composer upgrade self code example
Example 1: update composer mac
#Ubuntu-Download Composer and create a Phar (PHP Archive) file
$ curl -s https://getcomposer.org/installer | php
#Move it to bin directory
$ sudo mv composer.phar /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