Updating to Drush 7 on OSX
You should add to your ~/.bashrc file the additional PATH, e.g.:

# Add a Composer's global bin directory if exists.
which composer &gt;/dev/null &amp;&amp; export PATH="$HOME/.composer/vendor/bin:$PATH"


It should come first before your other drush. See my full .bashrc for details (bash4 syntax).



Alternatively install drush by specifying COMPOSER_BIN_DIR, like:

COMPOSER_BIN_DIR=/usr/local/bin composer global require drush/drush:dev-master


Assuming that /usr/local/bin is already in your PATH.