#in ubuntu/debian, try one of
sudo apt-get install php-dev
sudo apt-get install php5-dev
sudo apt-get install php7-dev
sudo apt-get install php7.0-dev
sudo apt-get install php7.1-dev
sudo apt-get install php7.2-dev

#in redhat/centos/fedora, try one of
yum install php-devel

#then build the extension
phpize
./configure
make
sudo make install

#this should install diseval.so in a place like: /usr/lib/php/20160303/
#to enable it, go to php.ini and add
extension=diseval.so

#or go to something like
/etc/php/mods-available/

#create a file, diseval.ini
extension=diseval.so

#and then in one of
#/etc/php/cli/conf.d
#/etc/php/fpm/conf.d
#/etc/php/apache2/conf.d
ln -s ../../mods-available/diseval.ini




