To use STDBUF from Homebrew's coreutils
coreutils on OS X adds the prefix g to all the commands so as to not mess up with default programs on OS X.

It prints this when you run brew install coreutils

==&gt; Caveats
All commands have been installed with the prefix 'g'.

If you really need to use these commands with their normal names, you
can add a "gnubin" directory to your PATH from your bashrc like:

    PATH="/usr/local/opt/coreutils/libexec/gnubin:$PATH"


So unless you really need to use it as stdbuf, there is no real reason to update your path, you can simply run gstdbuf instead:

$ gstdbuf --help                                                         
Usage: gstdbuf OPTION... COMMAND