any.whl/requests/sessions.py", line 488, in request
resp = self.send(prep, **send_kwargs)
File "/usr/share/python-wheels/requests-2.12.4-py2.py3-none-any.whl/requests/sessions.py", line 609, in send
r = adapter.send(request, **kwargs)
File "/usr/share/python-wheels/CacheControl-0.11.7-py2.py3-none-any.whl/cachecontrol/adapter.py", line 47, in send
resp = super(CacheControlAdapter, self).send(request, **kw)
File "/usr/share/python-wheels/requests-2.12.4-py2.py3-none-any.whl/requests/adapters.py", line 497, in send
raise SSLError(e, request=request)
SSLError: ("bad handshake: Error([('SSL routines', 'tls_process_server_certificate', 'certificate verify failed')],)",)
我也尝试升级pip，因为它已经过时了，但遇到了类似的错误。
我所使用的版本是9.0.1。我环顾了很多论坛，但无法弄清楚这意味着什么，或者如何解决它。