install GRPC (MAMP)

1. download PECL:
$ curl -O https://pear.php.net/go-pear.phar 

2.install PECL in MAMP PHP folder:
$ sudo php -d detect_unicode=0 go-pear.phar

!!! make sure the installation directories look like this: !!!

 1. Installation base ($prefix)                   : /Applications/MAMP/bin/php/php7.2.14
 2. Temporary directory for processing            : /tmp/pear/install
 3. Temporary directory for downloads             : /tmp/pear/install
 4. Binaries directory                            : /Applications/MAMP/bin/php/php7.2.14/bin
 5. PHP code directory ($php_dir)                 : /Applications/MAMP/bin/php/php7.2.14/share/pear
 6. Documentation directory                       : /Applications/MAMP/bin/php/php7.2.14/docs
 7. Data directory                                : /Applications/MAMP/bin/php/php7.2.14/data
 8. User-modifiable configuration files directory : /Applications/MAMP/bin/php/php7.2.14/cfg
 9. Public Web Files directory                    : /Applications/MAMP/bin/php/php7.2.14/www
10. System manual pages directory                 : /Applications/MAMP/bin/php/php7.2.14/man
11. Tests directory                               : /Applications/MAMP/bin/php/php7.2.14/tests
12. Name of configuration file                    : /Applications/MAMP/Library/etc/php/7.2.14/pear.conf


3/ Install GRPC
(seems to work ->) $ sudo pecl install grpc
(seems more logical ->) $ sudo /Applications/MAMP/bin/php/php7.2.14/bin/pecl install grpc