title: Why is it "pip2" instead of "pip" after installed python with brew?
body: <p>I ran <code>brew install python</code> on my mac 10.12.3, and the logs are as following:</p>
  
  <pre><code>==&gt; Summary
    /usr/local/Cellar/sqlite/3.20.1: 11 files, 3.0MB
  ==&gt; Installing python
  ==&gt; Downloading https://homebrew.bintray.com/bottles/python-2.7.13_1.sierra.bottle.tar.gz
  ######################################################################## 100.0%
  ==&gt; Pouring python-2.7.13_1.sierra.bottle.tar.gz
  ==&gt; /usr/local/Cellar/python/2.7.13_1/bin/python2 -s setup.py --no-user-cfg install --force --verbose --single-
  ==&gt; /usr/local/Cellar/python/2.7.13_1/bin/python2 -s setup.py --no-user-cfg install --force --verbose --single-
  ==&gt; /usr/local/Cellar/python/2.7.13_1/bin/python2 -s setup.py --no-user-cfg install --force --verbose --single-
  ==&gt; Caveats
  This formula installs a python2 executable to /usr/local/bin.
  If you wish to have this formula's python executable in your PATH then add
  the following to ~/.bash_profile:
    export PATH="/usr/local/opt/python/libexec/bin:$PATH"
  
  Pip and setuptools have been installed. To update them
    pip2 install --upgrade pip setuptools
  
  You can install Python packages with
    pip2 install &lt;package&gt;
  
  They will install into the site-package directory
    /usr/local/lib/python2.7/site-packages
  
  See: https://docs.brew.sh/Homebrew-and-Python.html
  ==&gt; Summary
  </code></pre>
  
  <p>```</p>
  
  <p>As the log said, we have the pip2 command other than pip. How should these happen?</p>