linux ubuntu 16.04 python3.5 cuda9重装pip以及安装【指定版本】pytorch

 pip报错1：

$ sudo -H pip3 --proxy=xx.xxx.xx.xxx --trusted-host pypi.org --trusted-host pytorch.org --trusted-host pythonhosted.org install torch==0.4.1 torchvision==0.2.2.post3 -f https://download.pytorch.org/whl/torch_stable.html
Looking in indexes: https://files.pythonhosted.org
Looking in links: https://download.pytorch.org/whl/torch_stable.html
Collecting torch==0.4.1
  WARNING: Retrying (Retry(total=4, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ProxyError('Cannot connect to proxy.', OSError('Tunnel connection failed: 400 Bad Request',))': /torch/
  WARNING: Retrying (Retry(total=3, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ProxyError('Cannot connect to proxy.', OSError('Tunnel connection failed: 400 Bad Request',))': /torch/

原因：代理设置有误，没写端口名

pip报错2：

$ pip3 --trusted-host pypi.org --trusted-host pytorch.org --proxy=xx.xxx.xx.xxx:8080 install torch==0.4.1 torchvision==0.2.2.post3 -f https://download.pytorch.org/whl/torch_stable.html
Looking in links: https://download.pytorch.org/whl/torch_stable.html
Collecting torch==0.4.1
  WARNING: Retrying (Retry(total=4, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError(SSLError(1, '[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:645)'),)': /whl/torch_stable.html
  WARNING: Retrying (Retry(total=3, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError(SSLError(1, '[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:645)'),)': /whl/torch_stable.html
  WARNING: Retrying (Retry(total=2, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError(SSLError(1, '[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:645)'),)': /whl/torch_stable.html
  WARNING: Retrying (Retry(total=1, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError(SSLError(1, '[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:645)'),)': /whl/torch_stable.html
  WARNING: Retrying (Retry(total=0, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError(SSLError(1, '[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:645)'),)': /whl/torch_stable.html
  Could not fetch URL https://download.pytorch.org/whl/torch_stable.html: There was a problem confirming the ssl certificate: HTTPSConnectionPool(host='download.pytorch.org', port=443): Max retries exceeded with url: /whl/torch_stable.html (Caused by SSLError(SSLError(1, '[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:645)'),)) - skipping
  WARNING: Retrying (Retry(total=4, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError(SSLError(1, '[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:645)'),)': /packages/f9/4e/1bcb4688b7506c340ca6ba5b9f57f4ad3b59a193bba365bf2b51e9e4bb3e/torch-0.4.1-cp35-cp35m-manylinux1_x86_64.whl
  WARNING: Retrying (Retry(total=3, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError(SSLError(1, '[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:645)'),)': /packages/f9/4e/1bcb4688b7506c340ca6ba5b9f57f4ad3b59a193bba365bf2b51e9e4bb3e/torch-0.4.1-cp35-cp35m-manylinux1_x86_64.whl
  WARNING: Retrying (Retry(total=2, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError(SSLError(1, '[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:645)'),)': /packages/f9/4e/1bcb4688b7506c340ca6ba5b9f57f4ad3b59a193bba365bf2b51e9e4bb3e/torch-0.4.1-cp35-cp35m-manylinux1_x86_64.whl
  WARNING: Retrying (Retry(total=1, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError(SSLError(1, '[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:645)'),)': /packages/f9/4e/1bcb4688b7506c340ca6ba5b9f57f4ad3b59a193bba365bf2b51e9e4bb3e/torch-0.4.1-cp35-cp35m-manylinux1_x86_64.whl
  WARNING: Retrying (Retry(total=0, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError(SSLError(1, '[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:645)'),)': /packages/f9/4e/1bcb4688b7506c340ca6ba5b9f57f4ad3b59a193bba365bf2b51e9e4bb3e/torch-0.4.1-cp35-cp35m-manylinux1_x86_64.whl
ERROR: Could not install packages due to an EnvironmentError: HTTPSConnectionPool(host='files.pythonhosted.org', port=443): Max retries exceeded with url: /packages/f9/4e/1bcb4688b7506c340ca6ba5b9f57f4ad3b59a193bba365bf2b51e9e4bb3e/torch-0.4.1-cp35-cp35m-manylinux1_x86_64.whl (Caused by SSLError(SSLError(1, '[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:645)'),))

原因：命令语法不对。修改命令，参考下文。 

# 卸载Pip
$ sudo -H pip uninstall pip
$ sudo apt-get remove python-pip

# 下载pip
# 文件地址在官网：https://pypi.org/project/pip/#files
$ wget --no-check-certificate https://files.pythonhosted.org/packages/00/9e/4c83a0950d8bdec0b4ca72afd2f9cea92d08eb7c1a768363f2ea458d08b4/pip-19.2.3.tar.gz

# 安装pip
$ tar -zxvf pip-19.2.3.tar.gz
$ cd pip-19.2.3/
$ sudo python3 setup.py install

# 更新pip
$ sudo -H pip3 --proxy=xx.xxx.xx.xxx:8080 --trusted-host pypi.org --trusted-host files.pythonhosted.org install --upgrade pip

# 输出：
# Looking in indexes: https://files.pythonhosted.org
# Requirement already up-to-date: pip in /usr/local/lib/python3.5/dist-packages/pip-19.2.3-# py3.5.egg (19.2.3)

# 安装torch
$ pip install --upgrade pip --trusted-host pypi.org --trusted-host files.pythonhosted.org torch==0.4.1

# 安装torchvision
$ pip install --trusted-host pypi.org --trusted-host files.pythonhosted.org torchvision==0.2.2.post3