“pip install json” fails on Ubuntu

问题:

Cannot install the json module. As far as I know I shouldn't use sudo. what's the matter?

 pip install json
The directory '/home/snow/.cache/pip/http' or its parent directory is not owned by the current user and the cache has been disabled. Please check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.
The directory '/home/snow/.cache/pip' or its parent directory is not owned by the current user and caching wheels has been disabled. check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.
Collecting json
  Downloading json-99.0.tar.gz
    Complete output from command python setup.py egg_info:
    Traceback (most recent call last):
      File "<string>", line 1, in <module>
      File "/tmp/pip-build-YkvqVh/json/setup.py", line 2, in <module>
        raise RuntimeError("Package 'json' must not be downloaded from pypi")
    RuntimeError: Package 'json' must not be downloaded from pypi

    ----------------------------------------
Command "python setup.py egg_info" failed with error code 1 in /tmp/pip-build-YkvqVh/json/

回答1:

json is a built-in module, you don't need to install it with pip.

回答2:

While it's true that json is a built-in module, I also found that on an Ubuntu system with python-minimal installed, you DO have python but you can't do import json. And then I understand that you would try to install the module using pip!

If you have python-minimal you'll get a version of python with less modules than when you'd typically compile python yourself, and one of the modules you'll be missing is the json module. The solution is to install an additional package, called libpython2.7-stdlib, to install all 'default' python libraries.

sudo apt install libpython2.7-stdlib

And then you can do import json in python and it would work!