pip是python的包管理工具，准备写爬虫所以安装下。
Step1.brew install pip(不能下载)
Updating Homebrew...
==> Auto-updated Homebrew!
Updated 1 tap (homebrew/core).
==> Updated Formulae
couchdb dcos-cli fobis kube-aws libpng m-cli mmark thefuck vips
Error: Could not link:
/usr/local/share/doc/homebrew
Please delete these paths and run `brew update`.
==> Migrating HOMEBREW_REPOSITORY (please wait)...
Error: /usr/local/Homebrew already exists.
Please remove it manually or uninstall and reinstall Homebrew into a new
location as the migration cannot be done automatically.
Error: No available formula with the name "pip"
Homebrew provides pip via: `brew install python`. However you will then
have two Pythons installed on your Mac, so alternatively you can install
pip via the instructions at:
https://pip.readthedocs.io/en/stable/installing/
可以看出pip是跟着python一起安装的。
Step2.使用easy_install 安装pip
由于我当前的python版本是mac自带的2.7.10，所以找到easy_install 安装pip:
sudo python /usr/bin/easy_install-2.7 pip
