title: GNU grep line buffered not working on MacOS
body: <p>I am trying to grep the output from a continuously running program, on Linux I just used --line-buffered, but it is not working on macOS and I am at a loss as to what to try next. </p>
  
  <pre><code>macbook:~$ ggrep --version
  ggrep (GNU grep) 3.3
  Packaged by Homebrew
  Copyright (C) 2018 Free Software Foundation, Inc.
  License GPLv3+: GNU GPL version 3 or later &lt;https://gnu.org/licenses/gpl.html&gt;.
  This is free software: you are free to change and redistribute it.
  There is NO WARRANTY, to the extent permitted by law.
  
  Written by Mike Haertel and others; see
  &lt;https://git.sv.gnu.org/cgit/grep.git/tree/AUTHORS&gt;.
  macbook:~$ adb logcat | ggrep --line-buffered e
  
    &lt;no output until I ctrl-C&gt;
  </code></pre>