ubuntu升级pip后， ImportError: cannot import name ‘main‘

场景描述：

原先pip安装完成之后，一直没有更新版本，原pip版本为8.1.1，今天安装python 包pysftp的时候，提示需要升级pip到（pip 10.0.1）;

于是乎，直接手到擒来，终端命令行执行：

$ sudo pip install --upgrade pip

升级完成之后，查看版本pip --version 显示：pip 10.0.1

之后安装sudo pip install pysftp

提示：

ImportError: cannot import name ‘main‘

啥问题呀，百度？！！！

https://www.cnblogs.com/white-the-Alan/p/8900554.html

改完之后没有效果！啥子原因！囧，我特发！

原因分析：

1. 提示报错为：/user/bin/pip第九行有问题

2. which pip

/home/odoo/.local/bin/pip

搜嘎，原来更新升级之后的pip安装路径变了，没有更新/user/bin下的配置，导致我们运行pip命令的时候，执行的还是原先就的程序。我们知道/user/bin目录下的程序，基本为程序包安装时候创建的软链接！！！

知道问题原因后，就知道如何处理了。

解决方式：

两种，第一种删除旧的/user/bin下的pip软链接，重新设置。

方式二，直接卸载原有pip重新安装，指定软链接为新的路径。

这里采用的第二种，重装前先卸载ubuntu的pip包
sudo apt-get remove python-pip

重新安装：sudo apt-get install python-pip python-dev build-essential

odoo@test:/usr/bin$ sudo apt-get install python-pip python-dev build-essential
Reading package lists... Done
Building dependency tree
Reading state information... Done
build-essential is already the newest version (.1ubuntu2).
python-dev is already the newest version (2.7.-~16.04).
python-dev set to manually installed.
The following packages were automatically installed and are no longer required:
  linux-headers-4.13.- linux-headers-4.13.--generic
  linux-headers-4.13.- linux-headers-4.13.--generic
  linux-image-4.13.--generic linux-image-4.13.--generic
  linux-image-extra-4.13.--generic linux-image-extra-4.13.--generic
Use 'sudo apt autoremove' to remove them.
The following NEW packages will be installed:
  python-pip
 upgraded,  newly installed,  to remove and  not upgraded.
Need to get  kB of archives.
After this operation,  kB of additional disk space will be used.
Do you want to continue? [Y/n] y
Get: http://cn.archive.ubuntu.com/ubuntu xenial-updates/universe amd64 python-pip all 8.1.1-2ubuntu0.4 [144 kB]
Fetched  kB in 1s (94.4 kB/s)
Selecting previously unselected package python-pip.
(Reading database ...  files and directories currently installed.)
Preparing to unpack .../python-pip_8.1.1-2ubuntu0.4_all.deb ...
Unpacking python-pip (8.1.-2ubuntu0.) ...
Processing triggers for man-db (2.7.-) ...
Setting up python-pip (8.1.-2ubuntu0.) ...

odoo@test:/usr/bin$
odoo@test:/usr/bin$ pip --version
pip 10.0. from /home/odoo/.local/lib/python2./site-packages/pip (python 2.7)

创建软链接：

sudo ln -s /usr/local/bin/pip /usr/bin/pip

pip --version
pip 10.0. from /usr/local/lib/python2./dist-packages/pip-10.0.-py2..egg/pip (python 2.7)

安装pysftp 这里切换在root用户下安装了，普通用户的话需要加sudo pip install pysftp

root@odoo-test:/usr/local/bin# pip install pysftp
Collecting pysftp
  Downloading https://files.pythonhosted.org/packages/36/60/45f30390a38b1f92e0a8cf4de178cd7c2bc3f874c85430e40ccf99df8fe7/pysftp-0.2.9.tar.gz
Collecting paramiko>=1.17 (from pysftp)
  Downloading https://files.pythonhosted.org/packages/3e/db/cb7b6656e0e7387637ce850689084dc0b94b44df31cc52e5fc5c2c4fd2c1/paramiko-2.4.1-py2.py3-none-any.whl (194kB)
    % |████████████████████████████████| 194kB .8kB/s
Requirement already satisfied: pyasn1>=0.1. in /usr/lib/python2./dist-packages (from paramiko>=1.17->pysftp) (0.1.)
Collecting bcrypt>=3.1. (from paramiko>=1.17->pysftp)
  Downloading https://files.pythonhosted.org/packages/2e/5a/2abeae20ce294fe6bf63da0e0b5a885c788e1360bbd124edcc0429678a59/bcrypt-3.1.4-cp27-cp27mu-manylinux1_x86_64.whl (57kB)
    % |████████████████████████████████| 61kB .0kB/s
Collecting cryptography>=1.5 (from paramiko>=1.17->pysftp)
  Downloading https://files.pythonhosted.org/packages/dd/c2/3a5bfefb25690725824ade71e6b65449f0a9f4b29702cce10560f786ebf6/cryptography-2.2.2-cp27-cp27mu-manylinux1_x86_64.whl (2.2MB)
    % |████████████████████████████████| .2MB 22kB/s
Collecting pynacl>=1.0. (from paramiko>=1.17->pysftp)
  Downloading https://files.pythonhosted.org/packages/80/3d/d709b9fbd69e21dd3a4d34eb690c5484094699e03b7447bc7eb173cfd7b6/PyNaCl-1.2.1-cp27-cp27mu-manylinux1_x86_64.whl (696kB)
    % |████████████████████████████████| 706kB .5kB/s
Requirement already satisfied: six>=1.4. in /usr/lib/python2./dist-packages (from bcrypt>=3.1.->paramiko>=1.17->pysftp) (1.10.)
Collecting cffi>=1.1 (from bcrypt>=3.1.->paramiko>=1.17->pysftp)
  Downloading https://files.pythonhosted.org/packages/14/dd/3e7a1e1280e7d767bd3fa15791759c91ec19058ebe31217fe66f3e9a8c49/cffi-1.11.5-cp27-cp27mu-manylinux1_x86_64.whl (407kB)
    % |████████████████████████████████| 409kB .7kB/s
Requirement already satisfied: enum34; python_version < "" in /usr/lib/python2./dist-packages (from cryptography>=1.5->paramiko>=1.17->pysftp) (1.1.)
Collecting asn1crypto>=0.21. (from cryptography>=1.5->paramiko>=1.17->pysftp)
  Downloading https://files.pythonhosted.org/packages/ea/cd/35485615f45f30a510576f1a56d1e0a7ad7bd8ab5ed7cdc600ef7cd06222/asn1crypto-0.24.0-py2.py3-none-any.whl (101kB)
    % |████████████████████████████████| 102kB .0kB/s
Collecting idna>=2.1 (from cryptography>=1.5->paramiko>=1.17->pysftp)
  Downloading https://files.pythonhosted.org/packages/27/cc/6dd9a3869f15c2edfab863b992838277279ce92663d334df9ecf5106f5c6/idna-2.6-py2.py3-none-any.whl (56kB)
    % |████████████████████████████████| 61kB .9kB/s
Requirement already satisfied: ipaddress; python_version < "" in /usr/lib/python2./dist-packages (from cryptography>=1.5->paramiko>=1.17->pysftp) (1.0.)
Collecting pycparser (from cffi>=1.1->bcrypt>=3.1.->paramiko>=1.17->pysftp)
  Downloading https://files.pythonhosted.org/packages/8c/2d/aad7f16146f4197a11f8e91fb81df177adcc2073d36a17b1491fd09df6ed/pycparser-2.18.tar.gz (245kB)
    % |████████████████████████████████| 256kB .4kB/s
Building wheels for collected packages: pysftp, pycparser
  Running setup.py bdist_wheel for pysftp ... done
  Stored in directory: /root/.cache/pip/wheels/d4///181ea4f6c795b40c4f1d2022ba2ed15cf811d22975eb2e5968
  Running setup.py bdist_wheel for pycparser ... done
  Stored in directory: /root/.cache/pip/wheels/c0/a1//5ba234bd77ea5a290cbf6d675259ec52293193467a12ef1f46
Successfully built pysftp pycparser
Installing collected packages: pycparser, cffi, bcrypt, asn1crypto, idna, cryptography, pynacl, paramiko, pysftp
  Found existing installation: idna 2.0
    Uninstalling idna-2.0:
      Successfully uninstalled idna-2.0
  Found existing installation: cryptography 1.2.
    Uninstalling cryptography-1.2.:
      Successfully uninstalled cryptography-1.2.
Successfully installed asn1crypto-0.24. bcrypt-3.1. cffi-1.11. cryptography-2.2. idna-2.6 paramiko-2.4. pycparser-2.18 pynacl-1.2. pysftp-0.2.

OK !