how to update composer on centos 7 code example
Example: how to install composer centos 8
php -r "copy('https://getcomposer.org/installer', 'composer-setup.php');"
sudo php composer-setup.php --install-dir=/usr/local/bin --filename=composer
php -r "copy('https://getcomposer.org/installer', 'composer-setup.php');"
sudo php composer-setup.php --install-dir=/usr/local/bin --filename=composer