How To: Install PHP Composer on Mac OSX

.

1. Open a terminal and navigate to your user directory, ie cd /User/<USER_NAME>/
2. Run this command shown below to download Composer. This will create a Phar (PHP Archive) file called composer.phar:

   curl -sS https://getcomposer.org/installer | php
   

3. Now we move composer.phar file to a directory

   sudo mv composer.phar /usr/local/bin/

4. We want to run Composer with having to be root al the time, so we need to change the permissions:

   sudo chmod 755 /usr/local/bin/composer.phar
   

   
   
5. Next, we need to let Bash know where to execute Composer: 

   nano ~/.bash_profile
   

   Add this line below to bash_profile and save
    

   alias composer="php /usr/local/bin/composer.phar"
   

   Note: If you want to save the changes you've made in Nano Text Editor, press Ctrl + O . To exit Nano, type Ctrl + X . If you ask nano to exit from a modified file, it will ask you if you want to save it.
   
   and then run this command:
    

   source ~/.bash_profile

   
   
6. Finally, run: 

   composer --version
   

   
   

.
From: https://duvien.com/blog/installing-composer-mac-osx