我在 OS X Yosemite 10.10.5 上安装了 Python 2.7。我想通过 PIP 安装 NPM，命令显示成功，我在 /Library/Python/2.7/site-packages/ 中有一个名为 npm 的目录，但是使用 NPM 执行任何操作都会产生“找不到命令”。
这是我安装 PIP 和 NPM 的方式：
第1步
sudo easy_install pip
将此作为输出：
Reading https://pypi.python.org/simple/pip/
Best match: pip 8.1.2
Downloading https://pypi.python.org/packages/e7/a8/7556133689add8d1a54c0b14aeff0acb03c64707ce100ecd53934da1aa13/pip-8.1.2.tar.gz#md5=87083c0b9867963b29f7aba3613e8f4a
Processing pip-8.1.2.tar.gz
Writing /tmp/easy_install-v4g_ZO/pip-8.1.2/setup.cfg
Running pip-8.1.2/setup.py -q bdist_egg --dist-dir /tmp/easy_install-v4g_ZO/pip-8.1.2/egg-dist-tmp-5Ku7Ds
warning: no previously-included files found matching '.coveragerc'
warning: no previously-included files found matching '.mailmap'
warning: no previously-included files found matching '.travis.yml'
warning: no previously-included files found matching '.landscape.yml'
warning: no previously-included files found matching 'pip/_vendor/Makefile' …