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