composer.phar use code example

Example 1: install composer mac

curl -sS https://getcomposer.org/installer | php
php composer.phar install
mv composer.phar /usr/local/bin/composer
open -e  ~/.zshrc
// or open -e  ~/.bash_profile
alias composer="php /usr/local/bin/composer"

Example 2: update composer

To update composer command just find location of composer.phar and update as:
 where composer 	#Retrieves you location of your composer.phar
 cd path_to_composer.phar #Move to directory with composer.phar
 php composer.phar self-update	#Update your composer