Update Pip under ubuntu16.04

Using PIP Install–upgrade pip always complains ....
Uninstalling pip-7.1.0:
Exception:
Traceback (most recent call last):
File "/usr/lib/python3.5/shutil.py", line 538, in move
Os.rename (SRC, REAL_DST)
Permissionerror: [Errno] Permission denied: '/usr/local/lib/python3.5/dist-packages/pip-7.1.0-py3.5.egg '-> '/ Tmp/pip-whm8ys6u-uninstall/usr/local/lib/python3.5/dist-packages/pip-7.1.0-py3.5.egg '

attempting to update the PIP with the following command successfully solves the above problem
sudo python-m pip install–upgrade pip
The directory '/home/wang/.cache/pip/http ' or its parent directory isn't owned by the current user and the cache has been Disabled. Please check the permissions and owner of this directory. If executing pip with sudo, your may want sudo ' s-h flag.
You are are using PIP version 7.1.0, however version 9.0.1 is available.
You should consider upgrading via the ' pip install–upgrade Pip ' command.
The directory '/home/wang/.cache/pip/http ' or its parent directory isn't owned by the current user and the cache has been Disabled. Please check the permissions and owner of this directory. If executing pip with sudo, your may want sudo ' s-h flag.
Collecting Pip
Downloading PIP-9.0.1-PY2.PY3-NONE-ANY.WHL (1.3MB)
100% |████████████████████████████████| 1.3MB 127kb/s
Installing collected Packages:pip
Found existing Installation:pip 7.1.0
Uninstalling pip-7.1.0:
Successfully uninstalled pip-7.1.0
Successfully installed pip-9.0.1