报错代码：

WARNING: The directory '/Users/mac/Library/Caches/pip' or its parent directory is not owned or is not writable by the current user. The cache has been disabled. Check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.
Looking in indexes: http://pypi.douban.com/simple/
Collecting virtualenvwrapper
  Downloading http://pypi.doubanio.com/packages/c1/6b/2f05d73b2d2f2410b48b90d3783a0034c26afa534a4a95ad5f1178d61191/virtualenvwrapper-4.8.4.tar.gz (334 kB)
     |████████████████████████████████| 334 kB 4.7 MB/s 
    ERROR: Command errored out with exit status 1:
     command: /usr/local/opt/python/bin/python3.7 -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'/private/tmp/pip-install-7hgri4zv/virtualenvwrapper/setup.py'"'"'; __file__='"'"'/private/tmp/pip-install-7hgri4zv/virtualenvwrapper/setup.py'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(__file__);code=f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' egg_info --egg-base /private/tmp/pip-install-7hgri4zv/virtualenvwrapper/pip-egg-info
         cwd: /private/tmp/pip-install-7hgri4zv/virtualenvwrapper/
    Complete output (34 lines):
    WARNING: The directory '/Users/mac/Library/Caches/pip' or its parent directory is not owned or is not writable by the current user. The cache has been disabled. Check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.
    WARNING: The repository located at mirrors.aliyun.com is not a trusted or secure host and is being ignored. If this repository is available via HTTPS we recommend you use HTTPS instead, otherwise you may silence this warning and allow it anyway with '--trusted-host mirrors.aliyun.com'.
    ERROR: Could not find a version that satisfies the requirement pbr (from versions: none)
    ERROR: No matching distribution found for pbr
    Traceback (most recent call last):
      File "/usr/local/lib/python3.7/site-packages/setuptools/installer.py", line 128, in fetch_build_egg
        subprocess.check_call(cmd)
      File "/usr/local/Cellar/python/3.7.6_1/Frameworks/Python.framework/Versions/3.7/lib/python3.7/subprocess.py", line 363, in check_call
        raise CalledProcessError(retcode, cmd)
    subprocess.CalledProcessError: Command '['/usr/local/opt/python/bin/python3.7', '-m', 'pip', '--disable-pip-version-check', 'wheel', '--no-deps', '-w', '/tmp/tmpiow3p7p3', '--quiet', 'pbr']' returned non-zero exit status 1.
    
    During handling of the above exception, another exception occurred:
    
    Traceback (most recent call last):
      File "<string>", line 1, in <module>
      File "/private/tmp/pip-install-7hgri4zv/virtualenvwrapper/setup.py", line 7, in <module>
        pbr=True,
      File "/usr/local/lib/python3.7/site-packages/setuptools/__init__.py", line 144, in setup
        _install_setup_requires(attrs)
      File "/usr/local/lib/python3.7/site-packages/setuptools/__init__.py", line 139, in _install_setup_requires
        dist.fetch_build_eggs(dist.setup_requires)
      File "/usr/local/lib/python3.7/site-packages/setuptools/dist.py", line 721, in fetch_build_eggs
        replace_conflicting=True,
      File "/usr/local/lib/python3.7/site-packages/pkg_resources/__init__.py", line 783, in resolve
        replace_conflicting=replace_conflicting
      File "/usr/local/lib/python3.7/site-packages/pkg_resources/__init__.py", line 1066, in best_match
        return self.obtain(req, installer)
      File "/usr/local/lib/python3.7/site-packages/pkg_resources/__init__.py", line 1078, in obtain
        return installer(requirement)
      File "/usr/local/lib/python3.7/site-packages/setuptools/dist.py", line 777, in fetch_build_egg
        return fetch_build_egg(self, req)
      File "/usr/local/lib/python3.7/site-packages/setuptools/installer.py", line 130, in fetch_build_egg
        raise DistutilsError(str(e))
    distutils.errors.DistutilsError: Command '['/usr/local/opt/python/bin/python3.7', '-m', 'pip', '--disable-pip-version-check', 'wheel', '--no-deps', '-w', '/tmp/tmpiow3p7p3', '--quiet', 'pbr']' returned non-zero exit status 1.
    ----------------------------------------
ERROR: Command errored out with exit status 1: python setup.py egg_info Check the logs for full command output.

解决办法：

升级pip到最新

1、下载 get-pip.py

curl https://bootstrap.pypa.io/get-pip.py > /tmp/get-pip.py

2、执行升级pip

sudo python /tmp/get-pip.py

原文链接：https://www.jianshu.com/p/832245fc7276

再次安装报错：

You are using pip version 8.1.1, however version 18.0 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.

版本不一致导致，执行下面的语句解决

sudo python -m pip install --upgrade pip