CLI vs web-server integration

As described in PHP-FPM you can have different configurations for different web pages.

One advantage for that is the fact, that you can have different PHP versions for different web pages.

But these configurations don’t change the system-wide installed PHP version.

This means, that the PHP version from a PHP-Info file doesn’t have the be the same coming from the web-server and coming from the CLI.

php -v
PHP 7.2.19-1+ubuntu18.04.1+deb.sury.org+1 (cli) (built: May 31 2019 11:17:15) ( NTS )
Copyright (c) 1997-2018 The PHP Group
Zend Engine v3.2.0, Copyright (c) 1998-2018 Zend Technologies
    with Zend OPcache v7.2.19-1+ubuntu18.04.1+deb.sury.org+1, Copyright (c) 1999-2018, by Zend Technologies
    with Xdebug v2.7.1, Copyright (c) 2002-2019, by Derick Rethans

How to change the system-wide default PHP version?

Note: This is only possible if you have root/sudo privileges on the server!

Via the following command you can find out where the php command is located:

which php

On my server this is:

/usr/bin/php

If you now check this “file” you see:

ls -al /usr/bin/php        
lrwxrwxrwx 1 root root 21 Jan  3  2018 /usr/bin/php -> /etc/alternatives/php

This means, that /usr/bin/php only points to /etc/alternatives/php. But as you can see on the path this is handled by the “alternatives”.

If you check this “file” you see:

ls -al /etc/alternatives/php        
lrwxrwxrwx 1 root root 15 May 31  2018 /etc/alternatives/php -> /usr/bin/php7.2

This now points to the “real” binary, which executes PHP.

ls -al /usr/bin/php7.2      
-rwxr-xr-x 1 root root 4899864 May 31 13:17 /usr/bin/php7.2

Therefore the command “php” points to “/usr/bin/php”, which points to “/etc/alternatives/php” and finally to “/usr/bin/php7.2”.

To change this “link” (and therefore change the CLI PHP version) you can execute the following command:

sudo update-alternatives --set php /usr/bin/php7.3

After that you successfully changed the PHP CLI from 7.2 to 7.3.

php -v
PHP 7.3.6-1+ubuntu18.04.1+deb.sury.org+1 (cli) (built: May 31 2019 11:06:48) ( NTS )
Copyright (c) 1997-2018 The PHP Group
Zend Engine v3.3.6, Copyright (c) 1998-2018 Zend Technologies
    with Zend OPcache v7.3.6-1+ubuntu18.04.1+deb.sury.org+1, Copyright (c) 1999-2018, by Zend Technologies
    with Xdebug v2.7.1, Copyright (c) 2002-2019, by Derick Rethans