__main__.ConfigurationError: Curl is configured to use SSL, but we have not been able to determine which SSL backend it is using. Please see PycURL documentation for how to specify the SSL backend man

　　今天在安装pyspider时遇到这个问题，显示是安装pycurl导致的，于是单独pip install pycurl，报一样的错误，如下：

(general_spider)  ~ � pip install pycurl
Collecting pycurl
  Using cached https://files.pythonhosted.org/packages/e8/e4/0dbb8735407189f00b33d84122b9be52c790c7c3b25286826f4e1bdb7bde/pycurl-7.43.0.2.tar.gz
    Complete output from command python setup.py egg_info:
    Using curl-config (libcurl 7.54.0)
    Traceback (most recent call last):
      File "<string>", line 1, in <module>
      File "/private/var/folders/rk/mmm98qtx6yjcr1dmtqqclq040000gn/T/pip-install-4G_Fpi/pycurl/setup.py", line 913, in <module>
        ext = get_extension(sys.argv, split_extension_source=split_extension_source)
      File "/private/var/folders/rk/mmm98qtx6yjcr1dmtqqclq040000gn/T/pip-install-4G_Fpi/pycurl/setup.py", line 582, in get_extension
        ext_config = ExtensionConfiguration(argv)
      File "/private/var/folders/rk/mmm98qtx6yjcr1dmtqqclq040000gn/T/pip-install-4G_Fpi/pycurl/setup.py", line 99, in __init__
        self.configure()
      File "/private/var/folders/rk/mmm98qtx6yjcr1dmtqqclq040000gn/T/pip-install-4G_Fpi/pycurl/setup.py", line 316, in configure_unix
        specify the SSL backend manually.''')
    __main__.ConfigurationError: Curl is configured to use SSL, but we have not been able to determine which SSL backend it is using. Please see PycURL documentation for how to specify the SSL backend manually.

    ----------------------------------------
Command "python setup.py egg_info" failed with error code 1 in /private/var/folders/rk/mmm98qtx6yjcr1dmtqqclq040000gn/T/pip-install-4G_Fpi/pycurl/

　　然后问题确定了，网上看看前辈们遇到这样的问题是怎样解决的：

Mac os解决方案（亲测有效问题已解决）：

 export PYCURL_SSL_LIBRARY=openssl
 export LDFLAGS=-L/usr/local/opt/openssl/lib;export CPPFLAGS=-I/usr/local/opt/openssl/include;

centos解决方案（楼主没有环境，需者自取，验证完可以告诉楼主一声～）：

export PYCURL_SSL_LIBRARY=openssl

　　执行完上述语句之后再执行 pip install pycurl，成功，皆大欢喜 进行后续操作就可以。

希望对你有帮助～

 参考地址：https://stackoverflow.com/questions/51019622/curl-is-configured-to-use-ssl-but-we-have-not-been-able-to-determine-which-ssl