First update the server :

yum -y update

Switch into the /usr/local/src directory.

cd /usr/local/src

Install Composer by using cURL

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

To use Composer globally run this below command ensure to use as user and user should have full shell access in order to use it :

mv -f composer.phar /usr/local/bin/composer

to check composer version :

composer -V

to run composer via different php version use full path of php bin and composer path eg :

/usr/local/bin/php /usr/local/bin/composer command

All selectors php bin path can be found in /opt/alt

eg :

/opt/alt/php73/usr/bin/php /usr/local/bin/composer command