If you find yourself in a similar situation, refer to the steps below. This brief tutorial shows students and new users how to list all compiled and installed PHP extensions on Ubuntu 16.04 | 18.04 and might also be workable on future Ubuntu versions. To list installed PHP extensions, follow the steps below:

List PHP Compiled Extensions

PHP / PHP-FPM has a list of all extensions that are compiled by default on Ubuntu. but not necessarily installed and in use. Extensions that are compiled with PHP installation are available to be used when necessary. With a normal PHP install, not every library is compiled and installed — so if some functions are not working, you should look at what PHP extensions are compiled and installed. So, to list compiled PHP / PHP-FPM extensions, run the commands below That should show you something similar to the list below:

List PHP Installed Extension

Now, to find out what PHP / PHP-FPM extensions are installed, you run the commands below: You should see a similar list below: That’s how you know which extensions are installed So if you only want to install PHP 7.3 extensions of what is currently installed with  PHP 7.2, simply use the commands above to list installed PHP extensions, then install those PHP 7.3 versions. That’s it! Congratulations! You have learned how to list PHP extensions to find out which are compiled and which are installed. You may also like the post below: