在阿里云服务器上，用virtualenv创建虚拟环境时，报了个错误
root@iZwz982qla1uxm1s5dnyo7Z:/usr/lib/python3/dist-packages/virtualenv-15.0.1.egg-info# virtualenv -p python3 venv Running virtualenv with interpreter /usr/bin/python2 New python executable in /usr/lib/python3/dist-packages/virtualenv-15.0.1.egg-info/venv/bin/python2 Not overwriting existing python script /usr/lib/python3/dist-packages/virtualenv-15.0.1.egg-info/venv/bin/python (you must use /usr/lib/python3/dist-packages/virtualenv-15.0.1.egg-info/venv/bin/python2) Please make sure you remove any previous custom paths from your /root/.pydistutils.cfg file. 1 [global] Installing setuptools, pkg_resources, pip, wheel... Complete output from command /usr/lib/python3/dis...nfo/venv/bin/python2 - setuptools pkg_resources pip wheel: Collecting setuptools Downloading http://mirrors.aliyun.com/pypi/packages/ff/f4/385715ccc461885f3cedf57a41ae3c12b5fec3f35cce4c8706b1a112a133/setuptools-40.0.0-py2.py3-none-any.whl (567kB) Collecting pkg_resources Exception: Traceback (most recent call last): File "/usr/share/python-wheels/pip-8.1.1-py2.py3-none-any.whl/pip/basecommand.py", line 209, in main status = self.run(options, args) File "/usr/share/python-wheels/pip-8.1.1-py2.py3-none-any.whl/pip/commands/install.py", line 328, in run wb.build(autobuilding=True) File "/usr/share/python-wheels/pip-8.1.1-py2.py3-none-any.whl/pip/wheel.py", line 748, in build self.requirement_set.prepare_files(self.finder) File "/usr/share/python-wheels/pip-8.1.1-py2.py3-none-any.whl/pip/req/req_set.py", line 360, in prepare_files ignore_dependencies=self.ignore_dependencies)) File "/usr/share/python-wheels/pip-8.1.1-py2.py3-none-any.whl/pip/req/req_set.py", line 512, in _prepare_file finder, self.upgrade, require_hashes) File "/usr/share/python-wheels/pip-8.1.1-py2.py3-none-any.whl/pip/req/req_install.py", line 273, in populate_link self.link = finder.find_requirement(self, upgrade) File "/usr/share/python-wheels/pip-8.1.1-py2.py3-none-any.whl/pip/index.py", line 442, in find_requirement all_candidates = self.find_all_candidates(req.name) File "/usr/share/python-wheels/pip-8.1.1-py2.py3-none-any.whl/pip/index.py", line 400, in find_all_candidates for page in self._get_pages(url_locations, project_name): File "/usr/share/python-wheels/pip-8.1.1-py2.py3-none-any.whl/pip/index.py", line 545, in _get_pages page = self._get_page(location) File "/usr/share/python-wheels/pip-8.1.1-py2.py3-none-any.whl/pip/index.py", line 648, in _get_page return HTMLPage.get_page(link, session=self.session) File "/usr/share/python-wheels/pip-8.1.1-py2.py3-none-any.whl/pip/index.py", line 760, in get_page resp.raise_for_status() File "/usr/lib/python3/dist-packages/virtualenv-15.0.1.egg-info/venv/share/python-wheels/requests-2.9.1-py2.py3-none-any.whl/requests/models.py", line 840, in raise_for_status raise HTTPError(http_error_msg, response=self) HTTPError: 404 Client Error: Not Found for url: http://mirrors.aliyun.com/pypi/simple/pkg-resources/ ---------------------------------------- ...Installing setuptools, pkg_resources, pip, wheel...done. Traceback (most recent call last): File "/usr/lib/python3/dist-packages/virtualenv.py", line 2363, in <module> main() File "/usr/lib/python3/dist-packages/virtualenv.py", line 719, in main symlink=options.symlink) File "/usr/lib/python3/dist-packages/virtualenv.py", line 988, in create_environment download=download, File "/usr/lib/python3/dist-packages/virtualenv.py", line 918, in install_wheel call_subprocess(cmd, show_stdout=False, extra_env=env, stdin=SCRIPT) File "/usr/lib/python3/dist-packages/virtualenv.py", line 812, in call_subprocess % (cmd_desc, proc.returncode)) OSError: Command /usr/lib/python3/dis...nfo/venv/bin/python2 - setuptools pkg_resources pip wheel failed with error code 2
看到HTTPError: 404 Client Error: Not Found for url: http://mirrors.aliyun.com/pypi/simple/pkg-resources/以为是阿里云的安全组配置没配好，折腾了半天，原来是访问PyPI镜像源出了问题，将pip的默认的源地址改为国内源即可。
具体操作如下：
vim ~/.pip/pip.conf打开pip配置文件:
写入
[global] index-url = http://e.pypi.python.org/simple
以下这几个国内源都可以
e.pypi.python.org
pypi.douban.com
pypi.hustunique.com
补充：使用virtualenv创建Python3.7虚拟环境时报错ModuleNotFoundError: No module named '_ctypes'的解决方法
使用virtualenv创建Python3.7.6版本虚拟环境时，遇到了标题中的报错，记录一下解决过程。
出现这种情况一般是因为缺少依赖包libffi-devel
在安装3.7以上版本时，需要一个新的libffi-devel包做依赖
使用yum安装依赖
yum install libffi-devel -y
删除之前安装的报错的虚拟环境目录
rm -f venv
重新编译安装系统Python3.7.6（需要先找到安装时的Python源码包，cd到目录中）
./configure --prefix=/usr/local/python3 make && make install
删除之前建立的软连接
rm -rf /usr/bin/python3 rm -rf /usr/bin/pip3
重新建立软连接
ln -s /usr/local/python3/bin/python3.7 /usr/bin/python3 ln -s /usr/local/python3/bin/pip3.7 /usr/bin/pip3
到此Python3重新安装完成，可以用python3、pip3命令测试一下是否安装成功。
进入虚拟目录将要存放的目录，使用新安装的Python3创建虚拟环境。此处需要使用-p参数指定Python版本路径，否则默认创建Python2的环境。
virtualenv -p /usr/bin/python3 venv
测试进入创建好的虚拟环境中
source venv/bin/activate
退出环境
deactivate
以上为个人经验，希望能给大家一个参考，也希望大家多多支持。如有错误或未考虑完全的地方，望不吝赐教。
