Modify php.ini:

Remove the one before openssl;

Download the poser.phar file to your working directory. This file is the Composer execution file, which is a PHAR(PHP archive file, which can contain any file and can be executed at the PHP command line).

Second, install Composer to the specified directory, that is, add the -install-dir option parameter after the command line. Use the following command:

$ curl -s (Composer website)/installer | PHP-install-dir = bin